7431 KB - Fachhochschule Köln
Contents
1. I T i 260 300 340 380 Temperature K of Mixture of Glycol 20 whe 35 52 Figure 5 Densities in kg m of Glycol at different tempera tures in K and percentage of solution with Water The differ ent levels of solution are 20 35 and 52 of Glycol with water Warmenetz the density kg m relation to temperature K of the solution Water Glycol at different percentages of Glycol whereas Figure 6 shows the Specific Heat kJ kg K in relation to temperature K of the dif ferent percentage solutions of Glycol in Water Table Dd 21 from VDI Warmeatlas Sun amp Teja 2003 These plots will be used to convert the measured volumetric flow to heat flow rate on the system 3 755 Hea IC f 3 50 7 Spec 3 25 4 3 00 i 260 300 340 380 Temperature K of Mixture of Glycol 20 whe 35 E 52 Figure 6 Specific Heats kJ kg K of Glycol at different tem peratures in K and percentage of solution with Water The different levels of solution are 20 35 and 52 of Glycol with water To use the relation of densities and heat from Fig ures 5 and 6 a linear model of this data must be built and since the system uses only 20 mixture of Glycol and 80 of water the red lines with dots from the figures are selected for the proposed re gression models 1040 oe eo 1030 se gt a p 1020 R Pees hk Q se 1010 ee e2. metabolon Measuring Flow and Temperature on the heating network Ramos R t Rojas F t Becerril J A 1 Rebolledo M t Gonzalez A 1 Fachhochschule K ln Campus Gummersbach Institut fur Automation amp Industrial IT Steinmullerallee 1 51643 Gummersbach Abstract This paper presents a series of flow and tempera ture measurements on the principal heat network of metabolon in Lindlar Germany These measure ments intend to show the behaviour of the system on specific production areas of metabolon for fu ture monitoring and optimisation purposes Such measurements allow the analysis of the system s heat flow through the network which showed that losses exist some areas The results demonstrate successfully that the temperature and flow chang es deserve more detailed and fixed monitoring in specific areas to help the user decide the optimum measuring point 6 Introduction Nowadays heating networks are a very important source of heat transfer in communities Different mediums are used to produce this heat with differ ent efficiency levels During the transfer process ambient temperature and humidity may cause no table losses on the system The following paper focuses on providing the re sults of a series of temperature and volumetric flow measurements on a heating network using two modern mobile ultrasonic devices made in one week with a weekend included in the middle during the beginning of the cold season
3. 1000 ea Q 7 i i en E 275 300 325 350 375 Temperature K Figure 7 Linear model for the density properties p in kg m of a mixture of 20 Glycol and 80 of water with an accu racy of 99 994 represented in Figure 5 The dots are the real values and the dashed line represents the linear model 69 Warmenetz 4 00 5 a 3 95 7 ial Specific Heat e 3 90 o T T T T T 275 300 325 350 375 Temperature K Figure 8 Linear model for the specific heat properties c in kJ kg K of a mixture of 20 Glycol and 80 of water with an accuracy of 99 999 represented in Figure 6 The dots are the real values and the dashed line represents the linear model 4 1 Volumetric to heat flow rate Since the obtained measurements were tempera ture and volumetric flow to obtain heat flow rate a conversion is needed using the heat flow relation Cengel Y A amp Boles M A oe 1 c x AT x Ap Where q is the volumetric flow in a Q is the heat flow rate in kW c is the specific heat capacity in iz and p the density in Notice that equation 1 is in m for the measurements are in I thus to convert to the International System of Units the relation l 1 m 2 h 1000 h can be used to obtain the desired volumetric flow From 1 it is obtained heat flow rate in 5i for 1 is equal to 1 kW thus Gat iy 3 h 3600 is used to obtain heat flow rate in kW To use the dens
