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1. 70 5 Econ Mmic Parametets onanio ed oet Pede reperi a ules aa a E A S 70 5 24 Economies OUEDULU isinsin a a a aa eg aua de Exin baa ges 74 APPENDIX A References iet nocent telae cet Meroe Eis RD NERA I soete isean 78 APPENDIX B Unit Conversi n Tables iioi errorae bn artt sa Chi aei s Um Pint ea ee UR RE ERU e s eU eEES 80 APPENDIX C California Compliance Requirements eere eerte nennen tenente 83 CHAPTER I Getting Started 1 1 Overview F Chart is a computer program useful for the analysis and design of active and passive solar heating systems The program is an implementation of methods developed at the University of Wisconsin Solar Energy Laboratory to estimate the long term average performance of Domestic Water Heating Systems Pebble Bed Storage Space and Domestic Water Heating Systems Water Storage Space and Domestic Water Heating Systems Active Collection with Building Storage Space Heating Systems Direct Gain Passive Systems Collector Storage Wall Passive Systems Pool Heating Systems General Solar Heating Systems e g process heating systems ntegral Collector Storage Domestic Water Heating Systems Weather data for hundreds of North American locations the 16 California climate zones and numerous other locations are included with the program The user can add new weather data The easiest way to become acquainted with F Chart is to try an example problem u
2. Chapter 2 2 5 2 The Edit Menu CT alo File Edit Preferences System Collector Data Run Plot Window Help Cut Ctrl x Copy Ctrl C Paste Ctrl V Monthly Ctrl M Copy Window Ctri A Cut Copy and Paste perform the normal Windows functions Monthly allows a parameter to assume monthly values To enter multiple values for a parameter select the parameter by clicking the mouse button on the parameter value If multiple values for this parameter are supported the Monthly menu item in the Edit menu will be active i e not dimmed Select the Monthly item from the Edit menu or use Ctrl M A dialog box will appear showing the default values of the parameter These values may be edited in the usual manner The dialog box has three buttons The Cancel button returns the program to the state it was in before the Monthly command was issued The Constant button causes the parameter to assume a single constant value equal to the first value displayed e g the January value Pressing Ok will result in the parameter being associated with the displayed values The word Monthly will be displayed in place of the parameter value To edit multiple values click on Monthly A maximum of seven monthly varying parameter values are allowed Copy Window places a copy of the active window on the clipboard The clipboard information may be pasted into other programs such as word processors spreadsheets or presentation software 2 5 3
3. Economic analysis detail Cost per unit area Area independent cost Price of electricity Annual increase in electricity Price of natural gas Annual increase in natural gas Price of fuel oil Annual increase in fuel oil Price of other fuel Annual increase in other fuel Period of economic analysis 70 Down payment Annual mortgage interest rate Term of mortgage Annual market discount rate Extra insur and maint in year 1 Annual increase in insur and m Eff Fed State income tax rate True property tax rate Annual increase in property tax Resale value Credit rate in tier 1 Maximum investment in tier 1 Credit rate in tier 2 Maximum investment in tier 2 Commercial system Commercial depreciation scheduli Economic analysis detail cycles through Brief Detailed and Cash Flow selection gives economic information about the first year the life cycle costs and the life cycle savings The Detailed option includes the information given under the Brief selection and in addition gives information on the breakdown of the life cycle economic costs The Cash Flow option includes all of the above and gives the annual cash position 71 Chapter 5 The Brief Cost per unit area is the cost per square foot or square meter of the solar collection system including such items as the storage costs that increase with increasing collector area If the total cost of the system is known then se
4. This parameter should not be changed without supplying modified values of the SRCC heat loss coefficient and the SRCC net energy delivery SRCC heat loss coefficient is the overall integral collector storage unit heat loss coefficient resulting from the nighttime cool down test as prescribed by SRCC Standard 200 SRCC net energy delivery is the periodic steady value of the daily useful energy collected by the integral collector storage system obtained from the ASHRAE 95 1981 test procedure under simulated environmental conditions as prescribed by SRCC Standard 200 Collector slope is the angle between the plane of the collector aperture and the horizontal This 66 Chapter 4 parameter may have monthly values The angle is measured in a vertical plane that is perpendicular to the line formed by the intersection of the plane of the collector aperture and the horizontal plane Collector azimuth South 0 is the angle between the projection into the horizontal plane of the normal to the collector aperture and the local meridian with the zero point directly facing the equator west positive and east negative The azimuth of a horizontal collector can have any value The azimuth of a collector facing the sun at noon in the southern hemisphere i e north facing is 180 This parameter may have monthly values Incidence angle modifier calculation cycles through Glazings Constant and Value s to indicate which of three possible methods
5. expressed as a percent of the initial 72 Chapter 5 investment Annual increase in insur and maint is the average expected inflation rate of these expenses previous parameter over the period of the economic analysis Eff Fed State income tax rate is the effective combined federal and state income tax rate of the solar system owner If tax laws do not permit deducting of state taxes on federal returns e g if the owner uses standard deductions on his her federal return then this parameter is the sum of the federal and state brackets in percent If state taxes are deducted from federal income for tax purposes then the effective rate is the sum of the federal and state rates minus their product True property tax rate is the ratio of the increment in real estate taxes due to the solar system to the cost of the solar system not the assessed tax value of the solar system expressed as a percent Some taxing districts specifically exempt solar systems in which case this parameter should be zero Annual increase in property tax is the anticipated average yearly rate of inflation of property taxes over the period of the economic analysis in percent This is often set equal to the general inflation rate Resale value is the anticipated resale or salvage value of the solar system at the end of the period of the economic analysis as a percent of the initial solar system cost If the solar system were added to a house and treated
6. Passive Direct Gain Passive Storage Wall Pool Heating General Heating System Integral Collector Storage Active Domestic Hot Water will open the parameter window for an active solar domestic hot water system The system consists of a solar collector optional freeze protection heat exchanger and either one or two storage tanks If a different system window is open at the time this command is issued it will be closed and removed from view with its parameters values retained If the active domestic hot water window is already open this command will cause the active domestic hot water system window to be moved in front of all other windows Pebble Bed Storage Space amp DHW will open the parameter window for a pebble bed system The pebble bed system is a space heating system using air or liquid solar collectors in which thermal energy is stored in heated pebbles A combined space and domestic hot water system can be analyzed If a different system window is open at the time this command is 16 Chapter 2 issued it will be closed and removed from view with its parameters values retained If the pebble bed window is already open this command will cause the pebble bed system window to be moved in front of all other windows Water Storage Space amp DHW will open the parameter window for a solar space and domestic water heating system in which thermal energy is stored in a water tank The system can be configured for just domestic
7. accept all of the changes Click cancel to disregard all changes 12 Chapter 2 2 4 Using Scroll Bars a 4 Many of the F Chart windows are equipped with vertical and horizontal scroll bars that allow the contents of a window that is larger than the screen to be viewed The operation of the scroll bars is as follows The indicator position represented by the small box can be controlled in three ways It can be moved either direction by clicking on the arrows Holding the mouse button down while it is positioned over the arrows causes a continuous slow scroll The indicator can be moved up and down in large discrete increments by clicking in the gray area above or below the indicator box By placing the cursor on the indicator box and holding the mouse button down the indicator can be dragged to any desired position 2 5 Menu Command Descriptions The remainder of this chapter provides detailed descriptions of each of the menu commands Menu names will be shown in bold Command names appearing in the menus will be shown in italics All of the information presented here is available in the on line Help menu 2 5 1 The File Menu O F chart lolx Fie Edit Preferences System Collector Data Run Plot Window Help Open Save C FCW MySystem FC Ctrl S Save as Print Ctrl P Printer Setup Exit Ctrl Q 1 CAFCWAMySystem FC Open will allow you to access and continue working on any file saved previously with the Sav
8. array area This flow rate may be different from the flow rate at which the collector was tested Typical values of this flow rate are 11 Ib hr ft or 0 015 kg s m for liquids and 9 Ib hr ft or 0 012 kg s n for air Collector fluid specific heat is the specific heat of the fluid flowing through the collectors 33 Chapter 3 Properties can be found in the ASHRAE handbook of Fundamentals 1985 or in any heat transfer textbook For water use 1 0 Btu Ib F or 4 19 kJ kg K For air use 1 0 kJ kg K or 0 24 Btu Ib F Modify Test Values Yes No toggles to indicate if the next two parameters should be used to account for differences in the collector parameters due to differences in the actual and test fluid flow rates and series parallel fluid flow circuit arrangements If this parameter is set to No the following three parameters are ignored Test collector flow rate area is the ratio of the collector fluid flow rate used in the collector test to the array area of the collector tested Usually a single collector panel is tested In this case this parameter is the ratio of the test collector fluid flow rate to the collector panel area This parameter is used only if Yes has been selected for modify test values Test fluid specific heat is the specific heat of the fluid used in the collector test Properties of common materials can be found in the ASHRAE Handbook of Fundamentals 1985 or in any heat transfer textbook This parameter is us
9. controlled by the first parameter in the economic parameter window The economics output resulting from the Brief setting is as follows Using the file DEFAULTS FC Economics Output Sel Fa Economics Summary First Year Fuel Cost 509 First Year Fuel Savings 715 Initial Investment 14520 Life Cycle Savings 3600 Life Cycle Costs Fuel 11284 Equipment 12258 Total 23542 74 Chapter 5 First year fuel cost is calculated by multiplying the cost per unit of auxiliary energy by the annual auxiliary requirements determined in the thermal analysis and dividing this result by the fuel usage efficiency First year fuel savings plus the first year fuel cost is equal to the non solar fuel cost Initial investment is calculated by multiplying the cost per unit area by the area and adding the fixed cost Life cycle savings are calculated by subtracting the present worth of the owning and operating costs from the present worth of the fuel savings both calculated for the period of the economic analysis This savings represents the economic advantage of the system over a fuel only system Life cycle costs is the sum of the present worth of the fuel cost and the owning and operating cost A breakdown of the life cycle costs is provided When the economics analysis detail is set to Detailed all of the above information will be presented along with a breakdown of equipment costs into expenses and credits Economics Output
10. flow rate to the collector panel area This parameter is used only if Yes has been selected for modify test values Test fluid specific heat is the specific heat of the fluid used in the collector test Properties of common materials can be found in the ASHRAE Handbook of Fundamentals 1985 or in any heat transfer textbook This parameter is used only if Yes is selected for modify test values 3 3 Compound Parabolic Concentrating Collector Compound Parabolic Concen LE X Number of collector panels Collector panel area FR UL Test slope FR TAU ALPHA Test intercept Concentration ratio Acceptance half angle Collector slope Collector azimuth South 0 degrees Receiver orientation m Incidence angle modifier Perpend Incidence angle modifier Parallel Collector flowrate area Ib hr ft 2 Collector fluid specific heat Btu lb F Modify test values Test collector flowrate area Test fluid specific heat Number of collector panels is multiplied by the area of a single collector panel to determine the total array area Collector panel area is either the gross or net aperture area of each collector panel The same gross or net aperture area that was used to determine FR TAU ALPHA and FR UL must 28 Chapter 3 be used for this parameter The ASHRAE Standard 93 77 1977 collector test recommends the use of gross area FR UL Test Slope is the product of the collector heat removal factor FR and the colle
11. for liquids and 9 Ib hr ft or 0 012 kg s m for air Collector fluid specific heat is the specific heat of the fluid flowing through the collectors Properties can be found in the ASHRAE handbook of Fundamentals 1985 or in any heat transfer textbook For water use 1 0 Btu Ib F or 4 19 kJ kg K For air use 1 0 kJ kg K or 0 24 Btu Ib F Modify Test Values Yes No toggles to indicate if the next two parameters should be used to account for differences in the collector parameters due to differences in the actual and test fluid flow rates and series parallel fluid flow circuit arrangements If this parameter is set to No the following three parameters are ignored Test collector flow rate area is the ratio of the collector fluid flow rate used in the collector test to the array area of the collector tested Usually a single collector panel is tested In this case this parameter is the ratio of the test collector fluid flow rate to the collector panel area This parameter is used only if Yes has been selected for modify test values Test fluid specific heat is the specific heat of the fluid used in the collector test Properties of common materials can be found in the ASHRAE Handbook of Fundamentals 1985 or in any heat transfer textbook This parameter is used only if Yes is selected for modify test values 32 Chapter 3 3 5 Two Axis Tracking Collector Two Axis Tracking Collector B XI Number of collector panels Collector p
12. for the pipe carrying fluid from the collector array This parameter is used only if Yes has been selected for pipe heat loss Collector store heat exch toggles between Yes and No to indicate if the following two parameters should be used to account for the performance penalty resulting from the heat exchanger between the collector array and the storage tank If No is specified the following two parameters are ignored Tank side flow rate area is the mass flow rate of water from the storage tank through the collector storage heat exchanger divided by the total array area Set this parameter to a value that is larger than collector flow rate area for an internal heat exchanger This parameter is used only if Yes is selected for the collector storage heat exchanger Heat exchanger effectiveness is the ratio of the actual to maximum possible heat transfer rates for heat exchanger located between the collector and the storage unit This parameter is used only if Yes is selected for the collector storage heat exchanger The output for the default values which represents a process heating system in English units is Thermal Output ol x Solar Load QTank Aux f 109 Btu 10 Btu 10 Btu 10 Btu Jan 17 98 15 50 0 622 12 95 0 165 Feb 20 06 14 00 0 572 10 62 0 242 Mar 23 99 15 50 0 639 11 09 0 285 Apr 24 94 15 00 0 627 9 81 0 346 May 27 89 15 50 0 658 9 22 0 405 Jun 28 46 15 00 0 646 8 04 0 464 Jul 29 52 15 50 0 675 7 70 0 503
13. gross or net aperture area that was used to determine FR TAU ALPHA and FR UL must be used for this parameter The ASHRAE Standard 93 77 1977 collector test recommends the use of gross area FR UL Test Slope is the product of the collector heat removal factor FR and the collector overall heat loss factor UL FR UL is the negative of the slope of the straight line efficiency plot obtained from the ASHRAE Standard 93 77 1977 collector test FR TAU ALPHA Test Intercept is the product of the collector heat removal factor FR and the transmittance absorptance product TAU ALPHA at normal incidence This parameter is also known as the optical efficiency It is the Y intercept of the straight line efficiency plot obtained from the ASHRAE Standard 93 77 1977 collector test Collector slope is the angle between the plane of the collector aperture and the horizontal This parameter may have monthly values The angle is measured in a vertical plane that is perpendicular to the line formed by the intersection of the plane of the collector aperture and the horizontal plane Collector azimuth South 0 is the angle between the projection into the horizontal plane of the normal to the collector aperture and the local meridian with the zero point directly facing the equator west positive and east negative The azimuth of a horizontal collector can have any value The azimuth of a collector facing the sun at noon in the southern hemisphere i e nor
14. heated Monthly values are allowed This parameter is used only if Yes has been selected for domestic hot 44 Chapter 4 water Environment temperature is the temperature of the surroundings of the domestic water storage tank to which heat losses occur Monthly values are allowed This parameter is used only if Yes has been selected for domestic hot water UA of auxiliary storage tank is the product of the energy loss coefficient and surface area for the auxiliary tank in the solar domestic water heating system In a single tank system use the tank surface area above the heating element thermostat This parameter is visible only if Yes has been selected for domestic hot water Pipe heat loss Yes No toggles to indicate if the following two parameters are to be used to calculate the effect of pipe heat losses If No is selected the following two parameters are ignored Inlet pipe UA is the overall loss coefficient pipe area product for the pipe carrying fluid to the collector This parameter is used only if Yes has been selected for pipe heat loss Outlet pipe UA is the overall loss coefficient pipe area product for the pipe carrying fluid from the collector array This parameter is used only if Yes has been selected for pipe heat loss Relative load heat exchanger size is the ratio of the actual thermal size of the load heat exchanger to the standard value The standard value is chosen such that the product of the load heat exchanger ef
