SR41/B This document is not a departmental publication. User`s
Contents
1. User s Manual November 1982 Assistance and Information K Ford Design Aids Engineer Solar Programs Office Sir Charles Tupper Building Riverside Drive Ottawa 0 2 613 998 3641 ee PSS SS This document is not a departmental publication Do not cite as a reference or catalogue in a library SRA1 B User Responsibility Users are responsible for the validity of the information generated by the ENERPUB program Consequently the program should not be used by those who do not comprehend the technical field to which this program applies Neither Public Works Canada nor any person acting on behalf of the department makes any warrenty or assumes any responsibility for accuracy completeness or usefulness of any information generated by this program TABLE OF CONTENTS INTRODUCTION THE ENERPUB COMPUTER PROGRAM D 2 1 System Configurations 2 2 System Operating Strategies Space Heating 2 2 1 Solar Energy Collection Strategy 2 2 2 DHW Heating Strategy 2 2 3 Space Heating Strategies 2 2 3 1 Space Heating Strategies system type 0 2 2 3 2 Space Heating Strategies system type 1 2 2 3 3 Space Heating Strategies system type 2 2 2 3 4 Space Heating Strategies system type 3 2 3 System Operating Strategies 011 Tank Heating 2 4 Tutorial Session SYSTEM2. m Cp 1 exp AF U m F U m Cp 1 3 5 Calculation of Pipe Heat Loss Coefficient The thermal conductance of pipe insulation is given by U 2n kL in W C 2t d gn where d is the outside pipe diameter mm t is the thickness of the insulation mm L is the length of pipe m k is the thermal conductivity of the insulation in W m C Kibreglass 0 0346 W m C olyurethane 0 0245 W m C 36 4 DESCRIPTION OF PROGRAM OUTPUT 4 1 Thermal Analysis Results The thermal analysis of the system is printed in monthly intervals with a yearly summary printed at the end The results are an estimate of the system performance of a properly designed and installed system The program cannot account for improperly insulated piping pump failure or other system faults The output values are SOLAR INCIDENT GJ Total solar radiation incident on the collector over the time period SOLAR COLLECT GJ Solar energy transferred from the collector to the storage SOLAR DELIVERED GJ Solar energy delivered to the space heating and hot water loads not including heat pump contribution HT PUMP DELIVER GJ Energy delivered by the heat pump to the space heating load SPACE HT LOAD GJ Space heating load i e auxiliary energy that would have to be supplied to meet the space heating load if there were no solar heating system AUX SPACE HT GJ Auxiliary energy r
3. 1810 woe 0 ANGLL OF 5 95 00 GRLLATAGLON SOUTh 0 uEGPLz3 0 00 m 2055 CouLeCrTer ATLL 42 4 100 00 CCilrCiCe 0 2 55 neVULRid CULL STCuAGE 12 DIFFoniNor 1 70 ECwra OF PUMPS 152 CCi rCICa 0 FLCW 11 82 lt 60 FR TAU ALPHA ADJUSTED lt lt lt lt lt lt lt lt 0 710 FR UL 40005 W H2 C ceca lt lt lt osos 3291 INCIDENT ANGLE NODIFibiswe ee 0 100 COLLLC 5 CEFLCLIVENESS ewe 1 000 SiChAGe DALA V2LUXsz CoLz niga 5 900 Zz2 PuLrAiURZE 2 28 00 SUnaCUNLLZSNG LEXPERATURL c 2 2 4 7100 0 LCP hiki LOSS 44 300 00 SILE Huhai LOSS CCZFP W L eo lt lt lt 6 00 00 LOSS lt lt lt lt 300 00 OF SinaziFicATICh Tank 5 1 5205 FOR COLLECTOR 1 5 0 F n BUILCING aEQUEN 1310 1 HlhiZ2Uh ALLGWaELS StTusaGo TLd2 C 28 00
4. Collector does not operate Calculate building supply pipe heat loss Calculate heat delivered to DHW Calculate water inlet temperature to building Calculate max possible solar heat to load Qsotar Can any solar heat be delivered to load M Y f Calculate building return pipe heat loss Calculate frac tion of hour that system operates Can solar heat meet the full load Calculate load i not met by solar Qus Q solar Q10ad 41 42 Does the system have a heat pump Is the heat source ambient air Teource Calculate heat delivered by hea pump for full r p T source Calculate heat delivered by heat pump for full hour Qh Partion heat load between solar and heat pump Auxiliary heat 04 Calculate heat 1055 from load return pipe 43 Calculate inlet temperature to tank Calculate new storage temperature Sum heat flows Has all the weather data been used Go to 2 Output system performance Calculate Economics Type S to stop Go tol 44 and the weather conditions the collector performance be determined See Section 5 4 for a detailed description of the algorithm for collector performance If the collector operates for the hour th
5. 89 UNIT CCST s10ahui H3 eeeceecesenesose 7122 51 UNIT CCZ2 OF FUEL AI PRESENT GJ e 10 000 62 X 1 CF rNzhul 13 9 13 u 13 0 15 0 15 9 19 9 10 0 10 0 10 0 16 0 19 9 19 9 10 19 0 10 9 10 0 10 0 19 9 19 0 14 0 15 If this is the first run the solar radiation on the tilted collector must be calculated To process the weather data the program will ask the user for the latitude of the location ENTER LATITUDE OF LOCATION DzG 45 PROCESSING WEATHER If on successive runs the collector slope collector azimuth the first day of the period do not change then the program will skip the weather data processing section After the weather data has been processed the simulation starts When the simulation is complete the results are printed SIMULATION STARTS seen COLLECTOR AREA 100 00 2 ENERGY ANALYSIS SUMMARY STCRAGE VOLUME 7 50 M3 SOLAR SOLAK SOLAR HT PUMP SPACE AUX WATER AUX INCIDENT COLLECT DELIVER DLLIVER LOAD SPACE HT LOAD WATER HT GJ GJ GJ GJ GJ 2 GJ GJ GJ GJ 4 n n 16 TCTAL INPUT
6. 0 79 UNIT COST COULLECTUK 3 2 230 80 UNIT COST OF STORAGE 3 MJ u wws s esu s 122 81 UNIT COSI Or FUEL AT PRESENT 3 62 10 000 82 INFLATION RATE OF ENERGY 0 130 0 130 0 130 92139 0 130 0 100 0 100 0 100 0 100 0 100 0 100 0 1900 0 100 0 100 0 100 0 100 0 100 0 100 u 100 0 100 65 9 NOMENCLATURE Tr gt Cruel main heat pump coefficients collector area heat pump coefficients incident angle modifier first year fuel cost yr first year maintenance cost yr coefficient of performance specific heat KJ kg C salvage value total cost of the solar system domestic hot water load litres total heating load over system life GJ heat exchanger factor collector heat removal factor collector transmission absorption coefficient collector heat loss coefficient W m C fraction solar measured hourly solar radiation KJ hr m beam hourly solar radiation KJ hr m beam hourly solar radiation on a tilted surface KJ hr m diffuse hourly solar radiation KJ hr m diffuse hourly solar radiation on a tilted surface KJ hr m extraterrestrial hourly solar radiation KJ hr m heat pump reflected hourly solar radiation KJ hr m 66 solar heat exchanger fuel inflation rate internal heat gain KJ clearness index loan interest rate loan period years life cycle unit c
7. BUILDING 40 41 M 43 45 46 BUILSING 050 FUR JEATING LAN W aewesscoscsuzssewse 0 SLORAGE SUILDING HX 55 0 700 RALE CF LUAL 3000 DIRECT SULAR GAIN FACTCA 42 0 00 iNLOOA DosSIiGN TEMPERATURE 20 00 iNTLhNan HOURLY HEAT GAIN SCHEDULE Kd 0 9 9 0 9 1800 3000 2700 5400 3596 1800 3590 3600 2790 2700 1800 16200 6300 2790 2700 2700 1500 1500 19 HATER LOAD DATA ee me ee ee m a 50 WATER MAIN TEMPERATURE 28 00 51 DESIRED WATER TEMP 59 00 2 DHW 55 1 00 53 HOURLY HOT WATER SCHEDULE LITRES 0 0 0 9 0 0 0 0 0 100 100 200 200 200 200 100 100 100 100 0 0 0 0 0 PIPING DATA 60 PIPE HEAT LOSS COEFF COL RETURN W C 0 00 61 SURROUNDING TEMPERATURE COL RETURN 20 0 62 PIPE HEAT LOSS COEFF COL SUPPLY W C 0 00 63 SURROUNDING TEMPEBATURE COL SUPPLY C 20 0 64 PIPE HEAT LOSS COEFF BDG SUPPLY W C 0 00 65 SURROUNDING TEMPERATURE BDG SUPPLY 20 0 66 PIPE HEAT LOSS COEFF BDG RETURN 0 00 67 SURROUNDING TEMPERA