4. 3 wa gt ni h e A A N SIA Altk rper M 1a ae DA 2 Da dee 67 Warmenetz Point number 5 CHP was selected because it is the main source of heat on the system Be cause metabolon site is not flat the different heights cause some losses on the system thus the other four points were selected because of its dis tribution of heights on the system Figure 2 shows as well the selected measuring points for this task represented by the flowmeter symbol in a circle Two flowmeter were selected so the system can be measured from heat source CHPs to the other areas shown in Figure 2 For this reason one flow meter flow meter 1 Shall always measure the CHP s to use it as a refer ence point The other areas shall be measured with flow meter 2 in tacts of 30 minutes approxi mately During nights and the available weekend flow meter 2 stayed at the Old Workshop to measure the behaviour of the system on the initial day of the week Monday 10 12 2012 3 1 Considerations on the different areas The weather conditions at the time of the meas urements play an important role on the use of the heating network which defines if the system was being used or not Figure 4 shows the hourly aver age behaviour of the temperatures during the peri od of the measurements Old Workshop In the old workshop the measurements took place in the basement of the building where the main heating network is connected to the child
5. before Before the heat exchanger that connects the CHP s and the main heating net work an approximate total volume of medium on the line of 5 000 is considered and after the heat exchanger a total volume of 26 000 I Considerations for the measurements Since the measurements shall be done on different areas ultrasonic flow meters need some infor mation before the measurement could be done Table 1 shows the pipe properties for each meas ured area taken in consideration for the configura tion of the flow meters Since the pipes were al most new a roughness of 1 mm and no lining was considered for every pipe place on the first floor The system is almost new and has a simple flow control system Table 1 Pipe configuration for every area Used to configure the mobile sensors Area Out Diam mm Wall Thick mm CHP 108 00 2 00 Old Workshop 89 00 2 00 TCSW 42 00 1 50 New Workshop 42 00 1 00 Wood drying 76 00 2 00 4 Heating medium On the previous section it was mentioned that the heating network contains a mixture of Water H20 and Mono ethylene Glycol C2H4 OH 2 This mix ture depends on the freezing point which is need ed for the system to support lowest temperatures For this reason it is determined that an approxi mate mixture of 80 Water and 20 Glycol was being used during the time of the measurements to support temperatures of 10 C Figure 5 shows 1110 4 1080 4 1050 4 Density 1020
6. in Germa ny The results shall provide an overview of the 65 Warmenetz heat demand and losses on the system to intro duce various fixed measuring instruments for mon itoring and preventive purposes First a brief introduction to the metabolon site is presented to the reader where the different areas of the site the heating network and the medium used to transfer the heat on the whole system are introduced The measurements will be described on section 3 with a detailed explanation of the schedule and different areas being measured Linked to section 2 in section 4 the physical prop erties of the medium used to transfer the heat trough the pipes on the network is explained with the presentation of two linear models to obtain more accurate results when converting from volu metric to heat flow Section 5 will focus on the flow meters used for these measurements the ultrasonic technology behind them and the installation requirements to perform better measurements To finish the paper Section 6 presents the plots of the performed measurements during the specified time period with a brief discussion 2 metabolon site Located almost 43 km to the east of Cologne in Lindlar Germany Before 2004 metabolon was used as a garbage and waste deposit for the sur rounding cities Figure 1 shows a map with the lo cation of metabolon site Today it is still used as a garbage collection plant to process it and produce compost f
7. 2 2012 12 12 2012 and the j et peer or ae YW a ew a 2s 0 j aoe Sozialcontainer X a m m ane Sy _ lager ST A s V aign etungan intan n oan ex 4 f me gt y 4 Deponieabschnitt ae Rew Leponioabechnil Wi DA 6 1 BSH SS A I Aa A 1 it Logistik X h N Sy m m eee a a n o sr if a Figure 3 Details of the main areas of metabolon site 6 Ww YW J emer we gt Ferraro eee m m eee sal a Deponieabschnitt DA 3 Warmenetz Heat Source CHP CHP Composte and Fermenting Plant Pump station 00 00 l Legend D Measurement Point Main Heating Network Secundary Heating Network Figure 2 Organisational chart of the heating network at metabolon There are two different mediums used on the net work to transfer the heat First there is Water H20 as principal medium and second there is a mixture of different percentages of Monoethylene Glycol C H OH 2 whose mixture depends on the outside temperatures The mixture available on the system during the measurements was around 80 Water and 20 Glycol proposed areas to observe were 1 Old workshop Transfer centre for special wastes TCSW Wood drying system New workshop Combined heat and power plant CHP a a dA f I Ae eee a som RS Sortieranlage 1 o m boi ee L ror ANAA N RHB