15. is always normal to the solar position The collector may a flat plate or a concentrator using air or liquid 2 5 6 Data 15 x File Edit Preferences System Collector Data Run Plot Window Help Select Data Location Change View Data Add New Data Create New Data File Select Data Location is used to first select a file of weather data and then to select the city from the file When searching for a particular city select a city and then press the first letter in the name of the desired city There is a check box to the calculations for all cities in a file rather than one at a time When all cities is selected a dialog box appears asking for the name of a file where data will be sent Information in this file can be later manipulated Weather data for the 16 California climate zones have been supplied by the California Energy Commission The data for those cities that are in both the original F Chart database and the CEC database are not the same The F Chart database USA Old comes from a 1978 DOE report Input Data for Solar Systems by V Cinquemani J R Owenby Jr and R G Baldwin prepared under interagency agreement no E 49 26 1041 The F Chart database USA_New comes from the National Solar Radiation DataBase NSRDB created by the National Renewable Energy Laboratory NREL 19 Chapter 2 Change View data is used to examine or modify any of the meteorological data for the currently selected city indicated in the
16. lower right corner of the window and holding the mouse button down while dragging the mouse up or down to make the window longer or shorter Select Calculate from the Run Plot menu or enter F2 to initiate the calculations for this system in Madison Wisconsin When the calculations are completed two new windows will appear showing the performance and economics results The economics output window will be in front and by default it will display a summary of the economic calculations More detailed economic results including a year by year cash flow analysis can be obtained by changing the first parameter in the economics window Chapter 1 Economics Output PEST ER Economics Summary First Year Fuel Cost 509 First Year Fuel Savings 715 Initial Investment 14520 Life Cycle Savings 3600 Life Cycle Costs Fuel 11284 Equipment 12258 Total 23542 Move the cursor to an exposed portion of the Thermal Output window to bring it to the front b Thermal Output a x Solar Heat Dhw Aux f 10 Btu 10 Btu 10 Btu 10 Btu Jan 1798 1869 2384 1364 0353 Feb 2006 15 24 2 148 877 0 495 Mar 23 99 12 36 2 368 4 95 0 664 Apr 24 94 7 11 2 277 0 72 0 924 May 27 89 3 27 2 341 0 00 1 000 Jun 28 46 0 83 2 255 0 00 1 000 Jul 29 52 0 37 2 326 0 00 1 000 Aug 28 06 0 68 2 330 0 00 1 000 Sep 24 07 2 43 2 263 0 00 1 000 Oct 21 02 6 28 2 351 1 34 0 844 Nov 14 38 10 95 2 287 7 82 0 409 Dec 14 05 16 53 2 378 13 66 0 2
17. m s Area 1 ft 0 092903 m l mile 2 58999 km linch 0 000645 m 80 Volume 1 fe 28 31681 1 gal 3 78544 1 f 7 48 gal l yard 0 7645 m Mass 1 Ib 0 453492 kg 1 oz 28 3495 g Temperature Scales F Cx 1 8 32 C F 32 x 5 9 K C 273 R F 460 Energy 1 Btu 1 05506 kJ 1 Therm 105 506 MJ 1 cal 4 1868 J 1 kW hr 3 6MJ l langley 41 86 kJ m Energy Flux 1 Btu hr f 3 15469 W m l langley hr 11 6277 W m 1 cal cm min 697 4 W m 1 Btu hr f F 5 67826 W m C 1 Btu hr ft F 1 70307 W m C Appendix B Volumetric Rate 1 cfm 0 47195 l s l gal min 0 06309 l s 1 gal min f 0 67911 s m 1 cfm ft 0 1968 s m Mass Flow Rate 1 lb hr 0 000126 kg s 1 Ib hr ft 0 001356 kg s m Temperature Differences 1F 0 55556 C 1C 1 8 F Power 1 Btu hr 0 29307 W 1 ton refg 3 51685 kW 1 kcal hr 1 163 W 1 hp 0 74570 kW Appendix B NUMERICAL VALUES OF SOME PROPERTIES Solar Constant Density Air 1 204 0 07516 Water 1000 62 4 8 34 Rock 2400 150 Antifreeze 1065 50 Ethylene 66 5 glycol water 1353 W m 1 940 langleys min 428 Btu hr ft kg m lb ft kg m lb ft lb gal kg m lb ft kg m lb ft 82 Specific Heat 1012 J kg C 0 241 BTU Ib F 4190 J kg C 1 00 BTU Ib F 838 J kg C 0 2 BTU Ib F 3350 J kg C 0 80 BTU Ib F APPENDIX C California Compliance Requirements The sta
18. menu title A dialog box will appear showing monthly values of the solar radiation ambient temperature and ground reflectance Click the cancel button if you are just viewing the data Any of these values can be changed Click the OK button after making the desired changes These changes will be stored along with other specific system information when the Save or Save as command is used It is also possible to permanently store the data independent of the system description by clicking the Archive button The Archive process permanently alters the master data file so be sure that you have a backup copy Add New Data allows the user to enter meteorological data for a new location A dialog box will appear with rectangular boxes in which the city name latitude and monthly average values of the solar radiation ambient temperature and ground reflectance Click the Ok button to save the data The city name will not be placed on a map but will appear in the list of cities shown with the Cites Not on Map command This command will permanently alter the master data file It is not possible to delete a city Be sure that you have a backup copy of the original program Create new Data File allows the user to select data from individual cities in any of the city files and construct a new city file 2 5 7 Run Plot CT lolx File Edit Preferences System Collector Data Run Plot Window Help Calculate F2 Parametric Plot Monthly Plot Calcula
19. of Fundamentals 1985 or in any heat transfer textbook For water use 1 Btu Ibm F or 4190 J kg K Tank liquid density is the density of the liquid in the storage tank Properties of common materials can be found in the ASHRAE Handbook of Fundamentals 1985 or in any heat transfer textbook For water use 62 4 lbm ft or 1000 kg m UA of solar storage tank is the product of the energy loss coefficient and surface area for the solar storage tank Tank environment temperature is the temperature of the surroundings of the storage tank to which heat transfer losses occur Monthly values are permitted Fuel cycles through the four possibilities Electricity Gas Oil Other of the back up fuel where Other represents for example wood This parameter is used only in the economic evaluation Efficiency of fuel usage represents the average furnace efficiency of the back up conventional fuel This parameter is used in the economics calculations and it may vary monthly 63 Chapter 4 Pipe heat loss toggles between Yes and No to indicate if the following two parameters are to be used to calculate the effect of pipe heat losses If No is selected the following two parameters are ignored Inlet pipe UA is the overall loss coefficient pipe area product for the pipe carrying fluid to the collector array This parameter is used only if Yes has been selected for pipe heat loss Outlet pipe UA is the overall loss coefficient pipe area product
20. or independent calculations you may change the value of UA monthly so the program calculates the the known monthly load F Chart will multiply the UA and the degree days and either the number of hours in a day English units or seconds in a day SI units to determine the load Consequently the monthly value of UA must be calculated as Monthly Load in BTUs Degree days in F days 24 for English units or as Monthly Load in Joules Degree days in C days 24 3600 for SI units Building storage capacity is the effective energy storage capacity of the building A value of 6 BTU per square foot 123 KJ per square meter of floor area is recommended for residential construction This parameter may have monthly values Low thermostat set temperature is the temperature of the indoor space at which the auxiliary furnace turns on This parameter may have monthly values Daily internal generation is the monthly average daily energy generated within the building by appliances lights people and solar gains other than those attributed to the solar collector system This parameter may have monthly values Allowable temperature swing is the number of degrees above the low set point temperature which the indoor space may be heated to before the solar collector fluid flow is terminated This parameter may have monthly values Fuel cycles through the four possibilities of the back up fuel Electricity Gas Oil Other where Other represents for exam
21. outdoors when night insulation is not in place This is the reciprocal of the window overall resistance Monthly values are permitted Nighttime window conductance is the overall heat transfer coefficient per unit area between indoors through the glazing system to outdoors when night insulation is in place Insulation is assumed to be in place from sunset to sunrise This is the reciprocal of the window overall resistance Monthly values are permitted Building UA is the building overall energy loss coefficient area product NOT including the contribution of the passive element This parameter may have monthly values See Chapter 25 of the ASHRAE Handbook of Fundamentals 1985 for additional information Building storage capacity is the effective energy storage capacity of the building A value of 6 BTU per square foot 123 KJ per square meter of floor area is recommended for residential construction This parameter may have monthly values Low thermostat set temperature is the temperature of the indoor space at which the auxiliary furnace turns on This parameter may have monthly values Daily internal generation is the monthly average daily energy generated within the building by 52 Chapter 4 appliances lights people and solar gains other than those attributed to the solar collector system This parameter may have monthly values Allowable temperature swing is the number of degrees above the low set point temperature which the ind
22. parameters are ignored Inlet pipe UA is the overall loss coefficient pipe area product for the pipe carrying fluid to the collector array This parameter is used only if Yes has been selected for pipe heat loss Outlet pipe UA is the overall loss coefficient pipe area product for the pipe carrying fluid from the collector array This parameter is used only if Yes has been selected for pipe heat loss The output for the default values in English units is as follows Thermal Output nl x Q Coll Q Pool Load Aux f Pool T 10 Btu 10 Btu 10 Btu 109 Btu F May 1452 2554 3672 2220 0 395 80 0 Jun 1598 2731 23 16 7 18 0 690 80 0 Jul 1743 2766 19 42 200 0 897 80 0 Aug 1646 23 93 25 75 928 0 639 80 0 Sep 1301 1760 3879 2578 0 335 80 0 Year 77 40 12204 143 84 66 44 0 538 Q Coll is the monthly solar energy delivered by the solar collectors to the pool 60 Chapter 4 Q Pool is the monthly solar energy directly absorbed by the pool Load is the monthly energy loss from the pool by evaporation convection thermal radiation and ground conduction minus the absorbed solar radiation Qpool Aux is the monthly energy that must be supplied by the backup pool heater to maintain the pool temperature at the specified value f is the fraction of the pool heating demand which is supplied by the solar collector system Direct absorption of solar radiation for outdoor pools is considered as a reduction to the pool heat
23. system Optical efficiency is the effective product of the glazing transmittance and tank absorptance Energy Loss Coefficient is the effective energy loss coefficienct of the ICS system to the ambient expressed per unit glazing area 69 CHAPTER 5 Economics The economic calculations done in F Chart are first year costs life cycle life cycle savings and cash flow Life cycle costs and savings are computed from present costs of energy from fuel and its anticipated inflation rate market discount rate an assumed period of economic analysis owning costs and operating costs The life cycle costs of owning and operating the improvement includes such items as interest and principle payments on funds borrowed to pay for the improvement e g on the incremental mortgage income tax effects of incremental property taxes and interest payments tax credits resale value depreciation etc In this chapter we discuss the meaning of the economic output and discuss each of the economic parameters The life cycle cost method as applied to solar energy systems can be found in Duffie and Beckman 1991 5 1 Economic Parameters The economic parameter list contains 28 parameters Two additional economic parameters are contained in the system parameter list the fuel type and the efficiency of fuel usage These two parameters are explained in the appropriate places in Chapter 4 The economic parameter list and explanations of the parameters follow
24. tank surface area above the heating element thermostat Auxiliary environmental temperature is the temperature of the surroundings of the auxiliary water heater to which heat losses occur Monthly values are allowed First month of use cycles through the 12 months to indicate the month of the year in which the integral collector storage unit will be put into operation It is assumed operation begins on the first day of the month Last month of use cycles through the 12 months to indicate the last month of the year in which the integral collector storage unit will be operating It is assumed operation stops on the last day of the month The thermal performance is calculated on a monthly basis Shown below is the output for the default parameter set in English units 68 Chapter 4 Thermal Output ml xl Solar Load Loss Aux 10 Btu 10 Btu 10 Btu 109 Btu May 2 14 1 73 0 41 1 36 Jun 2 05 1 67 0 39 127 Jul 2 04 172 0 41 1 31 Aug 2 08 172 0 41 1 30 Sep 2 04 1 67 0 39 1 29 Year 10 34 851 2 01 6 54 Optical Efficiency 0 48 Energy Loss Coefficient 0 25 Solar is the monthly total solar radiation incident on the collector surface Load is the monthly domestic hot water energy demand Loss is the monthly energy loss from the auxiliary storage tank Aux is the monthly total auxiliary energy required to supply the domestic hot water demand f is the fraction of the hot water energy demand which is supplied by the ICS
25. the ratio of the actual heat transfer rate to the maximum possible heat transfer rate for the air to water domestic hot water heat exchanger This parameter is used only if Yes has been selected for domestic hot water Duct losses Yes No toggles to indicate whether the following four parameters are to be used to calculate the effect of duct heat losses and air leaks If No is specified the following four parameters are ignored Inlet duct UA is the overall loss coefficient duct area product for the duct carrying air to the collector array This parameter is used only if Yes has been selected for duct losses Outlet duct UA is the overall loss coefficient duct area product for the duct carrying air from the collector array This parameter is used only if Yes has been selected for duct losses Percent duct leak rate is the percent of the collector outlet duct flow rate which is leakage The collector is assumed to be under negative pressure i e all leaks are into the ducts rather than out This parameter is used only if Yes has been selected for duct losses Leak location In Out Both cycles through In Out and Both to indicate the location of the duct air leakage The total air leakage into the ducts as specified by the percent duct leak rate may be assumed to occur from the inlet duct the outlet duct or evenly from both the inlet and outlet ducts This parameter is used only if Yes has been selected for duct losses The thermal
26. water heating by setting the building UA to 0 If a different system window is open at the time this command is issued it will be closed and removed from view with its parameters values retained If the water storage window is already open this command will cause the water storage system window to be moved in front of all other windows Building Storage will open the parameter window for a solar space heating system that does not have its own thermal storage unit When sufficient solar energy is available energy is stored in the building structure by raising the indoor temperature above the low thermostat set temperature A combined space and domestic hot water system can be analyzed In this case the presence of a water storage preheat tank is assumed If a different system window is open at the time this command is issued it will be closed and removed from view with its parameters values retained If the building storage window is already open this command will cause the building storage system window to be moved in front of all other windows Passive Direct Gain will open the parameter window for a direct gain passive solar space heating system A direct gain system is essentially a window that allows solar energy to enter and be stored with the building structure by raising the indoor temperature above the low thermostat set temperature If a different system window is open at the time this command is issued it will be closed and removed f
27. 0 00 Jun 28 46 0 83 2 255 0 00 Jul 29 52 0 37 2 326 0 00 Aug 28 06 0 68 2 330 0 00 Sep 24 07 2 43 2 263 0 00 Oct 21 02 6 28 2 351 1 73 Nov 14 38 2 287 8 02 Dec 14 05 2 378 Year 27441 27 709 Solar is the monthly total solar radiation incident on the collector surface Heat is the monthly total space heating demand Dhw is the monthly total water heating demand Aux is the monthly total auxiliary energy required to supply the space and domestic water heating demands f is the fraction of the space and domestic water heating demands which is supplied by the solar energy system The remaining fraction must be met by an auxiliary source 4 4 Building Storage Systems Shown in Figure 4 3 is a schematic of a simple solar space heating system which does not have a primary storage component Solar energy is used to heat a fluid usually air but possibly a liquid which is circulated through the collectors The useful energy gain of the fluid is transferred either directly for air or via heat exchange for liquids to the building space If the solar contribution is less than the instantaneous load all of the energy entering the space at this time is useful in offsetting auxiliary energy use If the solar gain exceeds the instantaneous load the building temperature will rise providing a means of energy storage If the building 46 Chapter 4 temperature exceeds the maximum allowable value the collector pump is turned off since the so
28. 10 Btu 10 Btu Jan 2766 1869 2384 10 35 Feb 3086 15 24 2 148 5 36 Mar X 3691 1236 2 368 1 82 Apr 38 36 711 2277 0 18 May 42 91 327 234 0 00 Jun 4378 083 2255 0 00 Jul 45 41 0 37 2 326 0 00 Aug 43 16 0 68 2 330 0 00 Sep 37 03 2 43 2 263 0 00 Oct 32 34 6 28 2 351 0 34 Nov 22 13 A 2 287 Dec 21 62 2 378 Year 422 17 27 709 Notice the non intuitive results Although the array area was increased by 5496 from 26 to 40 Chapter 1 panels the fraction of the load supplied directly by the system increased only from 58 4 to 71 5 There is another way to examine the effect of a parameter such as array area on the system performance and economics The Parametric Plot command in the Run Plot menu produces a plot of the solar fraction and or the life cycle savings as a function of many of the parameters For example let s plot of solar fraction and life cycle savings as a function of number of collector panels We need to bring the collector parameters window to the front but there are so many windows on the screen it is difficult to see the collector parameters window An easy way to bring the window to the front is to select Collector Parameters from the Window menu Clicking on Number of collector panels in the collector window will cause the cursor to flash on this parameter Now select Parametric plot from the Run Plot menu A dialog box will appear in which you enter low and high values for the Number of collector panels and the n
