PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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The scenario with the lowest number of operating hours was Scenario 4 High , whichincludes an additional flat plate solar water heater to the basic plant configuration.The solar energy absorbed by the SWH offsets part of the heating energy supplywhich otherwise needs to be provided by the CHP. This results in a reduction in boththe number of operating hours and fuel consumption. Although the effect wasmarginal (to reduce the increase in temperature across the SWH and prevent anydamage being caused to the CHP unit the SWH selected was a small sized collectormore suitable for a single family rather than a multi-family building), the resultsshow the potential effect of adding other sources of distributed energy in the system.5.3.1.2 Cycling ‘On’/‘Off’When assessing the effect of different operating conditions on micro-trigenerationsystem performance, an important operational aspect which is often overlooked, isthe CHP unit ‘On’/‘Off’ cycling. Prime-movers especially those involving movingmechanical parts such as the internal combustion engine used in this case, havedetermined start-up and cooling down times. A constant high number of switchingcycles is not ideal as the wear of the various components is accelerated. Table 5.6,tabulates the calculated seasonal and annual daily average number of ‘On’/‘Off’cycles together with the total seasonal and annual number of cycles for the differentscenarios investigated. Operational behaviour is unaffected by the appliances’electrical efficiency. Effect of improving building fabricThe first part of the analysis focuses on the effect improving the building fabric hason the CHP unit ‘On’/‘Off’ cycling. For both Scenarios 1 and 2, improving thebuilding fabric results in an increase in the number of cycles during the heatingseason, and a decrease in a number of cycles during the cooling season.To explain this result, recall that the CHP unit was controlled by an ‘On’/‘Off’controller with a 10°C dead band which switched the CHP unit ‘On’ below a lowerlimit of 65°C, and switched the unit ‘Off’ whenever the temperature surpassed theupper limit of 75°C.178
Table 5.6 - CHP Unit switching cyclesScenarioBuilding fabricScenario descriptionDaily average CHP unit cyclingShoulder/Heating/Cooling/Annual(No. of ‘On’/‘Off’ cycles per day)Total CHP unit ‘On’/‘Off’ cyclingShoulder/Heating/Cooling/Annual(Total No. of cycles)1 Low1 High3 Household building with low efficiency building fabric; Basic plantconfiguration (0.3m 3 hot water tank)3 Household building with high efficiency building fabric; Basic plantconfiguration (0.3m 3 hot water tank)7 / 11 / 20 / 12 1,057 / 1,037 / 2,461 / 4,5547 / 12 / 19 / 12 1,057 / 1,059 / 2,358 / 4,474Percentage difference between 1 Low and 1 High (%) 0.0 / 2.1 / -4.2 / -1.82 Low2 High6 Household building with low efficiency building fabric; Basic plantconfiguration (0.5m 3 hot water tank)6 Household building with high efficiency building fabric; Basic plantconfiguration (0.5m 3 hot water tank)8 / 8 / 19 / 12 1,208 / 792 / 2,268 / 4,2688 / 10 / 18 / 12 1,208 / 893 / 2,204 / 4,304Percentage difference between 2 Low and 2 High (%) 0.0 / 12.7 / -2.8 / 0.93 High6 Household building with high efficiency building fabric; Basic plantconfiguration and (0.5m 3 hot water tank) with additional 0.3m 3 chilled water tank8 / 10 / 14 / 10 1,208 / 893 / 1,732 / 3,833Percentage difference between 2 High and 3 High (%) 0.0 / 0.0 / -21.4 / -10.94 High6 Household building with high efficiency building fabric; Basic plantconfiguration (0.5m 3 hot water tank) with additional 2.5m 2 flat plate SWH7 / 9 / 18 / 11 1,064 / 825 / 2,130 / 4,019Percentage difference between 2 High and 4 High (%) -11.9 / -7.6 / -3.4 / -6.65 High6 Household building with high efficiency building fabric; Basic plantconfiguration (0.5m 3 hot water tank). All electricity is exported8 / 10 / 18 / 12 1,208 / 893 / 2,204 / 4,304Percentage difference between 2 High and 5 High (%) 0.0 / 0.0 / 0.0 / 0.0179
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University of StrathclydeDepartment
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ACKNOWLEDGEMENTSIt has been a long
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ABSTRACTThe domestic sector account
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TABLE OF CONTENTSACKNOWLEDGEMENTSAB
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2.4.3.3 Aggregated loads frequency
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4.1.1.1 Factoring for electricity g
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5.5.1.2 Present worth assuming a va
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LIST OF FIGURESFig. 1.1 Separate ge
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Fig. 2.38 Aggregated DHW draw profi
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Fig. 5.23 PP for Scenarios 1 and 2
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uilding 95Table 3.5 Control scheme
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ACRONYMS & ABBREVATIONSBMS Building
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CHAPTER 1INTRODUCTIONChapter overvi
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uildings, and Directive 2006/32/EC
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Micro-cogeneration can make use of
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offer reasonable and adequate retur
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system in a residential building, i
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conditions have on the performance
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effective manner. The research in t
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investigate how a residential micro
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Table 1.1 also includes additional
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1.7 Chapter References[1] DG for En
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[18] Pehnt, M., Cames, M., Fischer,
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[39] Cardona, E. and Piacentino, A.