8. e and finally received by the sec ond transducer It is important to mention that the signals are emitted alternatively and against the flow direction As the medium in which the signals propagate is flowing their transit time in flow di rection is shorter than against the flow direction Figure 10b FLEXIM GmbH User Manual The difference between transit times At is meas ured allowing to determine the average flow veloc ity on the propagation path of the ultrasonic sig nals FLEXIM GmbH User Manual A flow profile correction is then performed to obtain the area average of the flow velocity which is proportional to the volumetric flow rate In the Fluxus the volu metric flow rate is calculated by V ke Ak 2 11 2t Where V is the volumetric flow ke is the fluid me chanics calibration factor A the cross sectional pipe area k acoustical calibration factor At transit time difference and t transit time in the medium The setting up of all the parameters needs for mak ing the measurements are simplified in a quick star up guide that is provided with the sensor or also available on line 6 Results The following section will show the measurements taken from the period mentioned in Section 3 For space reasons and demonstration purposes only those who presented a special behaviour and measures during the weekend are going to be shown Combined heat and power plant CHP Figure 12 shows the complete set of measu
9. ecay slowly At this period of time this behaviour is shown in the whole system which origin comes from the heat source Warmenetz Supply Temp 80 Return Temp 75 qeras 70 Temperature C 65 60 12 00 12 04 12 08 12 12 12 16 12 20 12 24 12 28 Time min a Supply dashed line and Return solid line temperatures C of the Wood drying system 10 7 10 5 Vol Flow m h 10 4 10 3 12 00 12 04 12 08 12 12 12 16 12 20 12 24 12 28 Time min b Volumetric Flow of the Wood drying system 160 140 120 Heat Flow Rate kW 80 60 40 12 00 12 04 12 08 12 12 12 16 12 20 12 24 12 28 Time min c Heat Flow kW of the Wood drying system Figure 11 The plots show the measurements made at the Wood drying system in the time window from 11 59 to 12 29 clock 10 12 2012 From top to bottom the first plot shows the Supply and Return temperatures in C the second plot shows the volumetric flow in and the third plot shows the heat flow rate in kilowatt 73 Warmenetz New workshop Figure 15 show the measurements taken at the New workshop on Tuesday 11 12 2012 from 11 49 to 12 20 clock It can be said that at that time window there was a stable temperature ten dency of the system but the volumetric flow changes almost 0 6 7 Discussion Combined heat and power plant CHP The measurements on the CHP s showed that the temperature on
10. ermodynam ics An engineering approach McGraw Hill Higher Education Boston 6 edition Cengel Y A amp Boles M A 2009 Termodinamica McGraw Hill Mexico etc 6 edition op 2009 FLEXIM GmbH User Manual UMFLUXUS F6V40EN 2010 Lipt k B G 2012 Instrument engineers hand book CRC Press Boca Raton and FL 4 edition 2003 2012 metabolon online metabolon Site 2013 http www metabolon de metabolon Sun T amp Teja A 2003 Density viscosity and termal conductivity of aqueous ethylene diethy lene and triethylene glycol mixtures between 290 k and 450 k Journal of Chemical amp Engineering Data 48 1 198 202 VDI Warmeatlas 2006 Springer Berlin Heidel berg and New York 10 edition
11. es C of the Old workshop Saturday 08 12 00 Sunday 09 12 00 Monday 10 Time hr b Volumetric Flow of the Old workshop 150 100 50 Saturday 08 12 00 Sunday 09 12 00 Monday 10 Time hr c Heat Flow kW of the Old workshop Figure 13 The plots show the measurements made at the Old workshop at Basement in the time window from 07 12 2012 to 10 12 2012 where the major ticks mark the start of a day 00 00 hours the minor ticks are separated by one hour and the middle ticks represent the noon 12 00 hours of the corresponding day From top to bottom the first plot shows the Supply and Return temperature in C the second plot shows the volumetric flow in m and the last the heat flow rate in kilowatt kW 76 Supply Temp 65 Return Temp 60 O o 55 ab E 5 50 kK 45 40 11 03 11 07 11 11 11 15 11 19 11 23 11 27 11 31 11 35 Time min a Supply dashed line and Return solid line temperatures C of the of the Transfer centre for special wastes Vol Flow m h 0 9 0 8 TEOS 11 07 Tis THS Tise 11 23 Vises Pies 11 39 Time min b Volumetric Flow of the Transfer centre for special wastes 16 lt F 15 a FE gt LL 14 E 13 TEOS 1107 AI TEW TEIS T123 1127 TL1 Tiss Time min c Heat Flow kW of the Transfer centre for special wastes Figure 14 Measurements at the Transfer centre for s