8. in litres Piping Parameters 60 PIPE HEAT LOSS COEFF COL RETURN W C The heat loss per degree Celsius of the return piping from the col lector i e region 1 see Section 3 5 61 SURROUNDING TEMPERATURE COL RETURN The air temperature surrounding the piping of parameter 60 Use a value of 100 for outdoor piping A value of 200 should be used for buried piping 62 PIPE HEAT LOSS COEFF COL SUPPLY The heat loss per degree Celsius of the supply piping to the collector i e region 2 see Section 3 5 63 SURROUNDING TEMPERATURE COL SUPPLY C The air temperature surrounding the piping of parameter 62 100 for outdoor piping 200 for buried piping 64 HEAT LOSS COEFF BDG SUPPLY W C The heat loss per degree Celsius of the supply piping to the building i e region 3 see Section 3 5 65 SURROUNDING TEMPERATURE BDG SUPPLY C The air temperature surrounding the piping of parameter 64 100 for outdoor piping 200 for buried piping 66 PIPE HEAT LOSS COEFF BDG RETURN C The heat loss per degree Celsius of the return piping from 28 67 70 71 72 73 74 75 76 77 78 the building i e region 4 see Section 3 5 SURROUNDING TEMPERATURE BDG RETURN W C The air temperature surrounding the piping of parameter 66 100 for outdoor piping 200 for buried piping Economic Parameters SYSTEM LIFE YEARS The number of years for economic analysis i e sola
9. will ask for the title of the run The title has no effect on the program calculation but merely serves as a method for distinguishing between computer runs The title can be up to 72 characters in length on a single Tine ENTER TITLE OF RUN run After the title has been entered the simulation starts The program will print the title and the input parameters SAMPLE RUN iNPUI LISTING GENERAL SYSTEM DATA 1 SIMULATION BEGINS IN 1970 2 SIMULATION PERIOD 5 365 3 CF THE PEBIOD 1 365 1 4 DETAILED PRINT OUT NO 0 YES I HK INTERVAL 0 5 STARTING HCUR CF FRINT INTERVAL 0 1 0 6 TILTED ANGLE CCLLECTO8 LEGREES 55 00 7 COLLECTOR ORIENTATION SCUTH 0 DEGBEES 0 00 COLLECICK gt 11 2011 105 Talia 12 REVULALED CCLl SiUCraGz LikFint dCi C 13 CF 5 152 CCLLzclus abah 2 14 FLOW His CAFACilY 1 7 60 15 05 0 710 16 FR UL ADJUSZELI ea oec 3 910 17 50 Fur INCIDENT AOLLELE 9 100 15 5105446 irLCTiVL
10. 6300 2700 2700 2700 1800 1800 13 WATER LOAD DATA 50 WATER MAIN TEMPERATURE 2 6200 51 DESIRED HOT WATER TEMP C eee eee ee 40 00 52 DHW HX 55 0 50 53 HOURLY WATER SCHEDULE LITRES 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 PIPING 60 PIPE HEAT LOSS CCL RETURN W C 0 00 61 SURROUNLING TEMPERATURE COL RETURN 20 0 62 PIPE HEAT LOSS COEFF COL SUPPLY Ww C 0 00 63 SURROUNDING TEMPERATURE CCL SUPPLY 20 0 64 PIPE HEAT LOSS CCEFF EDG SUPPLY W C 0 00 65 SURROUNDING TEMPERATURE BDG SUPPLY 20 0 66 PIPE HEAT LOSS CCEFF ECG RETURN W C 0 00 67 SURROUNDING TEMPERATURE ETUEN 20 0 UCCKUMIC Lala ALLENS eese wees mE lt Jl LeAR YEARS ss we e ene i 20 72 15 LALD CFE LOAN A owen we ULO 75 hhIL IURA 2152001 2 6 10 JLI 74 FEALD 205 lt 3 5 08530 5 FIXED Of tical PURE Ad secs ca 21606 YSARLY HaaNTENebCe CCST CF COMP 50 77 YEARLY COSI Or i Yh 54 75 SALVAGE VaLUL END OF FLniCD 4 9 T9 ZOST OF CGLLECTLA i52 e verna
11. Ta Hr FRU If Te is greater than the inlet temperature the collector is assumed to operate for the full hour If Te is less than the inlet temperature the collector does not operate The heat collected by the collector 15 1 9 FRU Area T 4 collector outlet temperature is 9 52 5 5 Algorithm for Heat Pump The energy delivered by the heat pump 9 is estimated by using correlation between energy output and the source or heat pump evaporator temperature Ta The energy consumed by the heat pump Php is estimated a similar manner E 2 Qhp a T 4 2 21 5 where 41 b4 bos 5 are correlation coefficients The correlation coefficients can be estimated from the heat pump performance curve available from the heat pump manufacturer Alternatively performance data points can be entered into the program and the program will generate the coefficients using a least squares analysis The heat pump operation is assumed to be steady state for each one hour time step of the simulation This implies that the temperature of the heat source whether the solar storage tank or ambient air is constant over the hour or the fraction of the hour needed to meet the load The coefficient of performance COP of the heat pump is defined as COP Qnp Php A heat pump can only operate within specific ranges of
12. ELECTRIC RESISTANCE REFERENCE SYSTEM OVER SIMULATION GJ 451 449 ENERGY SAVING 36 41 SEASONAL PERFORMANCE FACTOR 1 57 HOURLY ENERGY INPUT MJ 1792487 ENERGY GAINED BY STORAGE TANK GJ 0 036 ANALYSIS PRESZNT WORTH AUXILIARY ENERGY INCL 92614 63 AUXILIARY ENERGY NOT INCL 1 27776 34 LIFE CYCLE UNIT CCST LUC 2 6 10 257 SCIAR LUC 8 450 CHANGE PARAMETER NUMBER 5 The program will return with the prompt TO CHANGE PARAMETER TYPE CODE NUMBER If the user is finished type S to stop otherwise modify the The input parameters as necessary and re run the program The simulation procedure for 011 tank heating system is shown below user should take note of the parameters that should be modified ENTER SOLAR SYSTEM TYPE DO YOU STANDARD SOLAR SPACE HEATING NO HEAT PUMP HEAT PUMP IN SERIES WITH SOLAR SUPPLY HEAT PUMP IN PAKALLEL WITH SOLAR SUPPLY SOLAR ASSISTED HEAT PUMP ONLY OIL TANK HEATING NO HEAT PUMP WISH ECONOMIC ANALYSIS Y N ARE THE PIPES OR TANK BURIED 2 Y N INSTRUCTIONS L R 10 5 CHANGE 11 ENTER NEW 55 TO CHANGE 51 ENTER 55 CHANGE 20 ENTER NEW 5 TO CHANGE 22 ENTER NEW 100 TO CHANGE 23 ENTER NES 300 TO CHANGE 24 ENTER NEW 600 TO CHANGE 25 ENTE
13. FR UL W M2 C eee wie ee 3 91 BO FOR INCIDENT ANGLE MODIFIERS 2 270 100 COLLECTOR STORAGE HX 552 1 000 STORAGE DATA 21 22 29 STORAGE VOLUME COLL AREA 3 2 2 lt lt lt lt lt lt 0 075 STARTING TEMPERATURE 2 20 00 SURROUNDING TEMPERATURE 20 0 TOP HEAT LOSS COEFF 0 00 SIDE HEAT LOSS COEFF 9 00 BOTTOM HEAT LOSS COEFF 90 00 OF STRATIFICATION TANK 5 5 1 SEG FOR COLLECTOR RETURN INTO TANK 1 SEG FOR BUILDING RETURN INTO 1 MINIMUM ALLOWABLE STORAGE TEMP 4 00 HEAT PUMP DATA V M 30 31 32 LOWER LIMII OF EVAPORATOR TEMP lt lt lt HIGHER LIMIT OF EVAPORATOR TEMP COEFFICIENTS CQ CP OF HEAT PUMP BUILDING DATA 40 41 42 43 45 46 WATER 50 51 52 53 0 0 35 0 STORAGE BUILDING EFFECTIVENESS scccesan DIRECT SOLAR GAIN FACTOR M2 lt lt lt lt INDOOR DESIGN TEMPERATURE C lt INTERNAL HOURLY HEAT GAIN SCHEDULE KJ 0 9 700 MIN C PACITANCE RATE OF LOAD H W C 3000 20 00 0 0 0 0 0 1890 3600
14. Vol 23 No 2 Evaluation of Models to Predict Insulation on Tilted Surfaces 5 deWinter F Solar Energy Vol 17 Heat Exchanger Penalties in Double Loop Solar Water Heating Systems 6 Klein 5 A Design Procedure for Solar Heating Systems Ph D Thesis University of Wisconsin Madison 62 8 INPUT DATA WORKSHEET L 5 10 ENERPUB Commands TO OBTAIN DATA LISTING TO RUN PROGRAM WITH LISTING TO CHANGE SYSTEM TYPE TO STOP SESSION HANGE PARAMETER TYPE CODE NUMBER ENERPUB Input Data With Default Values GENERAL SYSTEM DATA oe SIMULATION BEGINS IN 1970 SIMULATION PERIOD 15 365 DAY1 OF THE PERIOD 1 365 1 lt c coe reme n 1 DETAILED PRINT OUT NO 0 YES I HR INTERVAL 0 STARTING HOUR OF PRINT INTERVAL 0 1 0 TILTED ANGLE OF COLLECTOR DEGREES 55 00 COLLECTOR ORIENTATION SOUTH 0 DEGREES 0 00 COLLECTOR DATA 10 11 12 13 14 15 16 17 18 te ee ee COLLECTOR AREA 2 100 00 MAXIMUM OUTLET TEMP 2 lt lt lt 98 DIFFERENTIAL 1 70 PUMP POWER COLLECTOR AREA 2 0 FLOW RATE HT CAPACITY 2 69 lt 0 710
15. 1971 1971 1971 1971 1971 gt ov Ss x Prince George e Edmonton Vancouver The Pa Pu Saskatoon gt Medicine eSwift Cutrent Brandon MAP Canadian Weather Stations Frobisher Bay 7 hurchill 7 Goose ay Gander st Step CN Sept Iles lt lt gt 2 Charlo Sydney Riviere du Loup X 4 w Chatham CS 339 Charlottetown m O9 Winnipeg Kapuskasing STN 6 Moncton e Quebec Fredericton ze Truro eVal d Or Saint John OF Halifax Sault te i A 9 Ste Marie 2 Sherbrooke Yarmouth a sudbury Kingston TE 32 Fredericton 45 9 1971 Charlo N B 48 0 1971 D Chatham N B 47 0 1971 D Moncton N B 46 1 1971 D St John N B 45 3 1971 D Charlottetown P E I 46 3 1971 D Truro N S 45 4 1971 Halifax N S 44 7 1971 M Sydney N S 46 2 1971 D Yarmouth N S 43 8 1971 D St John s 47 6 1971 Nfld 49 0 1971 D Stephenville Nfld 48 5 1971 D Goose Bay 53 3 1971 3 3 Ground Temperature Atmospheric Environment Service 5 has been measuring the ground soil temperatures for many locations across Canada Of the locations listed in Section 3 2 only 16 measure soil temperature The soil temperatures at depths of 0 5 m
