PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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3.2.3 Control strategies for the plantThe control philosophy used to control the micro-trigeneration system during thesimulations was based on matching the thermal demand. Each individual componentwithin the system therefore responded to thermal based controls. In ESP-r a plant canbe controlled by creating a dedicated control scheme. Table 3.5 describes thecontrols used on the plant system components feeding the 3 household buildingmodel.Table 3.5 - Control scheme used to control the plant in the 3 household buildingControl Loop 1DescriptionTime – basedcontrol schemeControl Loop 2DescriptionTime – basedcontrol schemeControl Loop 3DescriptionTime – basedcontrol schemeControl Loop 4DescriptionTime – basedcontrol schemeControl Loop 5CHP controlControl scheme used to control (actuate) CHP. Control is based on feedbackreceived from temperature sensor sensing the temperature of the water return tothe hot water storage tank.00.00-10.00 Hours 65°C / 75°C ‘On’/‘Off’ Control with 10ºC dead band10.00-14.00 Hours 40°C / 50°C ‘On’/‘Off’ Control with 10ºC dead band14.00-24.00 Hours 65°C / 75°C ‘On’/‘Off’ Control with 10ºC dead bandAuxiliary boiler controlControl scheme used to control (actuate) auxiliary boiler. Control is based onfeedback received from temperature sensor sensing the temperature of the waterflowing through hot water pump 1.00.00-10.00 Hours 60°C / 65°C ‘On’/‘Off’ Control with 5ºC dead band10.00-15.00 Hours - Boiler ‘Off’15.00-24.00 Hours 60°C / 65°C ‘On’/‘Off’ Control with 5ºC dead bandBypass valve calorifier controlControl scheme used to control the amount of hot water passing through orbypassing calorifier. Based on a proportional control which senses thetemperature of the water flowing through the DHW supply pump the valvevaries between fully open (F.O) and fully closed (F.C.).00.00-24.00 HoursChillerFully Open 65°CFully Closed 60°CProportional ControlControl scheme used to control (actuate) chiller. Control is based on feedbackreceived from temperature sensor sensing the temperature of the water returnfrom the cooling coils.00.00-10.00 Hours 12°C / 6°C ‘On’/‘Off’ Control with 6ºC dead band10.00-15.00 Hours - Chiller ‘Off’15.00-24.00 Hours 12°C / 6°C ‘On’/‘Off’ Control with 6ºC dead bandDHW pumpDescription Responds to external file created using DWH profile modelled in Chapter 2100
Control Loop 6DescriptionTime – basedcontrol schemeBypass valve cooling coil 1 controlControl scheme used to control the amount of chilled water passing through orbypassing cooling coil 1. Based on a proportional control which senses thetemperature of the air return from the ground floor apartment the valve variesbetween fully open (F.O) and fully closed (F.C.).00.00-08.00 Hours Valve varies between fully open and fully closed whenair temperature varies between 24ºC-21ºC respectively.08.00-18.00 Hours No control18.00-24.00 Hours Valve varies between fully open and fully closed whenair temperature varies between 24ºC-21ºC respectively.Controls 1 to 4 are used to ensure that the system works within user definedspecifications. Sensors and actuators were all positioned within the plant system;sensing a parameter within a part of the plant network and sending feedback to anactuator in another part of the plant. For example, control loop 1 operates the CHPunit via an ‘On’/‘Off’ control strategy featuring a 10ºC ‘dead band’ which ensuredthat the contents within the hot water storage tank were continuously within acontrolled 10°C temperature range. Set back control is employed during theafternoon (between 10.00 and 14.00 Hours) when demand is low. In parallel theauxiliary boiler was controlled (using loop 2) in such a way that if a shortfall in thesupply hot water temperature was detected, the boiler would switch ‘On’ tosupplement the heating energy provided by the CHP Unit.In addition to mimicking the classical control seen in buildings and systems, controlin building simulation can also be used for more abstract purposes. Control loop 5 forexample was used to mimic the draw on the hot water tank using one-minute profilesgenerated using the approach described in Chapter 2. In this case the controller setsthe flow from the tank (modelled using a pump) to be equal to the flow rate in theprofile (refer to Figures 2.38 and 2.39).Finally loop 6 is an example of a control loop which creates an interaction between aplant system component and the building. In this case the sensor is positioned in theexhaust duct of the ground floor apartment, sensing the return air temperature fromthe ground floor apartment and sending feedback to the bypass valve of the coolingcoil. Based on the temperature sensed, the bypass valve of the cooling coil increases101
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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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Page 78 and 79: Table 2.7 - Scaling factors for the
Page 80 and 81: NVF values for washing machines, el
Page 82 and 83: Table 2.10 - Annual electrical ener
Page 84 and 85: 2.4.4 Creating the profiles used in
Page 86 and 87: Fig. 2.16 - Electrical demand profi
Page 88 and 89: Fig. 2.19 - High efficiency electri
Page 90 and 91: 2.4.4.3 6 Household buildingAs ment