29. 6 Jul 2739 1731 0744 0570 Aug 23874 1781 0 6670 0613 Sep 2782 1677 0643 0617 Oct 3000 1735 0616 0 645 Nov 2782 1685 0649 0 615 Dec 2756 1 746 0730 0 582 Year 34232 20470 7 960 0 611 Heat is the monthly total space heating demand Dhw is the monthly total water heating demand Aux is the monthly total auxiliary energy required to supply the space and domestic water heating demands f is the fraction of the space and domestic water heating demands which is supplied by the solar energy system The remaining fraction must be met by an auxiliary source 4 2 Pebble Bed Storage Space and Domestic Water Heating Systems A common configuration of a solar heating system using a pebble bed for thermal is shown in Figure 4 2 Other arrangements of fans and dampers can be devised to result in an equivalent flow circuit Air is heated in the flat plate solar collector and circulated to either the house or to the pebble bed Energy is stored in the pebble bed by heating the pebbles with the circulating hot air At night or in cloudy weather when the available solar energy is insufficient to meet the heating load directly air is warmed as it is circulated through the pebble bed and is then delivered to the house Auxiliary energy is supplied from the furnace when the energy stored in the pebble bed is depleted Energy required for domestic hot water is provided in some systems by heat exchange with the hot air leaving the collector The thermal perfo
30. 77 Year 274 41 94 73 27 709 50 90 0 584 The system or economics parameters can easily be changed to determine the effect of alternative designs For example let s determine the performance for an array of 40 collector panels Click on an exposed portion of the collector parameter window to bring it to the front You may first want to use the Stack command in the Edit menu to organize the windows on the screen so that all of the title bars are visible Now move the mouse to position the cursor just after the 6 in the edit box for the Number of collector panels and double click the mouse The line for which changes are being made will now be highlighted i e displayed in inverse Chapter 1 Flat Plate Collector 2 nmi x Number of collector panels Collector panel area FR UL Test slope FR TAU ALPHA Test intercept Collector slope Collector azimuth South 0 Incidence angle modifier calculatic Number of glass covers Inc angle modifier constant Inc angle modifier value s Collector flowrate area Collector fluid specific heat Modify test values Test collector flowrate area Test fluid specific heat Now enter 40 for the number of collector panels Number of collector panels Select the Calculate command to repeat the calculations Both the Thermal and Economic Output windows will be updated The Thermal Output window will now appear like this Thermal Output maxi Solar Heat Dhw Aux 10 Btu 10 Btu
31. Aug 28 06 15 50 0 674 7 76 0 500 Sep 24 07 15 00 0 635 9 02 0 399 Oct 21 02 15 50 0 640 10 98 0 292 Nov 14 38 15 00 0 598 12 96 0 136 Dec 14 05 15 50 0 614 13 88 0 104 Year 274 41 182 50 7 601 124 02 0 320 64 Chapter 4 Solar is the monthly total solar radiation incident on the collector surface Load is the monthly total thermal energy demand on the system at a temperature above the specified minimum useful temperature Q Tank is the monthly total energy loss from the storage tank Aux is the monthly total auxiliary energy which must be supplied in addition to the solar energy to meet the demand f is the fraction of the load supplied by the solar energy system The remaining fraction is supplied by an auxiliary source 4 9 Integral Collector Storage Water Heating Systems Integral collector storage ICS units are passive solar water preheaters that combine solar collection with thermal storage They are usually roof or ground mounted in series with a conventional domestic water heater and supplied by mains water An ICS unit is basically a black tank in an enclosure with an optical cover system as shown in Figure 4 8 There are many variations in design Some units have several tanks plumbed in series within the enclosure Others have internal reflector systems non flat covers or finned tanks ICS solar water heaters usually cost less than active systems and are inherently simple to install and maintain They often operate witho
32. F CHART User s Manual Windows Version F Chart Software Phone 608 836 8531 Fax 608 836 8536 www fchart com 1983 2001 by S A Klein and W A Beckman All rights reserved No part of this program or manual may be reproduced by any means or transmitted without the written permission of the authors The authors make no guarantee that the program is free from errors or that the results produced with it will be free of errors and they assume no responsibility or liability for the accuracy of the program or for the results which my come from its use Registration Number ALL CORRESPONDENCE MUST INCLUDE THE REGISTRATION NUMBER Printed in the USA F CHART User s Manual Windows Version F Chart Software Phone 608 836 8531 Fax 608 836 8536 www fchart com Table of Contents CHAPTER 1 Getting Started sesesestssscssadsccaisscsbeshpncessuvssdsoesyndesssseeccssobuadevouseechossveadsveussecssusedsayee 1 Tb HOST MWY MUR CE HE ERE 1 1 2 Cun RR 3 CHAPTER 2 Commands iret eint retos oacaas cH enira haue iai ess reae ERU sestu ssie seras sti5 binae E 12 2T Working with Menus 4 6o de a OUR dd dass ERN idis uet a a i 12 22 Changing Parameter Values esas nero see da ae e cade Aa evi eder d t D dpa 12 2 3 Dialog BOXES ue ie acte De Pt edm epo a eade etude 12 2 4 USME Seroll Bate ducto este da bone t crate inet ee ns a ee ee ab eese 13 2 5 Menu Command Descriptions ss s eere tenere ti td d rei ree tror rti eere ede Od Re eu
33. Preferences F Chart l MEA File Edit Preferences System Collector Data Run Plot Window Help SI Units Y English Units V Economics On Economics Off SI and English control the unit system in which parameter values are entered The currently 15 Chapter 2 selected unit system is indicated by a check mark in front of S7 Units or English Units in the menu The unit system can be changed at any point All system information including the weather data will be converted to the new unit system You can use F Chart to automatically do unit conversions by changing the unit system to that for which you know the parameter value entering the value and then changing back to the original unit system Economics On and Economics Off control the visibility of the economics parameter set By default the economics parameter window is visible To remove the economics window from view and to thereby bypass the economic calculations select Economics Off To make the economics window visible or to move it in front of all other windows select Economics On The economics parameters remain at their current values whether or not the economics window is visible However the economics calculations will be done only when the economics parameter window is visible 2 5 4 System o x File Edit Preferences System Collector Data Run Plot Window Help Active Domestic Hot Water V Pebble Bed Storage and DHW Water Storage and DHW Building Storage
34. The optimum slope for any month will be the latitude plus the average solar declination for that month Average monthly declinations are given in Table 1 6 1 of Duffie and Beckman 1991 To assign monthly values to the collector slope or to change the values place the cursor on the Collector slope parameter and select Monthly from the Edit menu or alternatively press Ctrl M and a dialog box will appear showing the monthly values which by default are all equal to 45 degrees Enter the following optimum values Chapter 1 Collector slope x Jan 4 degrees Feb 56 Mar j5 l ok Apr 4 Mid d P Constant Jun 0 8 8 Jul 2 Aug ERN X Cancel Sep fn Oct 3 Nov 62 Dec 66 Click the Ok button when the values are entered The dialog box will disappear and the system parameter window will be in front The edit box for Collector slope now contains the word Monthly to indicate that this parameter has monthly values You can change or view the values at any time by clicking the mouse button when the cursor is on the parameter Collector slope Monthly degrees Now pull down Calculate from the Run Plot menu or enter F2 to determine the increase in performance resulting from monthly orientation changes The contents of a window can be on the Clipboard using the Copy Window command in the Edit menu or enter Ctrl A Any of the output appearing on the screen can be printed Select Print fro
35. W A Solar Engineering of Thermal Processes 2 Ed Wiley Interscience New York N Y 1991 Erbs D G Klein S A and Beckman W A The Estimation of Degree Days and Ambient Temperature Bin Data from Monthly Average Temperatures ASHRAE Journal June 1983 Erbs D G Klein S A and Duffie J A Estimation of the Diffuse Radiation Fraction for Hourly Daily and Monthly Average Global Radiation SOLAR ENERGY Vol 28 pp 293 302 1982 78 Appendix B Evans B L and Klein S A A Design Method of Active Collection Passive Storage Space Heating Systems M S thesis Solar Energy Laboratory University of Wisconsin Madison Evans B L Klein S A and Duffie J A A Design Method for Active Passive Hybrid Space Heating Systems SOLAR ENERGY Vol 35 No 2 pp 189 197 1985 Klein S A Calculation of Flat Plate Collector Utilizability SOLAR ENERGY Vol 21 pp 393 402 1978 Klein S A and Beckman W A A General Design Method for Closed Loop Solar Energy Systems SOLAR ENERGY Vol 22 pp 269 282 1979 Monsen W A Klein S A and Beckman W A Prediction of Direct Gain Solar Heating System Performance SOLAR ENERGY Vol 27 pp 143 147 1981 Monsen W A Klein S A and Beckman W A The Un utilizability Method for Collector Storage Walls SOLAR ENERGY Vol 28 pp 421 430 1982 Sigworth H Wei J and Rosenfeld A H Reducing Swimming Pooling Heating Costs Comparisio
36. a Collector panel area is either the gross or net aperture area of each collector panel The same gross or net aperture area that was used to determine FR TAU ALPHA and FR UL must be used for this parameter The ASHRAE Standard 93 77 1977 collector test recommends the use of gross area FR UL Test Slope is the product of the collector heat removal factor FR and the collector overall heat loss factor UL FR UL is the negative of the slope of the straight line efficiency plot obtained from the ASHRAE Standard 93 77 1977 collector test FR TAU ALPHA Test Intercept is the product of the collector heat removal factor FR and the transmittance absorptance product TAU ALPHA at normal incidence This parameter is also known as the optical efficiency It is the Y intercept of the straight line efficiency plot obtained from the ASHRAE Standard 93 77 1977 collector test Collector slope is the angle between the plane of the collector aperture and the horizontal This parameter may have monthly values The angle is measured in a vertical plane that is 26 Chapter 3 perpendicular to the line formed by the intersection of the plane of the collector aperture and the horizontal plane Collector azimuth South 0 is the angle between the projection into the horizontal plane of the normal to the collector aperture and the local meridian with the zero point directly facing the equator west positive and east negative The azimuth of a horiz
37. als can be found in the ASHRAE Handbook of Fundamentals 1985 or in any heat transfer textbook Wall density is the density of the passive storage wall material Properties of common building materials can be found in the ASHRAE Handbook of Fundamentals 1985 or in any heat transfer textbook Wall specific heat is the specific heat of the passive storage wall material Properties of 55 Chapter 4 common building materials can be found in the ASHRAE Handbook of Fundamentals 1985 or in any heat transfer textbook Night insulation R value is the thermal resistance of night insulation applied between the passive storage wall and outdoors This parameter may have monthly values Building UA is the building overall energy loss coefficient area product NOT including the contribution of the passive element This parameter may have monthly values See Chapter 25 of the ASHRAE Handbook of Fundamentals 1985 for additional information Building storage capacity is the effective energy storage capacity of the building A value of 6 BTU per square foot 123 KJ per square meter of floor area is recommended for residential construction This parameter may have monthly values Low thermostat set temperature is the temperature of the indoor space at which the auxiliary furnace turns on This parameter may have monthly values Daily internal generation is the monthly average daily energy generated within the building by appliances lights people
38. ance Directory From CEC Appliance Directory See Table 2 Fixed input See Table 1 Single family 50 gal day Multi family 35 gal day See Table 1 See Table 3 B3 x 8 25 x 140 B2 x 365 1000 F for yr x DHW load for yr from F Chart output C1 C2 C3 A2 24 C4 x 1000 A3 x 365 x 8 25 x Al x B5 x 365 x 140 B4 1000 A4 x 3 414 x 3 1000 C4 C5 C6 Gas systems or C4 C5 x3 C6 for all electric systems TABLE 1 California Climate Zone CEC Zone City 1 Arcata 2 Santa Rosa 3 Oakland 4 Sunnyvale 5 Santa Maria 6 Long Beach 7 San Diego 8 El Toro AFB 9 San Fernando 10 Riverside 11 Red Bluff 12 Sacramento 13 Fresno 14 China Lake AFB 15 El Centro 16 Mount Shasta Lat 41 0 38 5 37 7 37 4 34 9 33 8 32 7 33 7 34 3 33 9 40 2 38 5 36 8 35 7 32 8 41 3 Appendix C Modeling Variables Temperatures Number of Environment Water Mains Freeze Days 52 1 60 5 57 9 65 16 56 9 65 1 60 3 65 8 60 3 65 24 63 5 70 1 62 9 70 1 73 0 70 1 63 6 70 1 63 3 70 14 62 8 65 22 60 3 65 17 62 3 65 28 55 9 65 124 72 6 70 22 42 8 60 130 If a solar system is being installed pump and control energy must be determined for the particular generic solar system type This energy can be determined from the fixed values listed below Other values are allowed if verification of pump and controller wattage is provided to the local building department 85 Appendix C TABLE 2 Determining Pumping Energy Sys
39. and solar gains other than those attributed to the solar collector system This parameter may have monthly values Allowable temperature swing is the number of degrees above the low set point temperature which the indoor space may be heated to before the solar collector fluid flow is terminated This parameter may have monthly values Fuel cycles through the four possibilities of the back up fuel Electricity Gas Oil Other where Other represents for example wood This parameter is used only in the economic evaluation of the system Efficiency of fuel usage represents the average furnace efficiency of the back up conventional fuel This parameter is used in the economics calculations and it may vary monthly The output for the default values in English unit is as follows 56 Chapter 4 Thermal Output ml x Solar Load Aux 105 Btu 10 Btu 10 Btu Jan 13 00 8072 4 216 Feb 1162 5884 2 635 Mar 1155 4667 1730 Apr 9 60 2 328 0 263 May 7 61 0 720 0 000 Jun 6 65 0 064 0 000 Jul 7 13 0 000 0 000 Aug 8 70 0 064 0 000 Sep 10 59 0 358 0 000 Oct 13 44 2 164 0 000 Nov 12 74 5 201 1 743 Dec 12 40 7 831 4 139 Year 12503 37 351 14 726 Solar is the monthly total solar radiation incident on the exterior glazing surface of the passive storage wall Load is the monthly total space heating demand Aux is the monthly total auxiliary energy required to maintain the indoor space above the low thermostat set point tempera
40. anel area FR UL Test slope FR TAU ALPHA Test intercept Concentration ratio Collector flowrate area Collector fluid specific heat Btu lb F Modify test values Test collector flowrate area Ib hr ft 2 Test fluid specific heat Btu lb F Number of collector panels is multiplied by the area of a single collector panel to determine the total array area Collector panel area is either the gross or net aperture area of each collector panel The same gross or net aperture area that was used to determine FR TAU ALPHA and FR UL must be used for this parameter The ASHRAE Standard 93 77 1977 collector test recommends the use of gross area FR UL Test Slope is the product of the collector heat removal factor FR and the collector overall heat loss factor UL FR UL is the negative of the slope of the straight line efficiency plot obtained from the ASHRAE Standard 93 77 1977 collector test FR TAU ALPHA Test Intercept is the product of the collector heat removal factor FR and the transmittance absorptance product TAU ALPHA at normal incidence This parameter is also known as the optical efficiency It is the Y intercept of the straight line efficiency plot obtained from the ASHRAE Standard 93 77 1977 collector test Concentration ratio is the ratio of the collector aperture area to the receiver area Collector flow rate area is the total mass flow rate of collector fluid through the collector array divided by the total collector
41. ase USA New comes from the National Solar Radiation DataBase NSRDB created by the National Renewable Energy Laboratory NREL The CEC calculation procedure for estimating the total water heating energy is reproduced here The tables needed to fill in the worksheet are also provided Table 1 lists the 16 climate zones the F Chart city number the storage tank environment temperature for Parameter 9 the water mains temperature and the number of freeze days per year The F Chart Chg View Data command in the Weather menu will have to be used to change the water mains temperatures to the values found in Table 1 Table 2 gives estimates of pump and controller annual energy use Table 3 gives the standby loss adjustment 83 Appendix C BW NO eR CALCULATION OF ANNUAL WATER HEATING ENERGY Equipment Data Tank capacity Recovery efficiency Hourly input rate Pumping energy Operating Data Tank set temp Water main temp Daily water load Environment temp Adj standby loss Water Heating Energy Annual recovery load Energy from non depletable resources Net annual recovery load Annual recovery energy Annual standby loss energy Pumping energy Total water heating energy 140 Gal Percent Btu hr Watt hr yr F F Gal day F Percent KBtu yr KBtu yr KBtu yr KBtu yr KBtu yr KBtu yr KBtu yr 84 From CEC Appliance Directory From CEC Appli
42. can be used for space heating There are other space heating applications for which TMIN may be higher or lower than 20 C as for example the solar heating of a warehouse which is to be maintained at 10 C In a water heating system TMIN will be the mains supply water temperature TMIN for industrial processes or air conditioning applications will depend on the particular installation Auxiliary energy is supplied if the solar energy is insufficient to meet the load 61 Chapter 4 Relief Valve Energy Supplied PP Load Figure 4 8 Closed Loop Solar Energy System The thermal performance of these general solar heating systems is calculated using the PHIBAR f Chart f chart method of Klein and Beckman 1979 which has been extended to open loop systems as described by Braun and Klein 1983 The thermal parameters and default values are listed below followed by descriptions of the parameters General Solar Heating System ml x Location Average daily energy use Average daily load flow Load heat exchanger effectivenes Minimum useful temperature Liquid storage tank volume Tank liquid specific heat Tank liquid density UA of solar storage tank Tank environment temperature Fuel Efficiency of fuel usage Pipe heat loss Inlet pipe UA Outlet pipe UA Collector store heat exch Btu hr F Btu hr F Tank side flowrate area Ib hr ft 2 Heat exchanger effectiveness Location is the location