16. 63 65 67 is the average temperature of the fluid fm Tein Trout The outlet fluid temperature can be calculated from the pipe heat Toss and the mass flow rate Tro 19 7 0105 2 Equations 1 and 2 are dependent one another that is they both contain the same two unknowns Dros and Teo By combining the equations the unknowns can be solved exactly UA 055 7 UA ipe 1 T pipe 2m 51 5 4 Algorithm for Solar Collector Performance The instantaneous performance of solar collectors is represented by the standard Hottel Whillier Bliss model of Fata and Fou The program assumes that both these collector characteristics are independent of temperature and solar radiation If collector to storage heat exchanger is used the Fata and modified according to the method of DeWinter 5 Fata FRU where E mC m C Fal 1 and the on a value means that it includes the effect of the heat exchanger For each hour the reduction in solar transmission of the collector for non normal angles of incidence is calculated This reduction K is given by 1 1 1 where is the incident angle modifier 9 is the incident angle of the beam radiation on the collector To determine if the collector will operate for a given hour the stagnation temperature is calculated
17. INPUT PARAMETERS 1 Definition of Input Parameters 2 Weather Data and Map 3 Ground Temperature 4 Modification of Collector Test Data B C29 C9 CO CO CO DESCRIPTION OF PROGRAM OUTPUT 4 1 Thermal Analysis Results 4 2 Economic Analysis PROGRAM ALGORITHM Overview of Program Operation Algorithm to Process Weather Data Algorithm for Heat Pump Algorithm for Stratified Storage Tank Algorithm for Economic Analysis PROGRAM STRUCTURE REFERENCES INPUT DATA WORKSHEET NOMENCLATURE Calculation of Pipe Heat Loss Coefficient 5 1 5 2 5 3 Algorithm for Calculation of Pipe Heat Loss 5 4 Algorithm for Solar Collector Performance 5 5 5 6 5 7 h 0 WP C2 Lod ON FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 LIST OF FIGURES Solar Heating System Schematic No Heat Pump system type 0 Solar Heating System Schematic Heat Pump in Series with Solar Supply system type 1 Heat Pump in Parallel with Solar Heating System Schematic Solar Supply system type 2 Solar Heating System Schematic Heat Pump Supply Only system type 3 Oil Tank Heating System system type 4 ENERPUB Flow Chart ENERPUB Program Structure 1 INTRODUCTION ENERPUB computer program developed Enermodal Engineering Limited for Public Works Canada can be used to simul
18. Supply system type 1 Figure 3 Solar Heating System Schematic Pump in Parallel with Solar Supply system type 2 Figure 4 Solar Heating System Schematic Heat Pump Supply Only system type 3 0 3 15 6 Butzeay xue 110 6 eJn5L4J 2 2 1 Solar Energy Collection Strategy If the collector inlet fluid temperature is lower than the average collector plate temperature solar energy can be collected and transferred to the storage tank If the collector outlet temperature approaches the boiling point the system will not operate this case either the collectors would be drained or solar energy dumped through the pressure relief valve 2 2 2 DHW Heating Strategy Domestic hot water preheating is accomplished by passing city mains water through a heat exchanger contained in the top of the storage tank The water if not warmed to the desired water temperature is heated by the conventional water heater Note that the heat exchanger only operates when there is a water demand i e there is no recirculation of the water If the DHW heating load forms a large portion of the total heating load greater than 20 this model is not suitable and will not provide satisfactory results 2 2 3 Space Heating Strategies 2 2 3 1 Space Heating Strategy system type 0 No heat pump is used in this system If the building requires heat water from the storage tank is ci
19. and 1 5 m for these locations are given below For further information on soil temperatures the user is referred to the A E S publication Soil Temperature Averages 1958 1978 by D W Phillips and D Ashton Report CLI3 79 Prince George B C Soil temperature in C at depths of 0 5 m and 1 5 m J p M A M J J 5 0 N 1 3 1 0 0 8 1 5 6 0 10 8 133 141 12 2 8 6 4 6 4 2 3 3 2 7 24 32 6 0 8 5 10 3 1066 9 7 7 7 gt 33 Vancouver Summerland B C 17 8 21 1 22 6 14 2 17 4 19 8 13 2 10 6 m or Resolute Swift Current Sask Saskatoon Sask Winnipeg Man Kapuskasing Ont 34 Toronto Ont Ottawa Ont 18 3 13 1 Val D Or Que Fredericton N B 15 7 13 8 lt Charlottetown P E I 15 7 12 8 srsr gt gt norm On e C lt sr Truro N S St John s Nfld Goose Nfld 35 3 4 Modification of Collector Test Data The performance of a solar collector is dependent on the flow rate If the collector flow rate for the proposed system is different from that used when the collector was tested the FRU terms must be modified adjusted pe Fat test FRU adjusted r FRU test where m 1 expL AF U m 1
20. radiation on horizontal surface is calculated by lt 5 cos 6 where cos 15 cosine of the zenith angle angle between the beam and the vertical cos cos cos 6 cos sing sins is the latitude of the location w is the hour angle The diffuse solar radiation be estimated using correlation by Orgill and Hollands 2 0 1769 H if 0 75 lt K 1 55699 1 84013 _ df 0 35 lt s 0 75 1 0 248857 if 0 0 s 0 35 where H is the measured hourly solar radiation 48 is the ratio of measured solar radiation to the extraterrestrial solar radiation H Hox The beam radiation Hj is simply the total measured solar radiation minus the diffuse radiation 5 9 The next step is to calculate the ratio of beam radiation on the tilted surface to that on the horizontal surface R Ry cos 5 e where cos is the cosine of the angle of incidence of beam radiation between the beam and the normal to the surface cos sin 6 sin 4 cos cos 6 cos 4 cos s cos cos 8 sin sin s cos y cos cos 6 sin sin y sin w Y is the azimuth angle measured from south east is positive west is negative Thus the beam solar radiation on the tilted surface is Hor Rp The diffuse solar radiation component on the tilted surface is estimated using th
21. the solar heating system plus the cost of auxiliary energy over the system life at present prices second value is the cost of installing and maintaining the solar heating system over the system life at present prices 38 The LIFE CYCLE UNIT COST is the average price paid for building heating over the system life in present prices includes solar heating system That is the first value of present worth divided by the total energy load of the building over the system life The SOLAR LUC is the average price paid for the solar energy contribution over the system life in present dollars 39 5 PROGRAM ALGORITHM This section describes the thermodynamic models and equations used to simulate the solar heating system 5 1 Overview of Program Operation The basic assumption in the program is that for the purpose of ther mal performance prediction all variables including solar radiation ambient temperature and system energy flows can be considered constant for each hour The calculation flow chart is shown in Figure 6 The first step in the program is the input from a data file of the default values of the input parameters The user is then able to modify the input parameters as necessary After all the input parameters are set the user initiates the simulation by typing R If processed weather data is not available the solar radiation on the tilted surface is calculated from the horizontal so