12. g for the ultrasonic energy to go from trans ducer A to transducer B is given by the expression L 7 ae Go cos and the time tga to go from B to A is given by L tas 8 C V cos where C is the speed of sound in the medium L the acoustic path length in the medium is the angle of the path with respect to the pipe axis By combining terms and simplifying it can be shown that for V C At t tap a 9 Also giving us A A V L coso k 2 A 10 where ty is the average transit time between the transducers Since the cross sectional area of the pipe section is known the product of area and ve locity will yield volumetric flow rate 5 2 Installation cares The correct selection of the measuring point is cru cial for getting reliable measurements results and a high measurement accuracy A measurement on a pipe is possible if the ultrasound propagates with sufficient high amplitude acoustic penetration the flow profile is fully developed undisturbed flow profile which will be discussed on para graphs acoustic penetration and undisturbed flow profile The correct selection of the measuring point and the correct positioning of the transducers is influ enced by x Diameter material lining wall thickness and form of the pipe the medium and gas bubbles in the medium Avoid measuring points in the vicinity of defor mations and defects of the pipe and in the
13. g system was turned off The pe culiar observation for this system is that neither the supply temperature nor the flow changed much since the system is coupled with a hydraulic separator The system could be optimised by in stalling a valve to open or close whenever the dry ing system is running or not respectively This will avoid the main system to loose heat during these shut offs for once it restarts the system shall re gain the lost heat to obtain the desired tempera ture Transfer centre for special wastes Since the transfer centre for special wastes is locat ed on the highest point in metabolon it is some times difficult for the system to reach such point and besides that the use of an expansion tank to protect the system from high pressures does not allow sometimes the medium to reach there Be cause the temperature differences vary between 0 C and 40 C and since the higher the tempera ture difference the higher the pressure on the line the small expansion tank avoids that this high pressures the medium to reach the sub system at this point A higher expansion tank can help avoid this problem but further investigation shall be done to avoid the wrong expansion tank New workshop The new workshop did not presented any special characteristics since it is shown that a flow control is managing the fluctuations of the system keeping the temperatures stable Warmenetz 90 i i i i oO 80 arat
14. ities and specific heats at different tempera tures from the relations of Figure 5 and Figure 6 for the mixture of 20 Glycol red lines and circle points their respective linear model have to be obtained as 70 p 0 3771955 xT 1139 086 4 c 0 001525496 x T 3 45154 5 Both linear models are represented in Figure 7 and Figure 8 Once the respective conversions and line ar models are obtained equations 2 and 3 are sub stituted in equation 1 to get the final conversion to heat flow rate from volumetric flow _ qxc x AT xp 6 3600000 5 Equipment The measuring devices used for the task are two mobile ultrasonic flow meters with temperature option To understand in detail how these devices are used to measure an overview to the basic idea of the ultrasonic technology and the cares one must consider on the installation of the devices to achieve an accurate measurement is introduced 5 1 Ultrasonic theory There are two main types of ultrasonic flow me ters Transit time and Doppler reflection Transit time flow meters are designed for clean fluids and Doppler reflection type for dirty slurry type streams The sensor that was used in this arti cle is a transit time flow meter Transit time flow meters A transit time flow meter measures flow by meas uring the time taken for an ultrasonic energy pulse to traverse a pipe section both with and against the flow of the liquid within the pipe 2 6 The time ta