43. conomic analysis detail to Cash Flow provides in addition to the outputs for the detailed setting the annual cash position for each year of the economic analysis which appears as follows Annual Cash Position Maint Prop Energy Tax NetPresent Year amp lns Tax CostSavingsSavings VWorth 0 0 0 0 5600 8920 8920 1 0 436 509 87 367 340 2 0 470 560 94 411 352 3 0 508 616 102 459 364 4 0 549 677 110 513 377 5 0 593 745 119 573 390 6 0 640 820 128 640 403 7 0 691 902 138 714 417 8 0 747 992 149 797 430 9 0 806 1091 161 888 444 10 0 871 1200 174 990 459 11 0 940 1320 188 1103 473 12 0 1016 1452 203 1228 488 13 0 1097 1597 219 1368 503 14 0 1185 1757 237 1522 518 15 0 1279 1933 256 1693 534 16 0 1382 2126 276 1883 550 17 0 1492 2339 298 2093 566 18 0 1612 2573 322 2326 582 19 0 1741 2830 348 2585 599 20 0 1880 3113 3 6 17391 3731 0 19934 29153 9587 30625 3600 76 Chapter 5 Maint amp Ins is the annual expense to maintain and insure the equipment Prop Tax is the annual property tax Energy Cost is the annual payment made for auxiliary fuel Tax Savings is the annual saving due to state and federal tax deductions For non commercial systems this term includes property taxes and interest For commercial systems maintenance insurance and fuel are tax deductible and these savings are included in this term In year 0 this column includes any additional state and federal rebates Net Savings is the differe
44. ctor overall heat loss factor UL FR UL is the negative of the slope of the straight line efficiency plot obtained from the ASHRAE Standard 93 77 1977 collector test FR TAU ALPHA Test Intercept is the product of the collector heat removal factor FR and the transmittance absorptance product TAU ALPHA at normal incidence This parameter also known as the optical efficiency is the Y intercept of the straight line efficiency plot obtained from the ASHRAE Standard 93 77 1977 collector test Concentration ratio is the ratio of the collector aperture area to the receiver area Acceptance half angle is the maximum angle measured from the axis of the CPC for which incident beam solar radiation will strike the absorber Collector slope is the angle between the plane of the collector aperture and the horizontal This parameter may have monthly values The angle is measured in a vertical plane that is perpendicular to the line formed by the intersection of the plane of the collector aperture and the horizontal plane Collector azimuth South 0 is the angle between the projection into the horizontal plane of the normal to the collector aperture and the local meridian with the zero point directly facing the equator west positive and east negative The azimuth of a horizontal collector can have any value The azimuth of a collector facing the sun at noon in the southern hemisphere i e north facing is 180 This parameter may have monthly valu
45. e or Save as commands After the confirmation for unsaved work a dialog box will appear showing the names of all previously saved F Chart files in the current folder Other folders can be accessed in the normal Windows manner Select a file by clicking the mouse button on the file name followed by a click on the Open button or alternatively by double clicking on the file name When an old file is opened the screen will return to the state it was in when the file was saved The nine most recently saved files are listed at the bottom and can be 13 Chapter 2 opened by double clicking on the desired file Save will store all of the information in your work session on the disk with the same file name and on the same disk drive with which it was last saved For a new work session you will be prompted to supply a file name just as if the Save as command were given All information concerning the work session is saved on the disk except the output The stored information includes any changes you may have made to the meteorological data and the load The Save menu item is deactivated 1 e dimmed after the save operation until a change is made Save as provides the same function as the Save command except that it will first prompt you to supply a file name This command allows you to save the work session with another name or in another folder than used previously A dialog box will appear in which you must supply a file name Enter the file name of y
46. e button down while the cursor is positioned over the arrows causes a continuous slow scroll The indicator can be moved up and down in large discrete amounts by clicking in the gray area above or below the indicator box By placing the cursor on the indicator box and holding the mouse button down the indicator can be dragged to any desired position Move the cursor to any exposed position on the Pebble Bed Storage system window and click the mouse button to bring this window to the front The default system parameters for the pebble bed system are Chapter 1 Location Pebble bed volume collector areg Building UA Fuel Efficiency of fuel usage Domestic hot water Daily hot water usage 80 gallons Water set temperature 140 0 F Environmental temperature 68 0 F UA of auxiliary storage tank Btu hr F Heat exchanger water flowrate 2000 0 Air water heat exch effectivene 0 50 Duct losses Inlet duct UA Outlet duct UA Percent duct leak rate Leak location Note that the rectangular boxes for the last four parameter values are filled in with shading and no values are displayed These four parameters are applicable only if Duct losses are considered in the calculation Clicking the mouse in the box for Duct losses toggles the display from No to Yes and will uncover the duct loss parameters To move the collector parameter window to the front place the cursor anywhere on the collector window and click the mouse button or issue t
47. e collector inlet temperature were equal to the ambient temperature FR UL accounts for thermal losses These parameters can be determined theoretically Duffie and Beckman 1991 or experimentally from the ASHRAE 93 77 collector test procedure 1977 Provision is made in the parameter set for each collector type to modify the test values of the collector parameters to account for incidence angle effects and changes in the collector fluid flow rate from the test value In the following sections of this chapter the parameter sets for each of the five solar collector types are displayed along with their default settings in English units A short description of each parameter is provided 3 1 Flat Plate Solar Collector Flat Plate Collector o x Number of collector panels Collector panel area 20 80 FR UL Test slope 0 740 FR TAU ALPHA Test intercept 0 700 Collector slope Collector azimuth South 0 degrees Incidence angle modifier calculatic Number of glass covers Inc angle modifier constant Inc angle modifier value s Collector flowrate area Ib hr ft 2 Collector fluid specific heat Btu lb F Modify test values Test collector flowrate area Ib hr ft 2 Test fluid specific heat Btu lb F 23 Chapter 3 Number of collector panels is multiplied by the area of a single collector panel to determine the total array area Collector panel area is either the gross or net aperture area of each collector panel The same
48. e the system is located Existing city data can be viewed or changed or data for a new city added from the Data pull down menu Window area is the area of the direct gain window Number of glazings cycles through 1 to 4 and is used to calculate the angular dependence of the transmittance of solar radiation 51 Chapter 4 Window slope is the angle between the plane of the glazing and the horizontal A vertical window will have a 90 slope Monthly values are permitted Window azimuth is the deviation of the normal to the direct gain window from south A due south orientation will have an azimuth of 0 degrees Due west and due east will have values of 90 and 90 respectively Monthly values are permitted In the southern hemisphere a direct gain window facing the sun at solar noon would have an azimuth angle of 180 Tau Alpha at normal incidence is the product of the glazing transmittance and room wall absorptance for solar radiation at normal incidence Monthly values are permitted The solar absorptance Alpha of the direct gain window and the room can be estimated from Alpha 1 p 1 p 1 T Areay Areap where p is the room wall solar reflectance t is the diffuse solar transmittance of the window Areaw is the window area Areag is the surface area of all walls floors and ceilings in the room Daytime window conductance is the overall heat transfer coefficient per unit area between indoors through the glazing system to
49. ed collector type If the same collector type is selected the command will cause the collector window to be moved in front of all other windows Flat Plate will open the parameter window for a flat plate solar collector The collector may be used with air or liquid Collector performance is described using ASHRAE 93 77 test results Evacuated Tube will open the parameter window for an evacuated tube collector Evacuated tubes are modeled in the same manner as flat plate collectors with the exception that incidence angle modifiers may be specified for the planes parallel and perpendicular to the 18 Chapter 2 tube axis The collector may be used with air or liquid Compound Parabolic will open the parameter window for a compound parabolic concentrating CPC solar collector The collector may be used with air or liquid CPC collectors are modeled in a manner similar to evacuated tubes except that beam radiation can be utilized only if it is within the collector acceptance angle 1 Axis Tracking will open the parameter window for a solar collector that can track the solar position by rotation about a single axis The axis may be horizontal as in east west and north south orientations or tilted as in a polar axis orientation The tracking collector may a flat plate or a concentrator 2 Axis Tracking will open the parameter window for a solar collector that can track the solar position by rotation about two axes so that the collector plane
50. ed only if Yes is selected for modify test values 34 CHAPTER 4 System and Output Descriptions The F Chart program can evaluate eight different solar energy system types Each system has its own input parameter set and output format A description of each system is provided in the following eight sections along with a description of its parameter set an example calculation and an explanation of the program output The economic parameters and output are the same for all systems and are described in Chapter 5 The algorithms used to calculate the thermal and economic performance of the systems can be found in the cited references following Chapter 5 The monthly average solar radiation on tilted surfaces is calculated for all systems from the horizontal solar radiation data by summing the long term average hourly values calculated using the isotropic sky model in the manner described in Section 2 15 of Duffie and Beckman 1991 The monthly diffuse fraction is estimated using the correlation developed by Erbs et al 1982 4 1 Active Domestic Hot Water System A common configuration of a solar domestic water heating system is the two tank system shown in Figure 4 1 The collector may heat either air or liquid The collected energy is transferred directly or via a heat exchanger to a domestic water preheat tank which supplies solar heated water to a conventional auxiliary water heater The water is further heated to the desired temperat
51. emperature Environmental temperature UA of auxiliary storage tank Pipe heat loss Inlet pipe UA Outlet pipe UA Relative load heat exchanger size Collector store heat exchanger Tank side flowrate area Heat exchanger effectiveness gallons ft 2 Btu hr F F 43 Chapter 4 Location is the location where the system is located Existing city data can be viewed or changed or data for a new city added from the Data pull down menu Water storage volume collector area is multiplied by the number of collector panels and the panel area to determine the volume of stored water used for thermal storage If the building UA is set to zero then calculations are done for solar domestic water heating only In this case this parameter should be the volume of the domestic water preheat tank divided by the total collector area In a single tank system use the volume below the heating element thermostat Building UA is the building overall energy loss coefficient area product See Chapter 25 of the ASHRAE Handbook of Fundamentals 1985 for additional information If only domestic hot water is to be considered this parameter should be set to zero This parameter may have monthly values If the monthly loads are known either from measurements or independent calculations you may change the value of UA monthly so the program calculates the the known monthly load F Chart will multiply the UA and the degree days and either the number of hour
52. ence angle modifier is independent of solar incidence angle The ten values as shown above for the default parameter set correspond to the incidence angle modifier values between 0 and 90 degrees in 10 degree increments Collector flow rate area is the total mass flow rate of collector fluid through the collector array divided by the total collector array area This flow rate may be different from the flow rate at which the collector was tested Typical values of this flow rate are 11 Ib hr ft or 0 015 kg s m for liquids and 9 Ib hr ft or 0 012 kg s m for air Collector fluid specific heat is the specific heat of the fluid flowing through the collectors Properties can be found in the ASHRAE handbook of Fundamentals 1985 or in any heat transfer textbook For water use 1 0 Btu Ib F or 4 19 kJ kg K For air use 1 0 kJ kg K or 0 24 Btu Ib F Modify Test Values Yes No toggles to indicate if the next two parameters should be used to 27 Chapter 3 account for differences in the collector parameters due to differences in the actual and test fluid flow rates and series parallel fluid flow circuit arrangements If this parameter is set to No the following three parameters are ignored Test collector flow rate area is the ratio of the collector fluid flow rate used in the collector test to the array area of the collector tested Usually a single collector panel is tested In this case this parameter is the ratio of the test collector fluid
53. equivalents That is they can be executed either by using the mouse or by pressing the Ctrl key followed by the appropriate letter or number as shown to the right of the command in the pull down menus 2 2 Changing Parameter Values The information needed to describe a system is contained in the system collector and economic parameter windows To change the values of these parameters move the cursor to the rectangular box containing the value and left click the mouse button The cursor will flash in the box to indicate that it is the active parameter Use the backspace key or drag the cursor to erase characters to the left of the flashing cursor Characters entered from the keyboard are placed to the right of the indicator A double click within the edit box will cause all of the characters in the edit box to be highlighted 1 e displayed in inverse video Pressing any key will replace the highlighted field with the character being typed All parameter values are checked after they are entered F Chart will immediately inform you of an improper parameter with an appropriate error message 2 3 Dialog Boxes Many of the menu commands such as Change View Load will produce a dialog box in which you must supply information Information which you can change is enclosed within a small rectangular edit box Default values if available will be displayed Values can be changed in the same manner as described for parameter values Click the Ok button to
54. es Receiver orientation EW NS toggles to indicate the axis orientation of the evacuated tubes Specify NS if the collectors are mounted vertically with the tube pointing up and down Incidence angle modifier Perpendicular values s are the incidence angle modifiers for the plane perpendicular to the tube axis i e the transverse plane The incidence angle modifier is the ratio of the transmittance absorptance product at an off normal incidence angle in the transverse plane to the normal incidence transmittance absorptance product This parameter may have either one or ten values A single value indicates that the incidence angle modifier is independent of solar incidence angle The ten values as shown above for the default parameter set correspond to the incidence angle modifier values between 0 and 90 degrees in 10 degree increments Incidence angle modifier Parallel value s are the incidence angle modifiers for the plane 29 Chapter 3 parallel to the tube axis i e the longitudinal plane The incidence angle modifier is the ratio of the transmittance absorptance product at an off normal incidence angle in the longitudinal plane to the normal incidence transmittance absorptance product This parameter may have either one or ten values A single value indicates that the incidence angle modifier is independent of solar incidence angle The ten values as shown above for the default parameter set correspond to the incidence angle
55. fectiveness and minimum capacitance rate i e mass flow rate times specific heat is equal to twice the value of the building UA This parameter may have monthly values Collector store heat exchanger Yes No toggles to indicate if the following two parameters should be used to account for the performance penalty resulting from the heat exchanger between the collector array and the storage tank If No is specified the following two parameters are ignored Tank side flow rate area is the mass flow rate of water from the storage tank through the collector storage heat exchanger divided by the total array area Set this parameter to a value which is larger than collector flow rate area in the collector parameter set for an internal heat exchanger Heat exchanger effectiveness is the ratio of the actual to maximum possible heat transfer rates for heat exchanger located between the collector and the storage unit This parameter is used only if Yes is selected for the collector storage heat exchanger 45 Chapter 4 The thermal performance is calculated on a monthly basis Shown below is the output for the default parameter set in English units with 26 flat plate solar collectors and collector fluid specific heat equal to 0 8 Thermal Output lol x Solar Heat Dhw Aux 10 Btu 10 Btu 10 Btu 10 Btu Jan 1798 1869 2384 13 90 Feb 2006 1524 2 148 9 18 Mar 2399 1236 2368 551 Apr 24 94 7 11 2 277 1 23 May 27 89 3 27 2 341