22. 2700 5400 4500 1800 3600 4500 3609 2790 2700 1890 16200 6300 2700 2700 2700 1800 1800 LOAD DATA WATER MAIN TEMPERATURE 4244 DESIRED WATER TEMP 22 2 lt lt 5 lt lt lt lt DHW HX EFFECTIVENESS lt lt lt HOURLY HOT WATER SCHEDULE LITRES 0 0 9 0 0 0 9 0 0 0 0 9 0 0 9 0 0 9 9 0 PIPING DATA 60 61 62 53 64 65 66 67 PIPE HEAT LOSS COEFF COL RETURN W C ene SURROUNDING TEMPERATURE COL RETUBN PIPE HEAT LOSS COEFF COL SUPPLY W C SURROUNDING TEMPERATURE COL SUPPLY PIPE HEAT LOSS COEFF BDG SUPPLY SURROUNDING TEMPERATURE BDG SUPPLY C PIPE HEAT LOSS COEFF BDG RETURN W C cee SURROUNDING TEMPERATURE BDG RETURN 6 00 40 00 0 0 9 0 0 50 92 90 20 0 0 00 20 0 0 00 20 0 0 00 20 0 63 64 ECONOMIC DATA 70 SYSTEM LIFE 5 29 71 TERM OF LOAN 5 22245555255 20 722 INTEREST RATS OF 0 5 545545 556 2 4 Oa 100 73 RATE OF RETURN DISCOUNT 0 100 74 FIXED COST OF SOLAR COMPONENZS 830 75 FIXED COST OF HEAT PUMP 5 2180 76 YEARLY MAINTENANCE COST OF SOLAR COMP 3 Y 50 77 YEARLY MAINTENANCE COST Or HP YIR e 59 78 SALVAGE VALUE AT END OF PERIOD
23. ET NORTH WATERLOO ONTARIO 822 519 884 6421 LIQUID BASED SOLAR HEATING SYSTEM WITH HEAT PUMP AND STRATIFIED TANK 11 program will prompt the user for system characteristics concerning system type and whether the pipes or tank are buried ENTER SOLAR SYSTEM 9 WN e DO YOU STANDARD SOLAR SPACE HEATING NO HEAT PUMP HEAT PUMP IN SERIES WITH SOLAR SUPPLY HEAT PUMP IN PARALLEL WITH SOLAR SUPPLY SOLAR ASSISTED HEAT PUMP ONLY OIL TANK HEATING NO HEAT PUMP WISH ECONOMIC ANALYSIS Y N ARE THE PIPES OB TANK BURIED Y N The program will then print the message INSTRUCTIONS L TO OBTAIN DATA LISTING TO RUN PROGRAM WITH LISTING C TO CHANGE SYSTEM TYPE 8 STOP SESSION OR TO CHANGE PARAMETER TYPE CODE NUMBER 12 types np S a number Normally At this point the user has several choices of commands If the user the program will list 11 the input parameters with their present values the program will list all the parameters and start the simulation the system type and ground temperatures can be changed the computer session will be stopped the program will ask for the new value of this parameter the user will want to modify the input data The code numbers are listed at the beginning of each line for each variable When the input data is correct the user should type The program
24. NLO2 1 000 0 S1084GL 85 12 lt 0 0975 21 STARK Laws RAL 20 SUBB UNLING LEBPSRATURE 6 2040 23 HERG LOSS 0500 256 5115 Heke LCS5 COSRP 25 bUOTIGh HAAI i955 CUEFF 008 t OF 1 27 SiGe COLLZCIOK 2810 8 6 1 lt 8 556 8 PUR EVELLING wwe wee 1 29 HIBINUU 1 S105aGL lt lt 4 00 HEAT EUMP DATA 30 LOWER LIMIT OF EVAPORAICR TEMP C eee 0 0 31 HIGHER LIMIT 35 0 32 COEFFICIENTS CQ CP OF HEAT PUMP z 5 000 448 000 15473 000 0 000 103 006 5767 000 BUILDING DATA 40 BUILDING UA COEFF lt lt lt lt lt lt lt lt lt lt 1000 0 41 POWER FOR HEATING FAN W ecceccccncceccacce 0 42 STORAGE BUILDING HX EFFECTIVENESS 0 700 43 MIN CAEACITANCE RATE OF LOAD HX W C 3000 44 DIRECT SOLAR GAIN FACTOR 2 0200 45 INDOOR DESIGN TEMPERATURE 20 00 INTERNAL HOURLY HEAT GAIN SCHEDULE 0 0 0 0 0 1800 3600 2700 5400 4500 1800 3600 4500 3600 2700 2700 1800 16200
25. R 300 CHANGE 53 000000 10 CHANGE 29 ENTER 28 TO CHANGE 21 ENTER NEN 28 10 CHANGE 50 ENTER NEW 28 CHANGE PARAMETER 17 OBTAIN DATA LISTING RUN PROGRAM WITH LISTING CHANGE SYSTEM TYPE STOP SESSION PARAMETER TYPE CODE NUMBER VALUE OF PARAMETER 11 PARAMETER TYPE CODE NUMBER VALUE OF PARAMETER 51 PARAMETER TYPE NUMBER VALUE OF PARAMETER 20 PARANETER CODE NUMBER VALUE OF PARAHETER 22 PARAMETER TYPE CODE NUMBER VALUE OF PARAMETER 23 PARAMETER TYPE CODE NUMBER VALUE OF PARAMETER 24 PARAMETER TYPE CODE NUMBER VALUE OF PARAMETER 25 TYPE CODE PARAMETER NUMBER ENTER 24 VALUES OF WATER LOAD LITREES 0 0 0 100 100 200 200 200 200 100 100 100 1000 00 0 0 PARAMETER TYPE CODE NUMBER VALUE OF PARAMETER 29 PARAMETER TYPE CODE NUMBER VALUE OF 21 PARAMETER CODE NUMBER VALUE OF PARAMETER 50 TYPE CODE NUMBER ENTER TITLE OF sample run 2 1 18 SABPLE 82 15 wee INPUT LISTING GENesaL SYSTEM mo v n SIMULATION 15 1970 SIMULATION 1 365 DAYI CF PERIOD 1 595 4 4 44 1 DETAILED NC U YeSSielin ahirnVal 0 gt t nrisG HOUR
26. RATE OF LOAD HX W C The minimum flow rate times heat capacity of the fluid on either side of the building heat exchanger This value is usually one to three times the value of the building heat loss coefficient DIRECT SOLAR GAIN FACTOR M2 The area of south facing window used for passive solar heating the south facing window area is significantly greater than 54 of the floor area the passive solar contribution could be significantly overestimated and the program is not suitable INDOOR DESIGN TEMPERATURE C The average indoor building temperature INTERNAL HOURLY HEAT GAIN SCHEDULE KJ 24 values of the hourly building internal heat gain from electric lights appliances people etc Water Load Parameters WATER MAIN TEMPERATURE C i The average water or oil supply temperature from the city mains or well In general this value is equal to the average ambient temperature over the year DESIRED HOT WATER TEMP C The desired hot water supply temperature i e temperature setting of auxiliary water heater For the oil tank heating system this parameter would be equal to the maximum allowable oil temperature see Parameter 11 1 27 52 DHW HX EFFECTIVENESS effectiveness of the DHW heat exchanger in the storage tank must be between 0 and 1 53 HOURLY HOT WATER SCHEDULE LITRES 24 values of the hourly hot water heating load or 011 removal rate
27. TURE BDG RETURN 20 0 SIMULATION 5 75 doo kc deo EEE KEKE COLLECTOR AREA 100 00 42 ENERGY ANALYSIS SUMMARY STORAGE VOLUME 500 00 SOLAB SOLAR SOLAR PUMP SPACE AU WATER AUX PUMP INCIDENT COLLECT DELIVER DELIVER LOAD SPACE HT LOAD WATER HT POSER GJ GJ GJ 64 GJ GJ 64 GJ GJ 5 20 TOTAL ENERGY INPUT ELECTRIC RESISTANCE REFERENCE SYSTEM OVER SIMULATION PERIOD GJ 855 771 ENERGY SAVING 28 88 PERCENT SEASONAL PERFORMANCE FACTOR 1 41 HOURLY ENERGY INPUT 234 883 ENERGY GAINED BY STORAGE TANK 62 0 000 EARNING 3 HEATER IS REQUIRED IN STORAGE TO PREVENT DROPPING BELOW MINIMUM TO CHANGE PARAMETER TYPE CODE NUMBER see page 55 for description 3 21 SYSTEM INPUT PARAMETERS The following sections describe the parameters used in the ENERPUB computer program The default values of these parameters are given in Section B Make sure that input values are in the correct units un 3 1 Definition of Input Parameters General System Parameters SIMULATION BEGINS IN YEAR The year for which weather data is being used See Section 3 2 for values SIMULATION PERIOD DAYS The number of days that the s
28. arameters 30 31 32 LOWER LIMIT OF EVAPORATOR TEMP The lowest temperature of the heat pump source cold side for which the heat pump will operate HIGHER LIMIT OF EVAPORATOR TEMP The highest temperature of the heat pump source cold side for which the heat pump will operate COEFFICIENTS CQ CP OF HEAT PUMP Three coefficients of the heat supplied by the heat pump as a function of the source temperature and three coefficients of the heat consumed by the heat pump as a function of the source temperature in units of KJ HR i e hp at aot 2 biT 4 If these coefficients are not known the program will ask for data points on heat pump performance curve The user will have to enter at least three values of source temperature C heat pump energy output W and heat pump energy input W With these data points the program will generate the required coefficients Building Parameters 40 BUILDING UA COEFF The building heat loss coefficient as calculated according to the ASHRAE Handbook of Fundamentals including infiltration 26 41 42 43 44 45 46 50 51 POWER FOR HEATING PUMPS The power necessary to operate pumps 3 and 4 and the building air circulation fan if used STORAGE BUILDING HX EFFECTIVENESS The effectiveness of the heat exchanger between the storage and the building HX must be between 0 and 1 MIN CAPACITANCE