15. ive quick ultrasonic flow measure ment with clamp on technology for all type of pip ing The Fluxus has an integrated data logger with a serial interface and a Li lon battery that provides 14 hours of measurement operation The Fluxus F601 can work in outsides and in a lot of environ ments thus its water and dust tight IP65 re sistant against oil many liquids and dirt Figure 9 FLEXIM GmbH User Manual Sometimes the gas eous or solid content in the medium increase oc casionally during measurement a measurement 71 Warmenetz with the transit time difference principle is no longer possible Noise Trek is a feature integrated in this sensor that will be selected by the flow me ter This measurement method allows the flow meter to achieve a stable measurement even with high gaseous or solid content FLEXIM GmbH User Manual FLUXUS FOOT eee FLEXIM Figure 9 Front and connections views of the Flow meter Fluxus F601 used for the measurements a Path of ultrasonic signal ty T b Transit time difference At Figure 10 Representation of the ultrasonic path and the transit time 72 The Fluxus sensor measures the flow of the medi um by ultrasonic signals using the transit time difference method as measurement principle A pipe line has two transducers installed one in front of another Figure 10 a transducer emits sig nals that 1 2 3 4 5 6 7 8 t are reflected to the opposite sid
16. ja i seers 2 eof i i an e i o 70 t i apot gt 3 3 60 Q E 50 N i i Return Temp 30 i i i i 12 00 Saturday 08 12 00 Sunday 09 12 00 Monday 10 12 00 Tuesday 11 Time hr a Supply dashed line and Return solid line temperatures C of the CHP s 34 32 lt E 30 28 LL 3 26 24 22 12 00 Saturday 08 12 00 Sunday 09 12 00 Monday 10 12 00 Tuesday 11 Time hr b Volumetric Flow of the CHP s 60 1 a 400 gt a 200 0 12 00 Saturday 08 12 00 Sunday 09 12 00 Monday 10 12 00 Tuesday 11 Time hr c Heat Flow kW of the CHP s Figure 12 The plots show the measurements made at the CHP s in the time window from 07 12 2012 to 11 12 2012 where the major ticks mark the start of a day 00 00 hours the minor ticks are separated by one hour and the middle ticks represent the noon 12 00 hours of the corresponding day From top to bottom the first plot shows the Supply and Return temperature in C the second plot shows the volumetric flow in and the last the heat flow rate in kilowatt kW 13 Warmenetz Vol Flow m h Temperature C Heat Flow Rate kW 80 Sys dappele a montare gy q o atann a a Oy hed ei 70 60 50 40 3 7 Supply Temp i Return Temp Saturday 08 12 00 Sunday 09 12 00 Monday 10 Time hr a Supply dashed line and Return solid line temperatur
17. network through a heat exchanger In this case it is im portant to mention that the system on this area is equipped with a special weather temperature con trol which is being used to control the supply flow on the child network by using weather infor mation Transfer Centre for special wastes In the transfer centre for special wastes the meas urements took place at the roof of the building This area is the highest point in the whole heating 68 network It is well known that sometimes it pre sents problems with the heating system because of the height and installation of the system The sys tem consist in a heat exchanger with an small ex pansion tank which is being used to protect the heating water system from high pressures on the main stream Temperature C T T T T T T T Fri Sat Sun Mon Tue Wed Thu Fri 07 08 09 10 11 12 13 Date Figure 4 Hourly averaged temperatures in C at metabolon during the measurements from Friday 7 to Friday 14 of De cember 2012 Wood drying system At the wood chips drying system the measure ments took place outside This system is coupled with an hydraulic separator to join the main and the child network systems which maintains a con stant low pressure and avoids variability Combined heat and power plant At the CHP s the measurements took place at the beginning of the main heating network after the main heat exchanger This is the main heat source as mentioned