56. fied the following 6 parameters are ignored The liquid storage system should be selected if air collectors and a water to air heat exchanger are used to supply only domestic hot water Daily hot water usage is the average amount of hot water per day required at the set temperature Monthly values are allowed This parameter is visible only if Yes has been selected for domestic hot water parameter Water set temperature is the temperature to which domestic water is to be heated Monthly values are allowed This parameter is used only if Yes has been selected for domestic hot water Environment temperature is the temperature of the surroundings of the domestic water storage tank to which heat losses occur Monthly values are allowed This parameter is used only if Yes has been selected for domestic hot water UA of auxiliary storage tank is the product of the energy loss coefficient and surface area for the auxiliary tank in the solar domestic water heating system In a single tank system use the tank surface area above the heating element thermostat This parameter is visible only if Yes has been selected for domestic hot water Heat exchanger water flow rate is the mass flow rate of water from the solar preheat tank to the air water heat exchanger used only if Yes has been selected for domestic hot water Air water heat exch effectiveness is the ratio of the actual heat transfer rate to the maximum possible heat transfer rate for the air to
57. he Collector Parameters command from the Window menu The default flat plate collector parameter window will appear as Chapter 1 5 Flat Plate Collector n x Number of collector panels Collector panel area f ft 2 FR UL Test slope i Btu hr ft 2 F FR TAU AL PHA Test intercept Collector slope degrees Collector azimuth South 0 degrees Incidence angle modifier calculatic Number of glass covers Inc angle modifier constant Inc angle modifier value s Collector flowrate area Ib hr ft 2 Collector fluid specific heat Btu lb F Modify test values Test collector flowrate area 00C Ib hr ft 2 Test fluid specific heat Btu lb F There are several other window controls that you should be aware of The title bar at the top of the window displays a title indicating the window s contents When the window is active i e the front window the title bar will be displayed in color The title bar serves as a handle should you wish to move the window Move the cursor to a position within the title bar and press and hold the mouse button while dragging the window to a new position At the right corner of the title bar is a small box with an X referred to as the go away box Clicking the mouse button while the cursor is positioned in the go away box will cause the window to be removed from view The other two small boxes will minimize or maximize the window The vertical size of any of the windows can be changed by moving the cursor to the
58. he economic analysis It is assumed that the average rate occurs each year of the analysis Price of other fuel such as wood is the average purchase price per million BTU or per gigajoule paid in the first year Annual increase in other fuel is the anticipated average yearly inflation rate of heating fuel such as wood during the period of the economic analysis It is assumed that the average rate occurs each year of the analysis Period of economic analysis is the number of years over which the life cycle cost analysis is done Often this is 20 years or the same as the term of the mortgage Percent down payment is the percentage of the incremental cost of the solar system which 1s paid out at the time of installation The balance is paid for by a mortgage Annual mortgage interest rate is the yearly rate charged by the lender on funds borrowed in percent Term of the mortgage is the number of years over which the funds borrowed must be repaid Annual market discount rate is the yearly rate of return from the solar system owner s best alternative investment in percent For a home owner this is often the interest rate available at a bank either the savings account rate or the rate for certificates of deposit CD s For a business the internal rate of return of the company is often used Extra insur and maint in year 1 is the first year s extra insurance maintenance and other non fuel operating expenses attributable to the system
59. ing in a passive storage wall system are represented in Figure 4 6 During the month solar energy is transmitted through the glazings and absorbed on the storage wall The absorbed energy causes the outer wall temperature to rise and energy is then transmitted to the indoor space by conduction through the wall and via a convection loop through the gap between the wall and the glazings As with the direct gain system not all of the energy which enters the space is useful in offsetting the auxiliary energy consumption some of the energy may actually have to be removed to keep the space from becoming uncomfortably warm The Un utilizability method of Monsen Klein and Beckman 1982 is used to evaluate the performance of passive storage wall systems S Vent Aux Figure 4 6 Passive Solar Wall System The thermal parameters for the passive storage wall system are listed below along with the default values The parameter descriptions follow this list Passive Storage Wall lol x Location ALBUQUERQUE NM Wall area w2 Number of glazings Wall slope degrees Wall azimuth degrees Tau Alpha at normal incidence Wall thickness 3 ft Wall thermal conductivity Btu hr ft F Wall density Ib ft 3 Wall specific heat Btu lb F Night insulation R value ft 2 hr F Btu xl 54 Chapter 4 Building UA Building storage capacity 12900 0 Low thermostat set temperature 68 0 Daily internal generation 37440 0 Allowable tempera
60. ing load Pool T is the monthly average temperature of the pool If the heater capacity is sufficiently large then the pool temperature will be equal to the second parameter the Pool temperature If the heater capacity is not sufficient to maintain the pool temperature at the desired setting then the pool will reach an equilibrium temperature which balances the input energy from the sun and solar system with the pool losses 4 8 General Solar Heating Systems The solar energy system shown in Figures 4 2 and 4 8 represent the general classes of closed and open loop solar energy systems which can be used for a variety of applications including space heating absorption air conditioning water heating and process heating Solar energy is collected and stored as sensible heat in a liquid storage tank The storage tank is assumed to be pressurized or filled with a liquid having a high boiling point so that energy dumping i e energy loss through the pressure relief valve does not occur When required the heated liquid is either pumped from storage through a heat exchanger to supply thermal energy to the load closed loop system or the fluid is removed from the tank and replaced with cold fluid open loop system The load is a demand for energy above a minimum useful temperature TMIN The value of TMIN depends on the application For residential space heating TMIN is the indoor temperature of the building which is about 20 C All energy above 20 C
61. is to be used to calculate the effect of incidence angle on FR TAU ALPHA One of the next three parameters will be available depending upon the selection the other two will be hidden If Glazings is selected the Fresnel equations are used with nominal glass properties and the number of glazings will have to be selected If Constant is selected the ASHRAE incident angle modifier constant will be required If Value s is selected either a single incidence angle modifier or the incident angle modifier value for every 10 degrees will be required Number of glazings cycles through 1 to 4 to indicate the number of glazings on the solar collector Values of the monthly average incidence angle modifier are calculated using the Fresnel equations with glass properties and the method described in Duffie and Beckman 1980 Inc angle modifier constant b is the parameter which provides the best fit in the equation K t 1 0 b 1 cos t 1 0 where K t is the ratio of the transmittance absorptance product at incidence angle t to the normal incidence transmittance absorptance product The constant b is determined experimentally as described in the ASHRAE Standard 93 77 collector test procedure 1977 This parameter is visible only if Constant was chosen for the incidence angle modifier type Inc angle modifier value s are the the value s of the collector incidence angle modifier K t as determined by the ASHRAE Standard 93 77 collector test p
62. keyboard equivalents that are indicated in the menus For example the Print Chapter 1 command in the File menu which prints all information for the work session can be issued by entering Ctrl P Menus or commands within a menu that are not presently accessible are dimmed Dimmed items cannot be selected 1 2 Example Each system is described using three sets of parameters the collector the system and the economics sets All three sets are shown at the start of the program The economics parameter set will be in front and it will appear as follows Economic analysis detail Cost per unit area Area independent cost Price of electricity Annual increase in electricity Price of natural gas Annual increase in natural gas Price of fuel oil Annual increase in fuel oil Price of other fuel Annual increase in other fuel Period of economic analysis Down payment Annual mortgage interest rate Depending on the screen size the entire economics window may or may not fit on the screen When the entire window cannot be displayed the window will be provided with a scroll bar along the right hand side as indicated above Use of the scroll bar is needed to view the entire window The operation of the scroll bars is the same as in any Windows application The indicator represented by the sliding box can be controlled in three ways It can be moved incrementally in either direction by clicking on the arrows Holding the mous
63. lar gain cannot be used or stored at this time The algorithm used to do the monthly performance calculations for this system is presented by Evans and Klein 1983 A domestic hot water heat exchanger can be installed in the line leading from the collector In this case the monthly DHW solar contribution is calculated by the f Chart method Beckman Klein and Duffie 1977 Heat Exchanger Figure 4 4 Active Collection with Building Storage System The parameters for this system are listed below along with their default values and explanations Location Building UA Building storage capacity Low thermostat set temperature Daily internal generation Allowable temperature swing Fuel Efficiency of Fuel Usage Duct losses Inlet duct UA Outlet duct UA Percent duct leak rate Leak location Domestic hot water Daily hot water usage Water set temperature F Environmental temperature 68 0 F UA of auxiliary storage tank Btu hr F Heat Exchanger Water Flowrat 2000 0 Ib hr Air Water Heat Exch Effectiven 0 50 47 Chapter 4 Location is the location where the system is located Existing city data can be viewed or changed or data for a new city added from the Data pull down menu Building UA is the building overall energy loss coefficient area product See Chapter 25 of the ASHRAE Handbook of Fundamentals 1985 for additional information This parameter may have monthly values If the monthly loads are known either from measurements
64. like any other part of the house the percent resale value would be equal to the ratio of the house selling price at the end of the economic analysis divided by the house purchase price If the solar system were worn out and needed replacement at the end of the economic period then the resale value would be negative and equal to the removal cost divided by the initial solar system cost These two limits probably bracket the actual situation If the period of the economic analysis is long say 20 years or more then the resale value will have only a small effect on the life cycle cost Credit Rate in tier 1 Maximum investment in tier 1 Credit Rate in tier 2 Maximum investment in tier 2 These four parameters are provided to enter tax credits or government subsidies that effectively reduce the purchase price of the solar system Since some solar systems may be subsidized by more than one government agency provision has been made to consider credits from two agencies with different limits of eligibility Consider a state government with a tax credit of 25 on the first 2000 of investment and a federal government with a 40 credit on the first 10000 of investment The credit on the first 2000 would be 65 and the credit on the next 73 Chapter 5 8000 would be 40 The percent credit rate in tier one is 65 The maximum investment in tier one is 2000 The percent credit in tier two is 40 The maximum investment in tier 2 is 10000 Com
65. lution as the heat transfer fluid in the collector loop Alternatively water may be circulated directly through the collectors and drained at night or during periods of excessive cloudiness Energy is stored in the form of sensible heat in the water tank A water to air load heat exchanger is used to transfer heat from the storage tank to the building A liquid to liquid heat exchanger is used to transfer energy from the main storage tank to the domestic water preheat tank which in turn supplies solar heated water to a conventional water heater A single tank arrangement in which auxiliary heat is supplied to the upper portion of the solar preheat tank can also be evaluated A conventional 42 Chapter 4 heating unit e g a furnace heat pump or wood burner is used to meet the space heating load when the energy in the storage tank is depleted The f Chart method Beckman Klein and Duffie 1977 is used to evaluate the monthly system performance Relief Storage TH im Pre Heat House Tank Water Supply Figure 4 3 Water Storage Space and Water Heating System The water storage system input parameters and their default values appear below in English units followed by the parameter descriptions Water Storage House Heating System MEE Location Water volume collector area Building UA 0 if only DHW Fuel Efficiency of fuel usage Domestic hot water Daily hot water usage Water set t
66. m the File menu or enter Ctrl P to bring up the Print dialog box 10 Chapter 1 iv System Parameters iv Collector Parameters iv Economics Parameters iv Thermal Output iv Economic Output v Mi a E 5 X Cancel If a check appears in the box the item following the checkbox will be printed A dimmed item cannot be printed because it does not exist To select or unselect an item move the cursor to the il appropriate check box and click the mouse button By default the output will go to the printer Click the Print button to initiate the printing process Following the traditional Windows operating practice different printers can be selected using the Printer Setup option in the File menu You have now seen how the program is structured how to select a system change parameters and do the calculations Try running another example Don t forget the help feature Help is available for most menus commands and parameters by highlighting the object and pressing F1 The manual often provides additional information 11 CHAPTER 2 Commands 2 1 Working with Menus Commands are distributed among nine pull down menus appearing at the top of the screen To select a command place the cursor on the desired menu title press the left mouse button and while holding the button down slide the cursor to the command you wish to execute then let up the mouse button Many of the menu items have command key
67. ment thermostat Fuel cycles through the four possibilities of the back up fuel Elecricity Gas Oil Other where Other represents for example wood This parameter is used only in the economic evaluation Efficiency of fuel usage represents the average furnace efficiency of the back up conventional fuel This parameter is used in the economics calculations and it may vary monthly Daily hot water usage is the average amount of hot water per day required at the set temperature Monthly values are allowed Water set temperature is the temperature to which domestic water is to be heated Monthly values are allowed Environment temperature is the temperature of the surroundings of the domestic water storage 36 Chapter 4 tank to which heat losses occur Monthly values are allowed UA of auxiliary storage tank is the product of the energy loss coefficient and surface area for the auxiliary tank in the solar domestic water heating system In a single tank system use the tank surface area above the heating element thermostat Pipe heat loss toggles between Yes and No to indicate if the following two parameters are to be used to calculate the effect of pipe heat losses If No is selected the following two parameters are ignored Inlet pipe UA is the overall loss coefficient pipe area product for the pipe carrying fluid to the collector This parameter is used only if Yes has been selected for pipe heat loss Outlet pipe UA is the
68. mercial system toggles between Yes and No to indicate if the solar system can be depreciated for tax purposes and if fuel is deductible as a business expense If this parameter is set to Yes then the depreciation schedule in the next parameter is used in calculating taxes and fuel is assumed to be deductible as a business expense For a business that makes a profit and pays taxes the government subsidizes fuel Consequently commercial solar energy systems are harder to justify on economic grounds than residential or other non profit solar systems If fuel is deductible but depreciation is not allowed set this parameter to Yes and set the depreciation schedule to zero If depreciation is allowed but fuel is specifically not allowed as a business expense set this parameter to Yes and artificially increase the fuel cost by the effective income tax bracket For solar systems on private homes this parameter should be set to No Commercial depreciation schedule is applicable only if the commercial system parameter is set to Yes In this case then you may enter 10 yearly depreciation values that effect the taxes paid For a three year depreciation schedule the U S Government allows 25 38 and 37 For a five year schedule the rates are 15 22 21 21 and 21 For a ten year schedule the rates are 8 14 12 10 10 10 9 9 9 and 9 5 2 Economics Output The level of detail displayed for the economic calculations is
69. mine the total volume occupied by the pebbles including voids Building UA is the building overall energy loss coefficient area product See Chapter 25 of the ASHRAE Handbook of Fundamentals 1985 for additional information This parameter may have monthly values If the monthly loads are known either from measurements or independent calculations you may change the value of UA monthly so the program calculates the known monthly load F Chart will multiply the UA and the degree days and either the number of hours in a day English units or seconds in a day SI units to determine the load Consequently the monthly value of UA must be calculated as Monthly Load in BTUs Degree days in F days 24 for English units or as Monthly Load in Joules Degree days in C days 24 3600 for SI units Fuel cycles through the four possibilities of the back up fuel Electricity Gas Oil Other where Other represents for example wood This parameter is used only in the economic evaluation of the system Efficiency of fuel usage represents the average furnace efficiency of the back up conventional fuel This parameter is used in the economics calculations and it may vary monthly Domestic hot water toggles between Yes and No to indicate whether a solar domestic water heating system is part of the heating system If Yes is selected a solar domestic hot water system is considered in addition to the space heating system The following 6 parameters are