29. ate the performance of liquid based seasonal short term storage solar space heating systems with or without a heat pump The program can also simulate the performance of a solar heating system used to heat oil in oil storage tanks ENERPUB is not suitable for simulation of solar domestic hot water systems specifically because of the restrictive heat exchanger models The ENERPUB program has many advantages over other solar simulation programs Because performance calculations are made for each simulated hour the program results are potentially more accurate than those of programs using a monthly calculation procedure such as FCHART addition the ENERPUB program can simulate a wider range of parameters than programs restricted by monthly average correlation equations Several of the models in the ENERPUB program were adapted from WATSUN models WATSUN is an hour by hour computer program developed by the University of Waterloo ENERPUB has several enhancements over the WATSUN space heating programs 1 Stratified tank model for short term or seasonal storage 2 Four possible heat pump locations 3 Inclusion of heat loss from the storage to the building outdoors or ground 4 Inclusion of heat loss from collector and storage piping to the building outdoors or ground The ENERPUB computer program gives detailed and accurate results for liquid based seasonal or short term storage provided that reasonable values for all system param
30. cessed SYSTEM Data CALFUN ECONAL NP PRINT2 Printer Printer HTPUMP ae LOGIC CLECTR STORG3 PIPE LOAD 60 xvi CALFUN subroutine that contains general form of heat pump power equation xvii LEAST subroutine to perform least squares analysis on heat pump power data points Four file definitions must be made before the program can be run Terminal Printer Unit 12 is the device for data input and program output Default Data Unit 10 is the file that contains default data for the system parameters Weather Data Unit 8 is the file that contains the TRNSYS compatible weather data The data must be written in the format 2 12 2 12 2 12 3 1 13 6 1 and contain month number day number hour number ground reflectivity ambient temperature C and solar radiation on a horizontal surface W m Processed Data Unit 9 is the file that is created by the program containing the solar radiation on the tilted surface and the ambient temperature 61 7 REFERENCES 1 Duffie and Beckman Solar Engineering of Thermal Processes John Wiley and Sons New York 1980 2 Orgill J F and Hollands K G T Solar Energy Vol 19 No 2 Correlation Equation for Hourly Diffuse Radiation on a Horizontal Surface 3 Temps R C and Coulson K L Solar Energy Vol 19 No 2 Solar Radiation Incident upon Slopes of Different Orientation 4 Klucher Solar Energy
31. cities that can be used by the program These cities are tabulated below solar radiation data as supplied by Atmospheric Environment Service is of two types derived or measured Measured data is as recorded by their monitoring equipment with missing data estimated from the previous day s values data is predicted by using other meteorological data such as rainfall cloud cover etc Latitude Solar Rad City Province Deg Year Derived Measured Victoria B C 48 7 1971 D Prince George B C 53 9 1974 Vancouver 49 2 1971 Summerland B C 49 6 1971 D 30 Frobisher Bay Resolute Edmonton Medicine Hat Uranium City Swift Current Saskatoon Churchill Brandon Winnipeg The Pas Thunder Bay Sault Ste Marie Sudbury Kapuskasing Kingston Muskoka Windsor London Toronto Ottawa Montreal Sept Iles Quebec Sherbrooke Riviere du Loop Bagotville Val D Or N W T N W T Alta Alta Sask Sask Sask Man Man Man Man Ont Ont Ont Ont Ont Ont Ont Ont Ont Ont Que Que Que Que Que Que Que 63 8 74 7 53 6 50 0 59 6 50 3 52 2 58 49 49 53 D 48 46 46 49 44 45 0 42 3 43 0 43 7 45 4 4 gt 45 5 50 2 46 8 45 4 47 8 48 3 48 0 1975 1971 1971 1971 1971 1971 1971 1975 1971 1971 1971 1971 1971 1971 1966 1971 1971 1971 1971 1971 1971 1971 1974
32. d temperature would need to be entered at the start of the program See Section 3 3 for typical ground temperatures TOP HEAT LOSS COEFF W C SIDE HEAT LOSS COEFF W C BOTTOM HEAT LOSS COEFF W C The top side and bottom heat loss coefficients for the storage tank respectively i e the surface area times the combined U value of the insulation and tank wall The R value of the ground does not have to be included if the ground temperatures in Section 3 3 are used OF STRATIFICATION TANK SEGMENTS The number of equal segments the tank should be split into for the purposes of modelling This parameter would equal 1 for a fully mixed tank For multiple tank storage or a tall slender tank this parameter should be greater than 1 maximum value is 6 See Figure l pg 3 SEG FOR COLLECTOR RETURN INTO TANK The segment number of the tank into which the collector fluid returns where segment number 1 is the top typically 1 SEG FOR BUILDING RETURN INTO TANK The segment number of the tank into which the building fluid returns typically the same value as parameter 26 29 Heat 25 MINIMUM ALLOWABLE STORAGE TEMPERATURE C The minimum allowable temperature of the storage tank water or oil for 011 tank heating The default value is 4 If the storage temperature drops below this value the program will print a warning and assumes an electric heater will bring the water up to the minimum temperature Pump P
33. e heat loss from the collector return piping and the fluid inlet temperature to the tank are calculated The next step is determination of the solar heat delivered to the load The temperature of the supply water to the building can be calculated knowing the temperature of the top of the storage tank and the temperature drop due to pipe heat loss The solar heat delivered to the water load is calculated by Ua 7 Tha ins 7 hot mains where e is the effectiveness of the heat exchanger T is the temperature of the top of the storage tank 51 is the temperature of the citymains water mains T is the hot water set point temperature hot If the solar heat can supply more heat than the building needs the fraction of the hour that the system must operate to meet the demand is calculated If the solar heating system cannot meet the demand the heat pump is used if available The energy output from the heat pump is calculated assuming that it operates for the full hour See Section 5 5 for a description of the heat pump algorithm If this value is greater than the heat load then the solar energy and heat pump energy are partioned so that they operate for the full hour and exactly meet the demand If the heat pump and solar heating system cannot meet the demand auxiliary energy is assumed to make up the difference If the solar heating system supplied heat to the building the heat loss from the return p
34. e radiation view factor from the collector to the sky with correction factors for non uniform distribution of diffuse radiation The correction factors for anisotropic diffuse radiation are taken from Temps and Coulson 3 and Klucher 4 The resulting equation is Hay eos s 1 sim s 2 1 F cos 60 sin 0 Hy where 1 49 reflected solar radiation on the tilted surface 15 _ 1 5 p p H where 4 the ground reflectivity The total solar radiation on the tilted surface Hz is the sum of the beam diffuse and reflected solar radiation components Hourly values of total solar radiation on a tilted surface ambient temperature day number and hour number are written to the scratch file When all the data has been processed and written to the scratch file the file is rewound to be ready for the system simulation 50 5 3 Algorithm for Calculation of Pipe Heat Loss The method of calculating pipe heat loss is the same for all of the pipes The heat loss is based on the difference between the average fluid temperature and the surrounding temperature UA T 1 pipe fm Tenv is the pipe heat loss coefficient Qtoss where UA ipe Ten is the temperature of the environment surrounding the pipe This is either a constant value hourly ambient temperature or monthly ground temperature depending on the value of parameters 61