18. or the farmers of the region Taking ad vantage of the site s location metabolon is used as a research facility to improve and develop the waste to energy process as well as to introduce the area as a family park to the surrounding com munities and show them the necessities ad vantages of recycling and management of waste This will play an important role on future genera tions for it will mean that more investment and interest on research and development will improve the process 66 e Lindlar A metabolon Bergheim Oberbergischer Kreis K ln Rhein Erft Kreis Rhein Sieg Kreis Bonn Figure 1 Location of metabolon site represented by the orange triangle metabolon consists in different areas as follows listed in english and german Transfer centre Transferzentrum Office building Verwaltungsgeb ude Research building Forschungsgeb ude Old workshop Alte Werkstatt Sorting plant Sortieranlage SE Sa i Fermenting and Composting Plant Vergarungs und Kompostierungsanlage VKL Sanitation Hygienisierung 8 Transfer centre for special wastes TCSW Sonderabfall Zwischenlager 9 Wood drying system at the Biomass farm Holztrocknung beim Biomassehof 10 New workshop Neue Werkstatt 11 Combined heat and power plant CHP Blockheizkraftwerk BHKW The items from 1 through 3 are offices and build ings used for administrative purposes The rest are working areas for the differen
19. pecial wastes in the time window from from 10 12 2012 11 03 to 10 12 2012 11 35 From top to bottom the first plot shows the Sup ply and Return temperature in C the second plot shows the volu metric flow in m and the last the heat flow rate in kilowatt kW Warmenetz 80 78 76 O 74 5 w si 72 ab H 70 68 66 11 50 11 54 11 58 12 02 12 06 12 10 12 14 12 18 Time min a Supply dashed line and Return solid line temperatures C of the of the New Workshop 5 3 5 2 E 5 1 5 50 iL 2 4 9 4 8 4 7 11 50 11 54 11 58 12 02 12 06 12 10 12 14 12 18 Time min b Volumetric Flow of the New Workshop 29 28 feb w oc B amp B g LL 5 als 26 25 11 50 11 54 11 58 12 02 12 06 12 10 12 14 12 18 Time min c Heat Flow kW of the New Workshop Figure 15 Measurements at the New Workshop in the time win dow from from 11 12 2012 11 49 to 11 12 2012 12 20 From top to bottom the first plot shows the Supply and Return temperature in C the second plot shows the volumetric flow in and the last the heat flow rate in kilowatt kW 77 Warmenetz 8 Conclusions The use of ultrasonic mobile sensors is an ad vantage to analyse these kind of systems at differ ent points and times where it is only useful for short term analysis 1 week and not for long term measurements The measurements presented in this paper should help take the decision
20. re ments from 07 12 2012 11 12 2012 11 17 time gathered from the CHP s A common pattern be tween the volumetric flow Figure 12b and the supply temperature Figure 12a can be observed Notice that at around 02 00 o clock on Sunday morning 09 12 2012 the supply temperature reaches at some points the same value as the re turn temperature Old workshop Figures 13a and 13c show the measurements of the Old workshop in the time window from 07 12 2012 15 24 to 10 12 2012 9 22 o clock in the morning Notice from Figure 13a that the same be haviour of the supply and return temperatures is shown as in Figure 12a at the same time 02 00 o clock on Sunday morning 12 12 2012 but Figure 13b shows a different tendency than the one shown in Figure 12b where instead of showing a decreasing flow related with the temperature be haviour it increases Wood drying system Figure 11 shows the measurements taken at the Wood drying system on Monday 10 12 2012 from 11 59 to 12 29 clock where at around 12 09 o clock the heat flow rate went down almost 100kW because the return temperature rose to almost 73 C reaching almost the supply tempera ture of 77 C Transfer centre for special wastes In Figure 14 are the measurements shown which we have taken at the Transfer centre for special wastes on Monday 10 12 2012 from 11 03 to 11 35 clock Notice that during this small period of time the flow and the temperatures d
21. t processes of the metabolon site 2 1 Sample and inoculum preparation About 2 kg of 95 air dried SG produced from the non alcoholic fermentation of a mixture The main source of heat comes from the CHP plant provided by a third supplier where metabolon pays a monthly yearly fee for their energy consumption There are three CHP s available on the system which depending on the heat demand they are started as needed Each CHP provides the network with 600 kW of heat making a total of 1800 kW when all of the three are working Because the net work size is too long the heating system itself en counters some troubles supplying enough heat to the buildings enlisted from 1 to 4 Thus a second ary network which source is located in the base ment of the alte Werkstatt has been installed to supply the requirements of these areas This sec ondary network is supplied by an oven that burns wood chips to produce heat which in combination with a heat exchanger is then used to heat water Figure 2 shows the organisational chart of the heating network in metabolon where the main network is represented by the continuous line purple and the secondary connections by the dashed line orange 3 Measurements Using 2 loaned mobile ultrasonic meters intro duced in Section 5 to measure the system first a limited amount of areas were selected to obtain the most information of the system The measure ments took place 07 1