70. ml x Economics Summary First Year Fuel Cost 509 First Year Fuel Savings 715 Initial Investment 14520 Life Cycle Savings 3600 Life Cycle Costs Fuel 11284 Equipment 12258 Total 23542 Breakdown of Equipment Costs Expenses Down Payment 14520 Mortgage 0 Maint amp Ins 0 Property Tax 6453 Credits Interest 0 Depreciation 0 Resale 3115 Tax Credits 5600 75 Chapter 5 The Down Payment is assumed to be made at the beginning of the first year and is therefore not discounted The Mortgage cost is the present worth of the sum of the annual mortgage payments Maintenance and insurance costs are the sum of the present worth of the inflating annual payments Property taxes are also calculated as the sum of the present worth of the inflating annual payments However property taxes are a net cost since income tax deductions have been included Interest represents the tax benefit resulting from including the mortgage interest as a deduction on federal and state income tax forms Depreciation is the present worth of the depreciation calculated according the Commercial depreciation schedule for income producing buildings Resale is the present worth of the product which is the Resale value times the initial investment For commercial property the resale value is reduced by tax considerations The Tax credits from federal and state governments are calculated if Consider Rebates is set to Yes Setting the e
71. modifier values between 0 and 90 degrees in 10 degree increments Collector flow rate area is the total mass flow rate of collector fluid through the collector array divided by the total collector array area This flow rate may be different from the flow rate at which the collector was tested Typical values of this flow rate are 11 Ib hr ft or 0 015 kg s m for liquids and 9 Ib hr ft or 0 012 kg s n for air Collector fluid specific heat is the specific heat of the fluid flowing through the collectors Properties can be found in the ASHRAE handbook of Fundamentals 1985 or in any heat transfer textbook For water use 1 0 Btu Ib F or 4 19 kJ kg K For air use 1 0 kJ kg K or 0 24 Btu Ib F Modify Test Values Yes No toggles to indicate if the next two parameters should be used to account for differences in the collector parameters due to differences in the actual and test fluid flow rates and series parallel fluid flow circuit arrangements If this parameter is set to No the following three parameters are ignored Test collector flow rate area is the ratio of the collector fluid flow rate used in the collector test to the array area of the collector tested Usually a single collector panel is tested In this case this parameter is the ratio of the test collector fluid flow rate to the collector panel area This parameter is used only if Yes has been selected for modify test values Test fluid specific heat is the specific heat of the fl
72. n of Pool Covers Solar Collectors and other Options Lawrence Berkley Laboratory LBL 9039 1979 SRCC Standard 200 82 Test Methods and Minimum Standards for Certifying Solar Water Heating Systems Solar Rating and Certification Corporation Washington DC revised April February 1985 Theunissen P H and Beckman W A Transmittance Characteristics of Optically Non Symmetric Solar Collectors Proceedings of the International Solar Energy Society Meeting in Perth Australia 1983 Zollner A A Performance Prediction Methodology for Integral Collection Storage Solar Domestic Hot Water Systems M S Thesis Dept of Mechanical Engineering University of Wisconsin Madison 1984 Zollner A Klein S A Beckman W A A Performance Prediction Methodology for Integral Collection Storage Solar Domestic Hot Water Systems ASME Journal of Solar Energy Engineering Vol 107 pp 265 272 1985 79 APPENDIX B UNIT CONVERSION TABLES Basic Units meter m kilogram kg second S Kelvin K Length 1ft 0 3048 m 1 mile 1 6093 m 1 inch 25 4 mm 1 yard 0 9144 m SI UNITS Derived units length liter l volume 10 m mass Newton N force kg m s time Joule J energy N m temperature Watt W power J s Hour hr time 3600 s Decimal Multiples of Units tera T 10 giga G 10 mega M 10 kilo k 10 micro m 10 nano n 10 pico p 10 UNIT CONVERSIONS Velocity 1 ft min 0 00508 m s mile hr 0 44704
73. nce between the annual expenses incurred without a solar system and the expenses incurred with a solar system In year 0 this term is the difference between the down payment and the tax rebates Present Worth is the present worth of the Net Savings column The total of the Present Worth column is equal to the life cycle savings 77 APPENDIX A References ASHRAE Handbook of Fundamentals American Society of Heating Refrigeration and Air Conditioning Engineers Inc New York 1985 ASHRAE Standard 93 77 American Society of Heating Refrigeration Air Conditioning Engineers Methods of Testing to Determine the Thermal Performance of Solar Collectors New York N Y 1977 ASHRAE Standard 95 1981 American Society of Heating Refrigeration Air Conditioning Engineers Methods of Testing to Determine the Thermal Performance of Solar Domestic Water Heating Systems ASHRAE New York N Y 1981 Beckman W A Klein S A and Duffie J A Solar Heating Design by the f Chart Method Wiley Interscience New York N Y 1977 Braun J E Klein S A and Pearson K A An Improved Design Method for Solar Water Heating Systems SOLAR ENERGY Vol 31 No 6 1983 Braun J E and Mitchell J C Solar Geometry for Fixed and Tracking Surfaces SOLAR ENERGY Vol 31 No 5 1983 Buckles W E and Klein S A Analysis of Solar Domestic Water Heaters SOLAR ENERGY Vol 25 pp 417 424 1980 Duffie J A and Beckman
74. nd changed Monthly Plot plots monthly values of the calculated thermal performance parameters such as solar fraction incident solar energy and others as well as weather data These plots can only be generated after the calculate command has been issued When the Monthly Plot command is issued a dialog box appears First select either the Calculated performance or Weather data radio button and then select the quantity to be plotted The minimum and maximum values of the selected quantity will be displayed in the display format currently selected 2 5 8 Window lo x File Edit Preferences System Collector Data Run Plot Window Help System Parameters Collector Parameters Economic Parameters Thermal Output Economic Output Plot Window Tile Cascade System Parameters or any of the other windows can be moved to the front by selecting it Tile and Cascade organizes the open windows on the screen The Tile command will place all windows side by side in two columns The Cascade command places the window currently being edited in front and all other windows are positioned so that only their title bars are showing These commands only affect the visual display 21 Chapter 2 2 5 9 Help xl File Edit Preferences System Collector Data Run Plot Window Help Help Index Using Help F Chart Manual About F Chart f Chart Web Site Help Index will activate the help processor that provides specific information on the u
75. ndow Help The File menu provides commands for loading and saving work files and printing information The Edit menu provides for the usual Windows Cut Copy and Paste commands as well as providing for the specification of multiple e g monthly values of highlighted parameters The Preferences menu commands allow specification of the unit system English or SI and the visibility of the economics parameter window The System menu contains the commands to select the type of solar system that is to be analyzed The Collector menu allows specification of the type of solar collector array The Data menu shows the locations for which weather data are available as well as commands to view change or add weather data The Run Plot menu contains commands to run a specific system or to run multiple calculations for a range of values of a specific parameter Plotting capabilities are also provided The Window menu brings selected windows to the front and determines how windows are arranged The Help menu provides on line help as well as access to the manual Help is available for most menus commands and parameters by highlighting the object and pressing F 1 To select a command place the cursor on the desired menu title press the mouse button and while holding the button down slide the cursor to the command you wish to execute then let up the mouse button Help is available for all commands in the Help menu Many of the menu commands have
76. ng space The absorbed solar energy supplies some of the load ie the energy required to maintain the building at the low thermostat set point temperature The load is the sum of the energy losses back out the direct gain window and the losses including infiltration occurring from the rest of the building However not all of the absorbed solar energy is useful in offsetting the load some of the solar energy may be absorbed when the building space is at the high thermostat set point temperature In this case the excess 50 Chapter 4 energy will have to be removed to keep the building space from becoming uncomfortably warm Alternatively shades could be drawn to block the solar energy from entering the space The thermal performance of direct gain passive systems is calculated using the Un utilizability method of Monsen Klein and Beckman 1981 S Vent Aux Figure 4 5 Passive Direct Gain System The thermal parameters for direct gain systems are listed below followed by their descriptions 2 Passive Direct Gain System Location Window area Number of glazings Window slope Window azimuth Tau Alpha at normal incidence Daytime window conductance Nighttime window conductance Building UA 300 00 Building storage capacity 12380 0 Low thermostat set temperature 68 0 Daily internal generation 37440 0 Allowable temperature swing 10 0 Fuel Efficiency of fuel usage 70 00 Location is the location wher
77. of pool cover if any The fraction of the solar energy incident on the pool surface that is absorbed by the pool water when no cover is used is assumed to be 0 855 A film cover eliminates all evaporation losses when in place and has 0 837 of the incident solar radiation absorbed by the pool A bubble type pool cover eliminates evaporation and reduces convective losses The fraction of the incident solar radiation absorbed by the pool when the bubble type cover is in place is assumed to be 0 783 The R value for the bubble type cover is assumed to be 1 87 hr ft2 F Btu 0 33 m2 C W Hours per day covered is the average number of hours per day that the pool cover is in place This parameter can vary monthly Average pool depth is multiplied by the pool area to determine the pool volume Location Indoor Outdoor toggles to specify the location of the pool If the pool is indoors then the humidity and temperature of the controlled indoor space must be specified The pool calculations do not include energy to condition the indoor space of time shaded Outdoor is the percentage of solar radiation incident on an unobstructed horizontal surface which is incident on the outdoor pool surface This parameter can be used to estimate the effects of nearby buildings or trees or it can be used to modify the assumed cover transmittance and pool absorptance This parameter can vary monthly Average wind speed Outdoor is the average wind speed at the ou
78. ontal collector can have any value The azimuth of a collector facing the sun at noon in the southern hemisphere i e north facing is 180 This parameter may have monthly values Receiver orientation EW NS toggles to indicate the axis orientation of the evacuated tubes Specify NS if the collectors are mounted vertically with the tube pointing up and down Incidence angle modifier Perpendicular values s are the incidence angle modifiers for the plane perpendicular to the tube axis i e the transverse plane The incidence angle modifier is the ratio of the transmittance absorptance product at an off normal incidence angle in the transverse plane to the normal incidence transmittance absorptance product This parameter may have either one or ten values A single value indicates that the incidence angle modifier is independent of solar incidence angle The ten values as shown above for the default parameter set correspond to the incidence angle modifier values between 0 and 90 degrees in 10 degree increments Incidence angle modifier Parallel value s are the incidence angle modifiers for the plane parallel to the tube axis 1 e the longitudinal plane The incidence angle modifier is the ratio of the transmittance absorptance product at an off normal incidence angle in the longitudinal plane to the normal incidence transmittance absorptance product This parameter may have either one or ten values A single value indicates that the incid
79. oor space may be heated to before the solar collector fluid flow is terminated This parameter may have monthly values Fuel cycles through the four possibilities of the back up fuel Electricity Gas Oil Other where Other represents for example wood This parameter is used only in the economic evaluation Efficiency of fuel usage represents the average furnace efficiency of the back up conventional fuel This parameter is used in the economics calculations and it may vary monthly An example of the output for the direct gain system follows Thermal Output E ici xl Solar Load Aux 10 Btu 10 Btu 10 Btu Jan 8015 1726 12 12 Feb 8081 14 06 9 06 Mar 8244 1138 6 60 Apr 7271 6 52 2 83 May 6 880 2 96 0 16 Jun 6 609 0 74 0 00 Jul 7 014 0 33 0 00 Aug 7 704 0 60 0 00 Sep 7 778 2 20 0 00 Oct 8 065 5 74 2 15 Nov 6 111 10 08 6 44 Dec 6 319 15 25 11 11 Year 88 091 87 14 50 47 Solar is the monthly total solar radiation incident on the exterior surface of the direct gain window Load is the monthly total space heating demand Aux is the monthly total auxiliary energy required to maintain the indoor space above the low thermostat set point temperature 53 Chapter 4 f is the fraction of the total load including losses out the direct gain window which is supplied by the direct gain system The remaining fraction must be met by an auxiliary source 4 6 Storage Wall Systems The monthly energy flows occurr
80. our choice in the box The file name may have spaces but should not contain a colon The extension FC will be added automatically Click the Save button when the name and drive are correct Each time F Chart is started a default file called DEFAULTS FC is brought up If you wish you can change this default file by setting up the parameters windows as you like and then saving it with the name DEFAULTS FC in the folder where FCHART EXE is located Print will allow printing of the contents of any window to a printer A dialog box will appear with a number of check boxes on the left If a box is checked then the item it represents will be printed To enter or remove a check mark move the cursor to the box and click the mouse button Dimmed items cannot be printed because they do not exist Click Ok to start the print process To send output to a disk file rather than a printer go to the Windows Start menu and select Settings and then Printers Choose to add a printer A dialog box will appear and choose local printer When asked for the printer port choose File and then use Generic Text only for the printer driver In order to print to a text file choose the Generic Text only printer in the Printer Setup command Printer Setup brings up a dialog where you may choose your printer This command need be given only once provided that the same printer is used throughout the work session Quit command provides a graceful way to exit the program
81. overall loss coefficient pipe area product for the pipe carrying fluid from the collector array This parameter is used only if Yes has been selected for pipe heat loss Collector store heat exchanger toggles between Yes and No to indicate if the following two parameters should be used to account for the performance penalty resulting from the heat exchanger between the collector array and the storage tank If No is specified the following two parameters are ignored Tank side flow rate area is the mass flow rate of water from the storage tank through the collector storage heat exchanger divided by the total array area Set this parameter to a value that is larger than collector flow rate area in the collector parameter set for an internal heat exchanger Heat exchanger effectiveness is the ratio of the actual to maximum possible heat transfer rates for heat exchanger located between the collector and the storage unit This parameter is used only if Yes is selected for the collector storage heat exchanger The thermal performance is calculated on a monthly basis Shown below is the output for the default parameter set in English units with three flat plate solar panels in Miami FL 37 Chapter 4 Thermal Output Oo x Solar Dhw Aux f 10 Btu 10 Btu 10 Btu Jan 2873 1 748 0 695 0 603 Feb 2767 41577 0568 0 640 Mar 3 221 1742 0575 0 670 Apr 3 105 1 683 0560 0 667 May 2 841 1735 0716 0587 Jun 2492 1677 0796 0 52
82. performance is calculated on a monthly basis The output in English units for the default parameter with a flat plate collector appears below 26 panels and cp 0 24 41 Chapter 4 Thermal Output E ial xJ Solar Heat Dhw Aux f 10 Btu 10 Btu 10 Btu 10 Btu Jan 1798 1869 2384 13 64 0 353 Feb 2006 1524 2 148 877 0 495 Mar 2399 1236 2 368 495 0 664 Apr 2494 711 2277 0 72 0 924 May 27 89 327 2341 0 00 1 000 Jun 2846 083 2 255 0 00 1 000 Jul 2952 037 2 326 0 00 1 000 Aug 28 06 068 X 2330 0 00 1 000 Sep 2407 243 2 263 0 00 1 000 Oct 2102 628 2 351 134 0 844 Nov 1438 1095 2 287 782 0 409 Dec 14 05 16 53 2 378 13 66 0 277 Year 27441 94 73 27 709 50 90 0 584 Solar is the monthly total solar radiation incident on the collector surface Heat is the monthly total space heating demand Dhw is the monthly total water heating demand Aux is the monthly total auxiliary energy required to supply the space and domestic water heating demands f is the fraction of the space and domestic water heating demands which is supplied by the solar energy system The remaining fraction must be met by an auxiliary source 4 3 Water Storage Space and or Domestic Water Heating Systems The water storage solar heating systems considered here can supply space heat domestic hot water or both A schematic diagram of a typical combined space and domestic water heating system is shown in Figure 4 3 This system uses an antifreeze so
83. ple wood This parameter is used only in the economic evaluation of the system Efficiency of fuel usage represents the average furnace efficiency of the back up conventional fuel This parameter is used in the economics calculations and it may vary monthly Duct losses Yes No toggles to indicate whether the following four parameters are to be used to calculate the effect of duct heat losses and air leaks If No is specified the following four parameters are ignored Inlet duct UA is the overall loss coefficient duct area product for the duct carrying air to the collector array This parameter is used only if Yes has been selected for duct losses 48 Chapter 4 Outlet duct UA is the overall loss coefficient duct area product for the duct carrying air from the collector array This parameter is used only if Yes has been selected for duct losses Percent duct leak rate is the percent of the collector outlet duct flow rate which is leakage The collector is assumed to be under negative pressure i e all leaks are into the ducts rather than out This parameter is used only if Yes has been selected for duct losses Domestic hot water Yes No toggles to indicate whether a solar domestic water heating system is part of the heating system If Yes is selected a solar domestic hot water system is considered in addition to the space heating system The following 6 parameters are then used to describe the domestic water system If No is speci