35. equired to meet the space heating load not met by the solar heating system WATER LOAD GJ Energy required to meet the water heating load 37 AUX WATER GJ Auxiliary energy required to meet the water heating load The solar contribution to the water load is the difference between this value and the WATER LOAD PUMP POWER GJ Total energy consumed by all pumps and fans in the system including the heat pump The TOTAL ENERGY INPUT TO ELECTRIC RESISTANCE REFERENCE SYSTEM is the total energy demand of a non solar building If a fuel other than electricity is used this value should be divided by the seasonal furnace efficiency to determine the amount of fuel required The ENERGY SAVING is the reduction in energy achieved by adding the solar heating system i e percent solar The SEASONAL PERFORMANCE FACTOR is another measure of energy savings This factor is the number of times the non solar building auxiliary energy consumption exceeds the solar building auxiliary energy consumption The MAX HOURLY ENERGY INPUT MJ is the maximum hourly energy input of the solar building This value is useful for furnace sizing 4 2 Economic Analysis At the conclusion of the simulation year the economic analysis is calculated and printed The results of the economic analysis are extremely sensitive to the fuel excalation rate selected The first value of PRESENT WORTH is the total cost of installing and maintaining
36. eters are input 11 users should read and understand this manual before using the program 2 THE ENERPUB COMPUTER PROGRAM 2 1 System Configurations Figures 1 4 show the four possible space heating systems that can be simulated by the program The difference between these systems is the manner in which the heat is delivered to the space heating load Figure 5 shows the oil tank heating system Note that these systems are all liquid based the program cannot handle air based systems Piping heat losses can be considered for each of the four regions shown on the figures collector supply and return building supply and return The abbreviations used in the figures are CL solar collector ST thermal storage tank OIL 011 storage tank AUX auxiliary heating system DHW domestic hot water system HP heat pump HXc collector storage heat exchanger HX storage DHW heat exchanger storage building heat exchanger P1 P2 P3 P4 circulation pumps V1 V2 V3 V4 control valves 2000 piping heat loss regions 2 2 System Operating Strategies Space Heating The operating strategy for the four space heating systems can be broken into three distinct steps solar energy collection space heating and domestic hot water DHW heating Figure 1 Solar Heating System Schematic Heat Pump system type 0 Figure 2 Solar Heating System Schematic Heat Pump in Series with Solar
37. ficient that reduces collector solar transmission for incident angles off the normal according to theformula K 1 b 1 cose 1 The value for bo is obtainable from the collector data sheets and is usually negative If test results are not available use 0 10 for single glazed collectors and 0 175 for double glazed collectors COLLECTOR STORAGE HX EFFECTIVENESS The effectiveness of the heat exchanger between the collector and the storage must be between O and 1 For drainback systems this parameter is 1 0 Storage Parameters 20 21 STORAGE VOLUME COLLECTOR AREA 2 The ratio of storage volume to collector area typically 0 075 for short term storage and 5 0 for annual or seasonal storage The minimum storage size to ensure stability is approximately 0 04 m m STARTING TEMPERATURE C The starting temperature of the storage in degrees Celsius This parameter is important for short simulation periods and annual storage systems because of the large thermal mass relative to the energy collected typical value for Jan 1 is 20 24 22 23 24 25 26 27 28 SURROUNDING TEMPERATURE The temperature of the air surrounding the storage typically the building temperature for indoor storage For outdoor storage units use a value of 100 This signals to the program that the storage heat loss is to the ambient air For buried storage tanks use a value of 200 Note that monthly values of groun
38. iation to the extraterrestrial solar radiation If this ratio is low then the solar radiation must be mostly diffuse if this ratio is high the solar radiation must be mostly beam When the beam and diffuse solar radiation components are known standard geometric relations can be used to estimate the solar radiation components on a tilted surface When estimating solar radiation on a tilted surface a third component is introduced reflected radiation Reflected radiation can be estimated from the beam radiation and the ground albedo or reflectivity The program equations and execution procedure are given below At the start of each day the solar constant and the earth s solar declination are calculated The solar constant is given by 3e 7 4871 0 1 0 33 cos 2xN 365 in KJ hr m where N is the day number Jan 1 is 1 47 earth s declination is given by 6 23 45 2 284 N in radians 360 360 365 These values are assumed constant for each day All other calcu lations are made on an hourly basis The first step is to read the measured weather values from the data file For each hour the weather data file contains six values in the following order month number 1 12 day number 1 31 hour number 1 24 ground reflectivity solar radiation on a horizontal surface in Watts m ambient temperature in C an extraterrestrial solar
39. imulation will cover typically 365 or less but minimum period is approximately 7 days DAY 1 OF THE PERIOD 1 365 The first day of the simulation period January 1 is 1 September 1 is 244 etc If this parameter is changed on successive runs the weather data will automatically be reprocessed DETAILED PRINT OUT NO O YES 1 HR INTERVAL If this value is 0 monthly performance summaries will be printed If this value is greater than O hourly performance summaries will be printed every time period specified Thus if 6 were entered a performance summary will be printed every 6 hours for the 6th hour and not the total of the 6hr STARTING HOUR OF PRINT INTERVAL 0 1 The hour in which the detailed printing will start if parameter 4 is not O TILTED ANGLE OF COLLECTOR DEGREES The angle that the collector is tilted from the horizontal Range 0 to 90 If this parameter is changed on successive runs the weather data will automatically be reprocessed 22 7 COLLECTOR ORIENTATION SOUTH 0 DEGREES The number of degrees that the collector is oriented off due south east is positive west is negative Range 90 to 90 If this parameter is changed on successive runs the weather data will automatically be reprocessed Collector Parameters 10 GROSS COLLECTOR AREA M2 The gross collector area in square metres 11 MAXIMUM COLLECTOR OUTLET TEMP The maximum collector outlet temperature in degrees Celsius typical
40. ion rate r is rate of return on the best alternative investment The present worth of the loan repayments is L L J 1 1 1 r 1 where C s is the total cost of the solar system is the interest on the loan L is the loan period in years The salvage value is discounted back to present by N Thus the present worths of the solar investment with and without fuel costs are PW P solar SS m sal 57 solar 55 m f sal These are the values printed in the economic analysis The life cycle unit costs can be found from the present worth The life cycle unit cost is LUC solar Etot where Etot is the total heating load over the system life The solar life cycle unit cost is Fo SLUC P W solar where P is the fraction of the heating load met by the solar heating system 6 PROGRAM STRUCTURE The purpose of this section is to describe the program structure Only those individuals interested in modifying the program need read this section The program flow chart is shown in Figure 7 The program consists of a mainline and 16 subroutines i MAINLINE main program for file unit number allocation and calling of subroutines ii PRINT 1 subroutine to print title page at start of program PRINT 2 subroutine to print hourly energy analysis summaries i