Page 92 and 93: 2.29 and Figure 2.30 show the resul
Page 94 and 95: period [11].In order to improve on
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Page 98 and 99: similar fashion to the modelling of
Page 100 and 101: observed measurements from a number
Page 102 and 103: Fig. 2.37 - Total internal heat gai
Page 104 and 105: comparing water consumption related
Page 106 and 107: various aspects which make up the h
Page 108 and 109: natural Resources" - (LN 238 of 200
Page 110 and 111: in Domestic Appliances and Lighting
Page 112 and 113: [49] DEFRA (2010). "Dishwashers Gov
Page 114 and 115: CHAPTER 3MODELLINGMICRO-TRIGENERATI
Page 116 and 117: the same research also suggests tha
Page 118 and 119: cooling device in conjunction with
Page 120 and 121: simulation tool ESP-r by explaining
Page 122 and 123: Fig 3.2 - Basic micro-trigeneration
Page 126 and 127: or decrease the flow rate of the co
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Page 132 and 133: coefficients for the future and pre
Page 134 and 135: Applying basic energy and mass cons
Page 136 and 137: CH Power , the chiller’s refriger
Page 138 and 139: general form of equation (3.16) [33
Page 140 and 141: functions of hot water circuit inle
Page 142 and 143: circuit were obtained and how the p
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Page 148 and 149: the model was then compared to a se
Page 150 and 151: Fig. 3.9 - Modelled chilled water c
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Page 154 and 155: The selected tank size is based on
Page 156 and 157: 3.5 Summary of Chapter 3This chapte
Page 158 and 159: Conservation in Buildings and Commu
Page 160 and 161: uilding simulation." Doctoral Thesi
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 (
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4.2.1.3 Calculating the fuel consum
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cogeneration technologies [16].- (4
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the present 1.088 kgCO 2 per kWh de
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Table 4.4 - Explanation of the cash
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FIT and considering the cost involv
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impact they have on the energetic,
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Conservation in Buildings and Commu
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CHAPTER 5RESULTSANDDISCUSSIONThis c
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increases so does energy-efficiency
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the building fabric is most effecti
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Instances where the load duration c
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households, GF refers to the ground
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Finally, and this will be the discu
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In the table, the low and high effi
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The scenario with the lowest number
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Comparing Figure 5.3 and 5.4, respe
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number of cycles during the cooling
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5.3.3 Chiller’s performanceAs dis
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5.3.4 Electrical performance of the
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decrease in net imports and net dem
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Table 5.10 - Micro-trigeneration sy
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trigeneration system primary energy
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Table 5.11 - Micro-trigeneration pr
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The PES obtained for the different
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Difference inprimary energybetween
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Similar results are obtained for al
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2 High/High efficiency3 High/Curren
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Fig. 5.8 - Sensitivity of Emissions
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Similarly to the effect on PE SEPAR
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5.5 Micro-trigeneration system econ
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As electricity costs increase (rela
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ii.In the latter case the magnitude
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Resultingdifference incash flowDiff
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Multiple of current electricity tar
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of the system diminishes with incre
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Fig. 5.17 - CF and CF component ter
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shows that exporting all the cogene
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LPG price level when the micro-trig
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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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