84. rences in the actual and test fluid flow rates and series parallel fluid flow circuit arrangements If this parameter is set to No the following two parameters are ignored Test collector flow rate area is the ratio of the collector fluid flow rate used in the collector test to the array area of the collector tested Usually a single collector panel is tested In this case this parameter is the ratio of the test collector fluid flow rate to the collector panel area This parameter is used only if Yes has been selected for modify test values Test fluid specific heat is the specific heat of the fluid used in the collector test Properties of common materials can be found in the ASHRAE Handbook of Fundamentals 1985 or in 25 Chapter 3 any heat transfer textbook This parameter is used if Yes is selected for modify test values 3 2 Evacuated Tube Collectors Evacuated Tubular Collector Number of collector panels Collector panel area FR UL Test slope FR TAU ALPHA Test intercept Collector slope Collector azimuth South 0 degrees Receiver orientation Incidence angle modifier Perpend Incidence angle modifier Parallel Collector flowrate area Ib hr ft 2 Collector fluid specific heat Btu lb F Modify test values No Test collector flowrate area 11 000 Ib hr ft 2 Test fluid specific heat Btu lb F Number of collector panels is multiplied by the area of a single collector panel to determine the total array are
85. rmal incidence This parameter also known as the optical efficiency is the Y intercept of the straight line efficiency plot obtained from the ASHRAE Standard 93 77 1977 collector test Concentration ratio is the ratio of the collector aperture area to the receiver area Axis slope is the angle between the axis and the projection of the axis into the horizontal plane This parameter may have monthly values Axis azimuth South 0 is the angle between the projection of the axis into the horizontal 31 Chapter 3 plane and the local meridian An east west axis orientation will have an axis azimuth of 90 Incidence angle modifier are the value s of the collector incidence angle modifier K t as determined by the ASHRAE Standard 93 77 collector test procedure 1977 If a single value is used for this parameter then the incidence angle modifier is taken to be that constant value independent of solar incidence angle Alternatively values of this parameter may be specified for incidence angles between 0 and 90 degrees in 10 degree increments The incidence angle value s are used only if Value s was chosen for the incidence angle modifier type Collector flow rate area is the total mass flow rate of collector fluid through the collector array divided by the total collector array area This flow rate may be different from the flow rate at which the collector was tested Typical values of this flow rate are 11 Ib hr ft or 0 015 kg s m
86. rmance of the pebble bed storage system is estimated using the f Chart method 38 Chapter 4 as described by Beckman Klein and Duffie 1977 and in Duffie and Beckman 1991 Note that the thermal performance of a domestic water heating system alone without space heating should be evaluated using the active domestic hot water system described above even if air heaters are used Warm air Auxili to house Mealy Heat Fan Damper Exchanger Damper to tap Pebble Bed Return air from house Figure 4 2 Pebble Bed Storage Space and Water Heating System The parameters for the pebble bed storage system are listed below along with their default values in English units A description of each parameter follows the parameter listing Pebble Bed Storage System ei ES Location WI Pebble bed volume collector arez Building UA Fuel Efficiency of fuel usage Domestic hot water Daily hot water usage Water set temperature Environmental temperature UA of auxiliary storage tank Heat exchanger water flowrate Air water heat exch effectivene Duct losses Inlet duct UA Outlet duct UA Percent duct leak rate Leak location 39 Chapter 4 Location is the location where the system is located Existing city data can be viewed or changed or data for a new city added from the Data pull down menu Volume of pebble bed collector area is multiplied by the number of collector panels and the panel area to deter
87. rnally wrapped with an insulating blanket of R 12 Where blankets of lesser value are used in meeting the combined internal and external insulation level of R 16 as specified in Section 2 5352 1 of the regulations the adjustment procedure provided in the Appendix to the regulations must be used This appendix is not included in this manual Multiply the standby loss percent from the Directory for the given water tank capacity by the factor given below TABLE 3 Standby Loss Adjustment Tank Capacity Gal GAS ELECTRIC 15 24 90 92 25 34 80 80 35 44 71 80 45 54 66 76 55 64 62 74 65 74 55 72 75 84 54 67 85 94 53 67 95 and up 50 59 87
88. rocedure 1977 If a single value is used for this parameter then the incidence angle modifier is taken to be that constant value independent of solar incidence angle Alternatively values of this parameter may be specified for incidence angles between 0 and 90 degrees in 10 degree increments The incidence angle value s are used only if Value s was chosen for the incidence angle modifier type Fuel cycles through the four possibilities Electricity Gas Oil Other of the back up fuel where Other represents for example wood This parameter is used only in the economic 67 Chapter 4 evaluation Efficiency of fuel usage represents the average furnace efficiency of the back up conventional fuel This parameter is used in the economics calculations and it may vary monthly Daily hot water usage is the average amount of hot water per day required at the set temperature Monthly values are allowed This parameter is visible only if Yes has been selected for domestic hot water parameter Water set temperature is the temperature to which domestic water is to be heated Monthly values are allowed This parameter is used only if Yes has been selected for domestic hot water ICS unit tank volume is the volume of the integral collector storage unit UA of auxiliary storage tank is the product of the energy loss coefficient and surface area for the auxiliary tank in the solar domestic water heating system In a single tank system use the
89. rom view with its parameters values retained If the direct gain window is already open this command will cause the direct gain system window to be moved in front of all other windows Passive Storage Wall will open the parameter window for a collector storage wall passive solar space heating system In this system a masonry wall is used to absorb and store incident solar radiation that is later released within the building If a different system window is open at the time this command is issued it will be closed and removed from view with its parameters values retained If the collector storage window 1s already open this command will cause the collector storage system window to be moved in front of all other windows Pool Heating will open the parameter window for a solar pool heating system Both indoor and outdoor pools can be analyzed If a different system window is open at the time this command is issued it will be closed and removed from view with its parameters values retained If the pool system window is already open this command will cause it to be moved in front of all other windows 17 Chapter 2 General Heating System will open the parameter window for a general solar energy system The general solar energy system can be either a closed or open loop solar energy designed to supply thermal energy above a specified temperature It can represent a space heating water heating absorption air conditioning or process heating
90. ros 13 CHAPTER 3 Collector Parameter Sets 0 ccccsesssssscessosccosseccsssnsescosceiseseconssccstonsensecoossedeerbacceos 23 3 1 Flat Plate Solar Collector es acu asco otia dest e Dumb etus dup Obs i elu Un 23 3 2 Evacuated Tube Collectors ette se crat e merde OTIO ESAE UR ee ing 26 3 3 Compound Parabolic Concentrating Collector sse 28 3 4 One Axis Tracking Collector oa i eta tt re dtc d bti ee duo dat Ge diudua etaha 31 3 5 J wo Axis Tracking Collector iss eer tustora edna nice ccs vti i C eil 33 CHAPTER 4 System and Output Descriptions cereus eres nette ee eren nete en nettes etna se tnun 35 4 1 Active Domestic Hot Water Systetni uii osito ree ERR eR Ud Yemebe laeso reos a EMI 35 4 2 Pebble Bed Storage Space and Domestic Water Heating Systems sssse 38 4 3 Water Storage Space and or Domestic Water Heating Systems ssssssuss 42 4 4 Building OLB CS Stelle uat esce dots bees ereptus odab vna Spade a aea inerat 46 4 5 Passive Direct Gain Systems ood annn iv dao tiated Aisle deba a de uen 50 4 6 Storage Wall SVStemis ries dotate e e eoisto telae rotae eequd ec TEESE E TEKEK Noni ca xus 54 4T Pol Heating SystetiS A datus a exi qupa tuse n uude utum dun peau hi clasts 57 4 8 General Solar Heating Systems ssc costes Ane ta steer e t terae dete edens dU sd es 61 4 9 Integral Collector Storage Water Heating Systems 65 CHAPTER 5 Economics c
91. s for the pool heating system are listed below along with default values The parameter descriptions follows Pool Heating System lol x Location Pool surface area Pool temperature F First month of season Last month of season Cover Hours per day covered hr day Average pool depth ft Pool Location of time shaded Average windspeed miles hr Pool room rel humidity Pool room temperature F Fuel Heater Capacity Btu hr Efficiency of fuel usage Pipe heat loss Inlet pipe UA Outlet pipe UA Location is the location where the system is located Existing city data can be viewed or changed or data for a new city added from the Data pull down menu 58 Chapter 4 Pool surface area is the surface area of the pool water Pool temperature is the monthly average desired pool temperature It is assumed that the auxiliary pool heating system has sufficient capacity to maintain the pool at this temperature This parameter can vary monthly First month of season can be cycled through all months of the year to select the month that pool usage and heating begins It is assumed that heating begins on the first day of the selected month Last Month of Season can be cycled through all months of the year to select the month that pool usage and heating ends It is assumed that pool heating ends on the last day of this month Cover cycles through None Film and Bubble indicating the type
92. s in a day English units or seconds in a day SI units to determine the load Consequently the monthly value of UA must be calculated as Monthly Load in BTUs Degree days in F days 24 for English units or as Monthly Load in Joules Degree days in C days 24 3600 for SI units Fuel cycles through the four possibilities Electricity Gas Oil Other of the back up fuel where Other represents for example wood This parameter is used only in the economic evaluation Efficiency of fuel usage represents the average furnace efficiency of the back up conventional fuel This parameter is used in the economics calculations and it may vary monthly Domestic hot water Yes No toggles to indicate whether a solar domestic water heating system is part of the heating system If Yes is selected a solar domestic hot water system is considered in addition to the space heating system The following 6 parameters are then used to describe the domestic water system If No is specified the following 6 parameters are ignored The liquid storage system should be selected if air collectors and a water to air heat exchanger are used to supply only domestic hot water Daily hot water usage is the average amount of hot water per day required at the set temperature Monthly values are allowed This parameter is visible only if Yes has been selected for domestic hot water parameter Water set temperature is the temperature to which domestic water is to be
93. se to F Chart Help for any parameter is available by selecting the parameter and then either selecting Help Index or by pressing the F1 key Help on commands is obtained by dragging the cursor to the command of interest and pressing F1 or by selecting the command after issuing the Help Index command Using Help provides instructions on how to move around in the help processor F Chart Manual starts Adobe Acrobat and displays an electronic version of this manual About F Chart displays the window that comes up when the F Chart program is started This window lists the program version number and the registered owner This information must be supplied when making inquiries about the program f Chart Web Site opens the default browser program and sets the URL to the f Chart web site The program developers can be contacted by e mail through the web site 22 CHAPTER 3 Collector Parameter Sets Five types of solar collectors may be evaluated by F Chart for use with any of the active solar systems The collector type is chosen from the collector menu The basic equation relating the useful energy gain of the collector to meteorological variables has the same form for all five collector types as shown in Duffie and Beckman 1991 In each case the performance of the collector is described in terms of FR TAU ALPHA Fr ta and FR UL FRU FR TAU ALPHA also call the optical efficiency is the efficiency the solar collector would have if th
94. sing the default parameters supplied with the program F Chart conforms to the Windows standard interface and can be run with a minimum of instructions After you have become familiar with the program you may wish to review the detailed program instruction set in Chapter 2 and the collector system and economic parameter set descriptions in Chapters 3 4 and 5 When you start F Chart click on the file FCHART EXE a header will appear showing the version number registration number and your company information To proceed click OK F Chart Solar Energy System Analysis 1993 2001 S A Klein and W A Beckman Version 6 17W 0001 For use only by Sunny Smiles Sun Power Sun City F Chart Software www fchart com eMail info fchart com Chapter 1 After clicking the mouse button the header will disappear and three windows containing the collector system and economic parameters of the default system will appear The default system is a pebble bed space and domestic water heating system with a flat plate collector It is possible to change the default system to your specifications as described with the Save as command in the next chapter Before changing any of the values let s look at the available commands Commands are distributed among nine pull down menus Detailed descriptions of each of the commands can be found in the next chapter A brief summary follows File Edit Preferences System Collector Data Run Plot Wi
95. system If a different system window is open at the time this command is issued it will be closed and removed from view with its parameters values retained If the general system window is already open this command will cause it to be moved in front of all other windows Integral Collector Storage will open the parameter window for an integral collector storage ICS domestic water heating system The ICS system combines the collector with the water storage unit The analysis method requires test data from the SRCC test method If a different system window is open at the time this command is issued it will be closed and removed from view with its parameters values retained If the ICS system window 1s already open this command will cause it to be moved in front of all other windows 2 5 5 Collector 15 x File Edit Preferences System Collector Data Run Plot Window Help v Flat Plate Evacuated Tube Compound Parabolic 1 Axis Tracking 2 Axis Tracking The Collector menu can be accessed only after a system type has been chosen The passive direct gain collector storage wall and ICS systems do not require a collector specification The currently selected collector type is indicated by a check mark in the Collector menu If a different collector window is open at the time when a Collector menu command is issued it will be closed and removed from view with its parameters values retained and replaced by a new window with the select
96. t this parameter to zero and place the total cost into the Area independent cost parameter For a passive system this unit area cost should be only the incremental cost of the wall above the conventional wall If this cost is less than a conventional wall then use a negative cost per unit area Area independent cost is the cost of fixed equipment such as pumps controllers piping part of the storage and other costs that are independent of collector area If the total cost of the system is known then set this parameter to the total cost and place a zero in the Cost per unit area parameter Price of electricity is the average purchase price per kilowatt hour paid in the first year Annual increase in electricity is the anticipated average yearly inflation rate of electricity Chapter 5 during the period of the economic analysis It is assumed that the average rate occurs each year of the analysis Price of natural gas is the average purchase price per 100 cubic feet approximately per therm or per cubic meter paid in the first year Annual increase in nat gas is the anticipated average yearly inflation rate of gas during the period of the economic analysis It is assumed that the average rate occurs each year of the analysis Price of fuel oil is the average purchase price per gallon or per liter paid in the first year Annual increase in fuel oil is the anticipated average yearly inflation rate of oil during the period of t
97. tdoor pool surface The wind speed at a local meteorological station is often significantly higher than the average wind speed at a pool surface Sigworth et al 1979 recommend that for a well protected pool the wind speed reported by the weather bureau be reduced by a factor of 10 Fora 59 Chapter 4 moderately protected pool they recommend a factor of 5 This parameter can vary monthly Pool room relative humidity is the average relative humidity of the conditioned space in which the indoor pool is located Energy calculations for the pool system do not include energy to maintain the pool room conditions This parameter can vary monthly Pool room temperature is the average temperature of the conditioned space in which the indoor pool is located Energy calculations for the pool system do not include energy to maintain the pool room conditions This parameter may have monthly values Fuel cycles through the four possibilities of the back up fuel Electricity Gas Oil Other where Other represents for example wood This parameter is used only in the economic evaluation of the system Efficiency of fuel usage represents the average furnace efficiency of the back up conventional fuel This parameter is used in the economics calculations and it may vary monthly Pipe heat loss Yes No toggles to indicate if the following two parameters are to be used to calculate the effect of pipe heat losses If No is selected the following two