41. iping is calculated The temperature of the load return water can be calculated knowing the pipe heat loss and heat delivered to the load 45 At the conclusion of the hour the new temperature s of the storage tank are calculated based on the collector and load flow rates Section 5 6 contains a detailed description of the stratified storage tank algorithm Finally the hourly heat flows are summed for the simulation period and the monthly and yearly totals displayed on the printer The economic analysis is performed at this point See Section 5 7 for a detailed description of the economic analysis algorithm 46 5 2 Algorithm to Process Weather Data Most Canadian weather stations measure only total solar radiation on a horizontal surface Most solar collectors however are tilted toward the sun to increase the incident solar radiation The program determines hourly values of total solar radiation beam diffuse and reflected on a tilted surface and stores the values in a scratch file The algorithm for converting horizontal solar radiation to tilted solar radiation is similar to the method used in Duffie and Beckman 1 In order to estimate the solar radiation on a tilted surface it is necessary to split the total measured horizontal solar radiation into its two components beam and diffuse It is possible to estimate the amount of diffuse solar radiation from the ratio of the measured solar rad
42. lar radiation contained in the weather data file See Section 5 2 for a detailed description of the algorithm When the processing of the weather data is completed the program begins the simulation A new value of solar radiation and ambient temperature is read for each hour simulated Based on the new values of ambient temperature the space heating load and the water heating load if necessary are calculated The space heating load is UAL Tyg 16 The next step is the calculation of the inlet fluid temperature to the collector This temperature is equal to the temperature at the bottom of the storage tank minus the temperature drop due to pipe heat loss between the storage and collector inlet See Section 5 3 for a detailed description of the algorithm for calculation of pipe heat 1055 Knowing the collector fluid inlet temperature 40 Figure 6 ENERPUB Flow Chart Start Read Default Data Modify Input Data Convert Data to Appropriate Units Is solar radiation on a tilted Burface available Initialize Parameters E Read solar radiation ambient temperature Calculate space and DHW loads Calculate collector supply pipe heat loss alcuTate collector inlet temperature Calculate collector performance Is collector heat gain positive N N Calculate solar radiation on a tilted surface Calculate collector return pipe heat loss
43. ly slightly below water boiling point 98 C For the 011 tank heating system this would be equal to the maximum allowable oil temperature 12 REQUIRED COL STORAGE TEMP DIFF C The required temperature difference between the bottom of the storage tank and the average collector temperature for the collector storage loop to operate 13 POWER OF PUMPS 1 AND 2 COLLECTOR AREA W M2 The pump power required to transfer solar heat from the collector to the Storage per unit collector area This parameter should include the power of pumps 1 and 2 For a closed loop system pump power is typically 10 W m 14 FLOW RATE HT CAPACITY W M2 C The flow rate times the heat capacity of the collector fluid per unit collector area This value is typically 55 W m C although the collector test value can be obtained from data sheets 15 FR TAU ALPHA ADJUSTED The of the collector as determined from certified performance testing 16 17 18 23 based gross collector area obtainable from data sheets If parameter 14 is not equal to the test flow rate the should be adjusted as given in Section 3 4 FR UL W M2 C ADJUSTED The of the collector as determined from certified performance testing based on gross collector area obtainable from data sheets If parameter 14 is not equal to the test flow rate the should be adjusted as given in Section 3 4 BO INCIDENT ANGLE MODIFIER Coef
44. ost mass flow rate kg hr mass flow rate through the collector kg hr mass of water in node i kg mass flow rate to the load kg hr day number of the year pump heat pump energy input KJ hr present worth of fuel expenditures present worth of maintenance expenditures present worth of salvage value present worth of solar investment present worth of loan repayments 5 auxiliary heat requirement KJ hr solar energy collected by collector KJ hr domestic hot water heating load heat transfer KJ hr heat storage nodes KJ hr heat pump energy output KJ hr space heating load KJ hr space heating load KJ hr 4 4 O fout hot mains Uu source lt ct 67 heat loss from pipe or tank KJ hr heat load not met by solar KJ hr solar contribution to DHW load KJ hr maximum possible solar contribution KJ hr heat transfer between storage nodes KJ hr rate of return node number where the collector fluid returns node number where the load fluid returns ratio of beam radiation on tilted surface to horizontal surface node number to which the collector return fluid is closest in temperature node number to which the load return fluid is closest in temperature solar life cycle unit cost ambient temperature 90 building temperature 9 collector stagnation temperature collector inlet tem
45. perature C collector outlet temperature temperature of the environment surrounding the pipe collector fluid inlet temperature C collector fluid outlet temperature 90 hot water set point temperature C city mains water temperature 90 temperature of the top of the storage tank C temperature of storage node i 90 heat pump source temperature storage temperature C 68 UA UA ipe UL building heat loss coefficient W C or KJ hr C pipe heat loss coefficient W C or KJ hr C collector heat loss coefficient W m C solar absorptivity azimuth angle 3 14159 density kg m stratified storage constant stratified storage constant stratified storage constant incident angle ENERPUB MANUAL ERRATA NOTICE The following corrections apply to the ENERPUB Users Manual November 1982 Page 42 Partion heat load should read Partition heat load Page 44 line 20 partioned should read partitioned Page 46 line 25 5 Should read SC Page 47 line 16 5 Should read SC Page 66 Qdown 7 the amount of heat transferred into the storage node when flow goes down Page 67 Qup the amount of heat transferred into the storage node when flow goes up Page 67 sc solar constant 849
46. r heating system lifetime typically 20 years TERM OF LOAN YEARS The number of years required to repay solar equipment loan INTEREST RATE OF LOAN 2 The percent interest rate on parameter 71 RATE OF RETURN DISCOUNT RATE The rate of return of best possible alternative investment in percent FIXED COST OF SOLAR COMP The fixed installed cost of solar components not including heat pump FIXED COST OF HP The fixed installed cost of heat pump YEARLY MAINTENANCE COST OF SOLAR COMP YR The yearly maintenance cost of solar components not including heat pump YEARLY MAINTENANCE COST OF HP YR The yearly maintenance cost of heat pump SALVAGE VALUE AT END OF PERIOD The salvage value of solar heating system at the end of the period specified in parameter 70 29 79 UNIT COST OF COLLECTOR 2 The installed cost of the system per square metre of collector not including the storage or the fixed costs of parameters 74 and 75 80 UNIT COST OF STORAGE M3 The installed cost of the storage unit per cubic metre of storage 81 UNIT COST OF FUEL AT PRESENT GJ The cost of fuel being displaced including seasonal efficiency of the auxiliary heater This value ranges from 5 to 15 depending on Tocation and fuel used 82 INFLATION RATE OF ENERGY 4 20 values of projected yearly increase in fuel cost in percent 3 2 Weather Data At present there is weather data for 46