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[56] Shin, Y., Seo, J.A., Cho, H.C,
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2.1 Modelling residential demand -
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minute resolution data. The researc
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2.3.1 Example: specifying the build
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Table 2.1 - Dimensions of the model
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In this second enlarged building, t
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Table 2.3 - Main characteristics of
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Table 2.4 - Main characteristics of
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esolution demand data for individua
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the original data (see equation 2.1
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the course of a year. The end resul
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specific appliance at a particular
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consumption during this period is e
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awarded on a random basis following
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Table 2.7 - Scaling factors for the
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NVF values for washing machines, el
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Table 2.10 - Annual electrical ener
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2.4.4 Creating the profiles used in
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Fig. 2.16 - Electrical demand profi
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Fig. 2.19 - High efficiency electri
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2.4.4.3 6 Household buildingAs ment
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2.29 and Figure 2.30 show the resul
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period [11].In order to improve on
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(as discussed by Richardson et al.
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similar fashion to the modelling of
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observed measurements from a number
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Fig. 2.37 - Total internal heat gai
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comparing water consumption related
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various aspects which make up the h
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natural Resources" - (LN 238 of 200
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in Domestic Appliances and Lighting
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[49] DEFRA (2010). "Dishwashers Gov
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CHAPTER 3MODELLINGMICRO-TRIGENERATI
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the same research also suggests tha
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cooling device in conjunction with
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simulation tool ESP-r by explaining
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Fig 3.2 - Basic micro-trigeneration
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3.2.3 Control strategies for the pl
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or decrease the flow rate of the co
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efrigerant, which in this case is w
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arbitrary cycle configuration, usin
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coefficients for the future and pre
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Applying basic energy and mass cons
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CH Power , the chiller’s refriger
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general form of equation (3.16) [33
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functions of hot water circuit inle
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circuit were obtained and how the p
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the internal high and low pressures
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the imaginary boundary constituting
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the model was then compared to a se
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Fig. 3.9 - Modelled chilled water c
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Page 156 and 157: 3.5 Summary of Chapter 3This chapte
Page 158 and 159: Conservation in Buildings and Commu
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Page 162 and 163: CHAPTER 4SIMULATIONMETHODOLOGYANDAN
Page 164 and 165: Table 4.1 - Scenarios investigatedS
Page 166 and 167: The building fabric, building size
Page 168 and 169: analysis in the case of the interme
Page 170 and 171: micro-trigeneration system are thos
Page 172 and 173: profile for that same time period (
Page 174 and 175: 4.2.1.3 Calculating the fuel consum
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Page 178 and 179: the present 1.088 kgCO 2 per kWh de
Page 180 and 181: Table 4.4 - Explanation of the cash
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Page 186 and 187: Conservation in Buildings and Commu
Page 188 and 189: CHAPTER 5RESULTSANDDISCUSSIONThis c
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Page 194 and 195: Instances where the load duration c
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Page 198 and 199: Finally, and this will be the discu
Page 200 and 201: In the table, the low and high effi
Page 204 and 205: Comparing Figure 5.3 and 5.4, respe
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Page 208 and 209: 5.3.3 Chiller’s performanceAs dis
Page 210 and 211: 5.3.4 Electrical performance of the
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Page 214 and 215: Table 5.10 - Micro-trigeneration sy
Page 216 and 217: trigeneration system primary energy
Page 218 and 219: Table 5.11 - Micro-trigeneration pr
Page 220 and 221: The PES obtained for the different
Page 222 and 223: Difference inprimary energybetween
Page 224 and 225: Similar results are obtained for al
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Page 228 and 229: Fig. 5.8 - Sensitivity of Emissions
Page 230 and 231: Similarly to the effect on PE SEPAR
Page 232 and 233: 5.5 Micro-trigeneration system econ
Page 234 and 235: As electricity costs increase (rela
Page 236 and 237: ii.In the latter case the magnitude
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Page 240 and 241: Multiple of current electricity tar
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Page 244 and 245: Fig. 5.17 - CF and CF component ter
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Page 250 and 251: Minimum threshold viability of the
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Similarly to the PW and the IRR, it
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Table 5.13 - Summary of micro-trige
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performance of the micro-trigenerat
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directly affect the system’s ener
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micro-trigeneration system. Convers
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CHAPTER 6CONCLUSION:OUTCOMESANDFUTU
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and power demands of the building.
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circuits associated with the absorp
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the subject. More work therefore ne
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plant models using the building sim
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APPENDIX AEquation factors for sele
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Factors for use in equation (2.1) f
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APPENDIX BElectrical demand profile
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Fig. B4 - Current efficiency electr
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Fig. B10 - High efficiency electric
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Fig. B16 - Current efficiency elect
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Component ESP-r Database: Annex 42
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0.0000 #88 Performance map: Thermal
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99.999 #1 Evaporator Total Mass (Fl
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100.00 #13 Boiling temperature of f
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One way to solve a partial differen
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The ‘self coupling term’ is def
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C ******************** CMP73C *****
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&COMMON/PCOND/CONVAR(MPCON,MCONVR),
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C and the inlet point into the solu
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IF(CSVF(INOD1,1).LE.BDATA(IPCOMP,17
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C Calculate T1 (DegC): T1 = ((T16-T
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XST=4010 DST=-(9.133128) + (0.94396
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& + 2500.559)*1000C Refrigerating p
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End IfC Calculate h3 (J/kg): h3=h2+
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&&ElseEnd IfActPow=0ActPow = PCONDR
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C Node 1, thermal mass effected by
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WRITE(ITU,*) ' Connection(s) ',ICON
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Fig. F.1 - IRR for scenarios with d
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Fig. F.5 - PP for scenarios with di
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PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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