98. te initiates the calculations for the system described by the parameter values in the system and economics windows A dialog box will appear showing the progress of the calculations The Run command generates a performance output window and if the economics parameter window is open an economics output window Click the mouse button on the window you wish to view to bring it to the front These output windows can be output to a printer a disk file using the Print command Parametric Plot produces a plot of solar fraction and or live cycle savings versus any of the parameters that can have continuous values Place the cursor on a parameter in the system collector or economics parameters If the Parametric Plot command is available for the selected parameter then executing this command will bring up a dialog window where the 20 Chapter 2 range of the parameter is selected along with the number of calculations to make within that range A spline interpolation is done between points if the box in front of Spline fit is checked The plot may be copied to the Clipboard using the Copy Window command in the Edit menu Double clicking on any plot provides a means to change the character of the plot Any of the plotting attributes can be changed but pleasing plots will be obtained with the plot default settings The number of divisions axis font size plotted range the presence or absence of grid lines and linear or logarithmic scales can be selected a
99. te of California has special requirements for showing compliance with Title 24 Part 2 Chapter 2 53 Section 2 5351 This appendix has been prepared from the appropriate documents for F Chart users in California When calculating solar domestic hot water performance the Water Storage Space amp DHW system should be selected from the System menu The Building UA must be set to zero to turn off the house heating option and the Domestic hot water option must be set to Yes Some of the F Chart parameters and weather data have to be set according to the California code The storage tank is initially assumed to be perfectly insulated so that UA of auxiliary tank must be set to zero A special calculation method is used to estimate standby losses and is included in the calculation procedure outlined below The Water set temperature must be set to 140 F The Daily hot water usage must be set to 50 gal day unit for single family dwellings or to 35 gal day unit for multi family dwellings Weather data for the 16 California climate zones have been added to the F Chart database using data supplied by the California Energy Commission The data for those cities that are in both the original F Chart database and the CEC database are not the same The F Chart database USA Old comes from a 1978 DOE report Input Data for Solar Systems by V Cinquemani J R Owenby Jr and R G Baldwin prepared under interagency agreement no E 49 26 1041 The F Chart datab
100. tem Type Pump and Control Energy Watt hr yr Open loop direct Recirculation Draindown Closed loop indirect Drainback Anti freeze Oil Refrigerant phase change Air 85W pump 6 hrs day See below 5W controller 24 hrs day 85W pump 6 hrs day 247 470 5W controller 24 hrs day 2W draindown valve 24 hrs day 85W pump 6 hrs day 470 850 70W pump 6 hrs day 15W controller 24 hrs day 85W pump 6 hrs day 229 950 5W controller 24 hrs day 185W pump 6 hrs day 722 700 85W pump 6 hrs day 15W controller 24 hrs day 85W pump 6 hrs day 229 950 5W controller 24 hrs day 75W pump 6 hrs day 208 050 5W controller 24 hrs day Pumping energy for recirculation solar systems is dependent upon the number of freeze days in each climate zone Use the value found from the following equation to determine the pumping energy for recirculation systems Pump energy watts x 12 x freeze days yr 4 Pump energy watts x pump operation time hrs x remaining days in year Controller energy watts x 24 hrs day x 365 Where the number of freeze days per year is found in Table 1 86 Appendix C The following Adjusted Standby Loss Factors were developed based on data contained in the Directory of Certified Water Heaters The table s purpose is to provide an easy reference for determining the adjusted standby loss rate of a particular water heater that has been exte
101. th facing is 180 This parameter may have monthly values Incidence angle modifier calculation cycles through Glazings Constant and Value s to indicate which of three possible methods is to be used to calculate the effect of incidence angle on FR TAU ALPHA One of the next three parameters will be available depending upon the selection the other two will be hidden If Glazings is selected the Fresnel equations are used with nominal glass properties and the number of glazings will have to be selected If Constant is selected the ASHRAE incident angle modifier constant will be required If Value s is selected either a single incidence angle modifier or the incident angle modifier value for every 10 degrees will be required If Value s is selected then select Ang Dep to enter either a single value or a value every 10 degrees in the dialog window 24 Chapter 3 Number of glazings can be 1 to 4 Values of the monthly average incidence angle modifier are calculated using the Fresnel equations with glass properties and the method described in Duffie and Beckman 1991 Inc angle modifier constant b is the parameter which provides the best fit in the equation K t 1 0 b 1 cos t 1 0 where K t is the ratio of the transmittance absorptance product at incidence angle t to the normal incidence transmittance absorptance product The constant b is determined experimentally as described in the ASHRAE Standard 93 77 collec
102. then used to describe the domestic water system If No is specified the following 6 parameters are ignored The liquid storage system should be selected if air collectors and a water to air heat exchanger are used to supply only domestic hot water Daily hot water usage is the average amount of hot water per day required at the set temperature Monthly values are allowed This parameter is visible only if Yes has been selected for domestic hot water parameter Water set temperature is the temperature to which domestic water is to be heated Monthly values are allowed This parameter is used only if Yes has been selected for domestic hot water Environment temperature is the temperature of the surroundings of the domestic water storage tank to which heat losses occur Monthly values are allowed This parameter is used only if Yes has been selected for domestic hot water 40 Chapter 4 UA of auxiliary storage tank is the product of the energy loss coefficient and surface area for the auxiliary tank in the solar domestic water heating system In a single tank system use the tank surface area above the heating element thermostat This parameter is visible only if Yes has been selected for domestic hot water Heat exchanger water flow rate is the mass flow rate of water from the solar preheat tank to the air water heat exchanger This parameter is visible only if Yes has been selected for domestic hot water Air water heat exch effectiveness is
103. tor test procedure 1977 This parameter is active only if Constant was chosen for the incidence angle modifier type Inc angle modifier value s are the value s of the collector incidence angle modifier K t as determined by the ASHRAE Standard 93 77 collector test procedure 1977 If a single value is used for this parameter then the incidence angle modifier is taken to be that constant value independent of solar incidence angle Alternatively values of this parameter may be specified for incidence angles between 0 and 90 degrees in 10 degree increments The incidence angle value s are used only if Value s was chosen for the incidence angle modifier type Collector flow rate area is the total mass flow rate of collector fluid through the collector array divided by the total collector array area This flow rate may be different from the flow rate at which the collector was tested Typical values of this flow rate are 11 Ib hr ft or 0 015 kg s m for liquids and 9 Ib hr ft or 0 012 kg s n for air Collector fluid specific heat is the specific heat of the fluid flowing through the collectors Properties can be found in the ASHRAE handbook of Fundamentals 1985 or in any heat transfer textbook For water use 1 0 Btu Ib F or 4 19 kJ kg K For air use 1 0 kJ kg K or 0 24 Btu Ib F Modify Test Values Yes No toggles to indicate if the next two parameters should be used to account for differences in the collector parameters due to diffe
104. ture f is the fraction of the total load including losses out the storage wall which is supplied by the solar system The remaining fraction must be met by an auxiliary source 4 7 Pool Heating Systems Pool solar heating calculations can be done for either indoor or outdoor pools as shown in Figure 4 7 The outdoor pool heating system can use solar energy in two ways Solar energy is absorbed directly by the water in the pool and it can be supplied by an optional solar collector system If a solar collector system is not being used set Number of collector panels in the collector parameter set to 0 Energy is lost from the pool by evaporation convection thermal radiation and conduction to the ground The evaporation loss can be eliminated by a pool cover The cover however reduces the amount of solar radiation absorbed by the pool Convection losses are reduced when a bubble type cover is used The covers are assumed to be transparent to infrared radiation so that radiation heat losses are not affected by the cover This pool heating system will provide estimates of the monthly energy loss from the pool based on the algorithms 57 Chapter 4 described by Sigworth et al 1979 If this information is already known from previous pool heating energy use the general solar heating system of Section 4 7 is an alternative way to estimate the contribution from a solar collector system Figue 4 7 Pool Heating System The thermal parameter
105. ture swing Fuel Efficiency of fuel usage 70 00 Location is the location where the system is located Existing city data can be viewed or changed or data for a new city added from the Data pull down menu Wall area is the surface area of the passive storage wall upon which solar radiation is absorbed Number of glazings cycles through 1 to 4 and is used to calculate both the angular dependence of the transmittance of solar radiation and the resistance to heat transfer from the outdoors to the exterior surface of the passive storage wall Monthly values are permitted Wall slope is the angle between the plane of the wall and the horizontal A vertical wall will have a 90 degree slope Wall azimuth is the deviation of the normal to the storage wall from south A due south orientation will have an azimuth of 0 degrees Due west and due east will have values of 90 and 90 respectively In the southern hemisphere a direct gain window facing the sun at solar noon i e facing north would have an azimuth angle of 180 Tau Alpha at normal incidence is the product of the glazing transmittance and wall absorptance for solar radiation at normal incidence Monthly values are permitted Wall thickness is the thickness of the solid portion of the passive storage wall i e excluding the glazing or night insulation Wall thermal conductivity is the thermal conductivity of the passive storage wall material Properties of common building materi
106. uid used in the collector test Properties of common materials can be found in the ASHRAE Handbook of Fundamentals 1985 or in any heat transfer textbook This parameter is used only if Yes is selected for modify test values 30 Chapter 3 3 4 One Axis Tracking Collector One Axis Tracking Collector Number of collector panels Collector panel area FR UL Test slope FR TAU ALPHA Test intercept Concentration ratio Axis slope Axis azimuth South 0 Incidence angle modifier Collector flowrate area Collector fluid specific heat Modify test values Test collector flowrate area Ib hr ft 2 Test fluid specific heat Btu Ib F Number of collector panels is multiplied by the area of a single collector panel to determine the total array area Collector panel area is either the gross or net aperture area of each collector panel The same gross or net aperture area that was used to determine FRFTAU ALPHA and FR UL must be used for this parameter The ASHRAE Standard 93 77 1977 collector test recommends the use of gross area FR UL Test Slope is the product of the collector heat removal factor FR and the collector overall heat loss factor UL FR UL is the negative of the slope of the straight line efficiency plot obtained from the ASHRAE Standard 93 77 1977 collector test FR TAU ALPHA Test Intercept is the product of the collector heat removal factor FR and the transmittance absorptance product TAU ALPHA at no
107. umber of points for which calculations are to be made Enter 10 and 50 respectively with No of points equal to five The dialog box should now appear like this Number of collector panels First value fi 0 iv Solar fraction Last value 50 iv Life cycle savings No of points 5 WM OK X Cancel When the Ok button is clicked F Chart will initiate calculations using five values of Number of collector panels ranging between 10 and 50 in this case 10 20 30 40 and 50 panels If the Smooth Curves box is checked a spline curve will be fit through the points A check in the Life Cycle Savings box will result in a plot of the savings as well as the solar fraction When the iv Spline fit calculations are completed the plot will appear in a separate window on the screen It is clear from the plot that the maximum life cycle savings occurs with about 17 panels and the corresponding solar fraction is about 43 Chapter 1 o Solar Fraction O Life Cycle Savings 6000 z E iz 2000 z S A u 2 s S E e 2000 2 l 5000 10000 10 20 30 40 50 Number of collector panels The look of the plot can easily be changed Double click on the plot and you have access to and can change many of the plot attributes Most of the system parameters may assume monthly values For example suppose you wish to consider the advantage of adjusting the slope of the collector at monthly intervals
108. ure by the conventional water heater The f Chart method for domestic water heating was originally developed for two tank systems However it is shown by Buckles et al 1980 that the f Chart method can also be used for single tank systems in which auxiliary energy is supplied to the upper portion of the solar preheat tank Relief Valves Tempering To Taps Preheat Collector Storage Tank Water Collector Storage Supply Heat Exchanger Figure 4 1 Two Tank Domestic Water Heating System 35 Chapter 4 The parameters for the active domestic hot water system are listed below along with their default values in English units A description of each parameter follows the parameter listing Active Domestic Hot Water System n x Location Water volume collector area Fuel Efficiency of fuel usage Daily hot water usage Water set temperature Environmental temperature UA of auxiliary storage tank Pipe heat loss Inlet pipe UA Outlet pipe UA Collector store heat exchanger Tank side flowrate area Heat exchanger effectiveness Location is the location where the system is located Existing city data can be viewed or changed or data for a new city added from the Data pull down menu Water storage volume collector area is multiplied by the number of collector panels and the panel area to determine the volume of stored water used for thermal storage In a single tank system use the volume below the heating ele
109. ut heat exchangers pumps or controllers Auxiliary energy must be supplied if the solar energy collected by the ICS system is insufficient to meet the water heating load COLLECTO Figure 4 9 Integral Collector Storage Solar Water Heater The monthly performance of an ICS system is estimated using the method of Zollner et al 1985 The thermal parameters and default values in English units are listed below followed by descriptions of the parameters 65 Chapter 4 ICS Water Heating System EE _ iol x Location No of units tested Glazing area per unit 16 70 SRCC heat loss coefficient SRCC net energy delivery Collector slope Collector azimuth South 0 Incidence angle modifier calculatic Number of glass covers Inc angle modifier constant Inc angle modifier value s Fuel Efficiency of fuel usage Daily hot water usage Water set temperature ICS unit tank volume UA of auxiliary storage tank Aux environmental temperature First month of use Last month of use Location is the location where the system is located Existing city data can be viewed or changed or data for a new city added from the Data pull down menu No of units tested is the number of integral collector storage units used in the SRCC test NOTE This parameter should not be changed without supplying modified values of the SRCC heat loss coefficient and SRCC net energy delivered Glazing area per unit is the aperture area of each ICS unit panel NOTE
110. water domestic hot water heat exchanger This parameter is used only if Yes has been selected for domestic hot water The thermal performance is calculated on a monthly basis The output in English units for the default parameters with 26 flat plate collectors and cp 0 24 appears below 49 Chapter 4 Thermal Output E ini x Solar Heat Dhw Aux 10 Btu 10 Btu 10 Btu 10 Btu Jan 1798 1869 2384 1487 Feb 2006 1524 2148 1087 Mar 2399 1236 2 368 7 44 Apr 24 94 7 11 2 277 2 61 May 27 89 3 27 2 341 0 00 Jun 28 46 0 83 2 255 0 00 Jul 29 52 0 37 2 326 0 00 Aug 28 06 0 68 2 330 0 00 Sep 24 07 2 43 2 263 0 00 Oct 21 02 6 28 2 351 2 54 Nov 14 38 10 95 2 287 8 17 Dec 14 05 16 53 2 378 13 87 Year 27441 94 73 27 709 60 37 Solar is the monthly total solar radiation incident on the collector surface Heat is the monthly total space heating demand Dhw is the monthly total water heating demand Aux is the monthly total auxiliary energy required to supply the space and domestic water heating demands f is the fraction of the space and domestic water heating demands which is supplied by the solar energy system The remaining fraction must be met by an auxiliary source 4 5 Passive Direct Gain Systems A schematic representation of a direct gain system is shown in Figure 4 5 During the month solar energy strikes the window surface and some of this energy is transmitted through the window and absorbed within the buildi
111. where the system is located Existing city data can be viewed or changed or data for a new city added from the Data pull down menu Average daily energy use is the monthly average daily energy demand of the process This 62 Chapter 4 energy demand is met by a combination of solar energy and conventional energy This parameter may have monthly values Average daily load flow is the average daily amount of stored fluid circulated or removed to supply the load In a closed loop system this will be the product of the rate at which fluid is circulated through the load heat exchanger and the average number of hours per day in which there is a load In an open loop system this is average daily amount of fluid removed from the tank This parameter may have monthly values Load heat exchanger effectiveness is the ratio of the actual to maximum heat transfer rates in the heat exchanger between the solar storage tank and the load in a closed loop system For an open loop system a heat exchanger does not exist and this parameter should be set equal to 1 0 Minimum useful temperature is the lowest temperature in which energy supplied to the load is useful Monthly values are permitted Liquid storage tank volume is the volume of stored liquid used for sensible heat storage of collected solar energy Tank liquid specific heat is the specific heat of the liquid in the storage tank Properties of common materials can be found in the ASHRAE Handbook

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