47. ratures have been updated two checks are made the program The first check is for storage temperature instability If the temperature of a node is greater than the one above it it is assumed that density differences will cause perfect mixing of these nodes Because all the nodes have equal thermal capacity the new temperature of the nodes is the arith matic average of the mixing nodes The second check is on the minimum allowable temperature If the temperature of any of the nodes goes below the minimum allowable temperature it is assumed that an auxiliary heater comes on Because the heater is most probably placed in the bottom of the tank the heated water will rise and cause a fully mixed tank If the heater has to come on a warning flag is printed 56 5 7 Algorithm for Economic Analysis The algorithm for economic analysis is standard and is given in many economic textbooks Two economic indicators are calculated i present worth of solar savings with and without auxiliary energy ii life cycle unit cost of energy with and without solar heating system In the present worth analysis all future payments whether for fuel or bank loans are discounted back to present The present worth of yearly expenditures for fuel and maintenance are N AN N Ceue 1 1 r N N 6 er m j main are the first year costs for fuel and maintenance respectively Cruel Chain 1 is the fuel inflat
48. rculated through the building heat exchanger This heat exchanger may be either hot water radiators or a water to air heat exchanger placed in the furnace return air duct If the solar heat cannot meet the building demand the auxiliary heater will make up the difference 2 2 3 2 Space Heating Strategy system type 1 This system is similar to system type 0 except that a heat pump is added system first attempts to meet the heating demand from the solar heat valves 1 and 2 open valves 3 and 4 closed If the solar heat cannot meet the demand the solar heating system will not operate and the heat pump will attempt to meet the load using the storage tank as the heat source valves 3 and 4 open valves 1 and 2 closed the heat pump cannot meet the demand the auxiliary unit will make up the difference 2 2 3 3 Space Heating Strategy system type 2 This system operates in the same manner as system type 0 except that a heat pump is used as an auxiliary heater with the outside air as the heat source If the solar heat cannot meet the demand the heat pump will come on Note that unlike system type 1 the heat pump and the solar heat can supply heat to the building at the same time If the two heat sources cannot meet the heating demand the auxiliary unit will make up the difference 2 2 3 4 Space Heating Strategy system type 3 This system is similar to system type 1 except that solar heat cannot be delive
49. red directly to the heating load the solar heat is always transferred to the load by means of the heat pump This system will always have poorer performance than system type 1 however it has a simpler layout and control strategy 2 3 System Operating Strategies Oil Tank Heating This system differs from the previous four in that there is no space heating load The heating requirement is to keep the oil above a minimum temperature to prevent excessive viscosity so that it can be pumped out when necessary The control strategy for heat collection is as described in Section 2 2 There is heating in this system will be described in Section 3 1 10 input parameters be used to simulate draws of oi There is control strategy for space heating the collected heat is continually added to the tank 2 4 Tutorial Session This section describes the use of the ENERPUB computer program A full description of the input parameters is given in Section 3 and program output is described in Section 4 When you have successfully signed on to your account and accessed the program the computer will respond with the header e e e e Xo Ge EES KE G ENERPUB 1 PROGRAM VERSION 1 2 ENERMODAL ENGINEERING LIMITED JULY 1982 REE EEE e EE ERE KR RE EERE HERE EEE DEVELOPED BY ENERMODAL ENGINEERING LIMITED 421 KING STRE
50. si Teg 7 4 m C5 p 01 05 Qup miC where Tea is the temperature of the node i at the beginning of the hour Te is the temperature of the node i at the end of the hour are the hourly mass flows from the collector and load to the storage mes mp is the specific heat of water mi is the mass of the water in node i 91 05 7 the amount of heat lost to the environment by conduction out the storage walls Q f own is the amount of heat transferred into the node by flow up coming up or going down 54 are control functions that define the 5 where the fluid effectively returns The control functions are given by if r siss or 5 sisr 17 54 1 otherwise 0 if s 1 5 3L sis rL then 1 jr 5 1 otherwise 0 where 15 the node number where the collector fluid returns n is the node number where the load fluid returns S is the node number to which the collector return fluid is closest in temperature is the node number to which the load return fluid is closest in temperature SL The quantity Q is given by down for 9 0 75421 7 194 1 1 4 N where mC E 5 otherwise dawn 0 The quantity is given by for 1 lt 0 Qup TSi 7 7514 up 55 After the tempe
51. temperatures If the evaporator temperature is outside this range the internal control system will prevent the heat pump from operating To simulate this operation the program checks at the beginning of the hour to see if the source tem perature is between the minimum and maximum values it is outside of this range it is assumed that the heat pump does not supply any heat for that hour 53 5 6 Algorithm for Stratified Storage Tank Water storage tanks in solar systems will exhibit some temperature stratification The magnitude of the stratification depends on system flow rates and temperatures The model used in the program is as mended by Klein 6 This model is similar to yet more flexible than the model given in Duffie and Beckman 1 The tank is modelled as a series of horizontal nodes A mass energy balance is performed on the nodes for each simulated hour The water entering the tank from either the load or the collector is assumed to rise or fall to the node closest in temperature If water is flowing from the load and the collector the fluid streams are assumed fully mixed before they enter each segment The energy balance on the tank also takes into account the heat lost by each node to the environment and the heat transferred from the storage top node to the domestic hot water by means of the DHW heat exchanger A heat balance on a storage node gives T T me si
52. v INPUT interactive subroutine for user input of data and printing of input data This subroutine reads the default data from a data file i V WEATH subroutine for converting measured horizontal solar radiation to the tilted surface The weather data is read from a data file and the processed data is written to a new file vi SYSTEM subroutine to initialize system parameters and sum the system energy flows At the conclusion of the simulation the yearly results are printed vii LOGIC subroutine to call the component subroutines depending energy flows viii CLECTR subroutine to calculate collector performance ix LOAD subroutine to calculate water and building heat loads and the solar contribution to these loads x HTPUMP subroutine to calculate heat pump performance xi PIPE cree Mr to calculate heat loss from a pipe used for all four pipes xii STORG3 subroutine to calculate the new temperature s of the storage tank at the end of the hour xiii ECONAL subroutine to perform economic analysis xiv TGRD subroutine to determine monthly ground temperature HPCOEF subroutine to determine heat pump power input and output characteristics 59 Figure 7 ENERPUB Program Structure Default Data File Output to Printer Input from Terminal INPUT MAINLINE PRINT 1 LEAST Pro
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