22. the supply side reached some times the temperature on the return side Considering that the supply volume is around 5 000 and that on the main network a volume of 26 000 is flowing through the system when the flow decreased the supply temperature decreased as well followed by the return temperature on a delay of 2 hours which is to be expected because of the volume difference More volume takes long er to reach the same temperature of the mediums as less volume The reason for such flow decays comes from the seasonal tendency of the system i e the work schedule and lunch times causing the system to pressure and lower the flow Notice as well that by observing the heat flow the system sometimes had no heat transfer at all and that around 07 00 o clock in the morning the system reached again an optimum operating point Old workshop The old workshop has a control system based on the weather conditions which controls flow The measurements show that indeed to maintain the temperature the flow reacted as it should without any problems From the weather conditions shown in Figure 4 it is noticed that on the exact same time periods where the temperatures decreased an inverted tendency of flow is shown in Figure 13b this is because of the flow control system based on the weather conditions 74 Wood drying system The wood chips drying system showed a very sim ple behaviour when the return temperature in creased the dryin
23. to install fixed temperature and flow meters to calculate the heat consumption of the most important areas The results showed a general representation of the behaviour of the system during different periods of time It was observed that sometimes at specific areas the system consumed more energy than oth er times where the measurements showed that the return temperatures reached at certain hours of the day the supply temperatures and giving heat losses to it Sometimes they also showed that the supply temperatures decreased to the same level of the return temperature where it was discussed that this fluctuation was caused by the heat trans fer of two bodies with different masses It is expected from this case study research that for future investments these measurements can help provide the user some reference of the be haviour of the system during several hours of the day and particular areas and that the installation of an historical database for the already installed fixed flow meters with temperature options will benefit to optimize the heat losses of the system and provide reporting solutions to maintain a cross reference with the monthly yearly bill of the CHP s supplier 78 Referenzen R C Baker R C 2000 Flow measurement hand book Industrial designs operating principles per formance and applications Cambridge University Press Cambridge and UK and New York and USA Cengel Y A amp Boles M A 2008 Th
24. vicinity of welds This is because near deformations the liquid can became turbulent and therefore gener ate bubbles Also avoid locations with deposit for mation in the pipe FLEXIM GmbH User Manual Acoustic penetration The acoustic penetration is reached when pipe and medium do not attenuate the sound signal so Warmenetz strongly that it is completely absorbed before reaching the second transducer The attenuation in the pipe and in the medium depends on kinematic viscosity of the medium proportion of gas bubbles and solids medium deposits on the inner pipe wall and pipe material The following requirements must be fulfilled at the measuring point the pipe is always filled completely no material deposits in the pipe and no bubbles accumulate Undisturbed flow profile Some flow elements elbows slide valves valves control valves pumps reducers diffusers etc distort the flow profile in their vicinity A careful selection of the measuring point helps to reduce the impact of disturbance sources It is important that the measuring point is chosen at a sufficient distance from any disturbance sources Only then it can be assumed that the flow profile in the pipe is fully developed However measuring results can be obtained even if the recommended disturbance sources cannot be observed for practical reasons 5 3 The Equipment The Fluxus F601 sensor is a portable instrument for non invas
Download Pdf Manuals
Related Search