PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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educed by 4% per 500 metres, and by 6% above 3000 metres. Therefore, if the altitude is above the threshold level, and if the engine is situated in an area where it is affected by ambient temperature, the maximum available power (rated power) must be reduced accordingly. If the engine is situated in an area that is not affected by ambient temperature, the constant average room temperature is used for derating. The algorithm used to determine the rated power used for the rest of the procedure is shown in Figure 5.6. No No No Is alt > H1 ? Is derating required ? PC = 0 Are 2 heights given ? PC = ((Alt - H1) / D1) x H1PC No Rat ed Power = Rat ed Power No Is one height given ? Yes Yes Yes Yes Is Temp Given ? Yes Is plant sited in area affected by ambient temp ? Yes Is Ambient > Temp ? No Does PC = 0 ? Figure 5.6 Derating Algorithm Yes Is alt > H2 ? No Is alt > H1 ? Yes No Alt = Altitude Ambient = Ambient Temperature Room = Room Temperature No DERATING CRITERIA Above H1 metres above sea level: H1PC % per D1 metres Above H2 metres above sea level: H2PC % per D2 metres Above Temp Degrees C: TempPC % per Deg Degrees C 126 Yes Yes No Pated Power = Rated Power - (( Rated Power x PC ) / 100) PC = (((Alt - H2) / D2) x H2PC) + ((H2 - H1) / D1) x H1PC PC = ((Alt - H1) / D1) x H1PC PC = PC + ((Room - Temp) / Deg) x TempPC PC = PC + ((Ambient - Temp) / Deg) x TempPC
5.2.3 Engine Performance in the Context of Varying Load In order to define the performance of an engine, it is necessary to know the required percentage loading, and its efficiency or fuel consumption at that load. If CHP is to be considered, the ratio of heat to electricity output must also be known. 5.7 shows a representative heat balance curve for a diesel engine, though exact characteristics vary with engine size and configuration. It can be seen that the percentage of fuel energy input which contributes to net work (mechanical work, and hence electricity production) remains fairly constant down to around 70% of full load, but then starts to decrease rapidly, showing that the efficiency of electricity production decreases with percentage load (i.e. more fuel is required per kWh of electricity produced at lower percentage loadings). At the same time, the amount of heat lost to the jacket coolant water and exhaust gases, from which heat recovery is possible for CHP generation, increases due to this decreased efficiency. It can also be seen from Figure 5.7 that, if the percentage fuel energy input values for net work, exhaust and jacket water are summed at different percentage loadings, the overall percentage of fuel energy input which contributes to these three outputs remains fairly constant. Values below 20% loading have not been taken into consideration here as this is typically recommended by manufacturers to be the minimum load value to avoid damage to the engine. This means that the overall efficiency (for electricity and heat) of a typical engine CHP generation system remains fairly constant, while the fuel to electrical efficiency decreases with decreased load. Therefore, more heat is produced at lower loads, keeping the overall percentage of recoverable energy (electricity and heat) fairly constant. Using this assumption, it is possible to estimate the ratio of heat to electricity production at any percentage loading, provided the ratio is known for 100% loading. These figures are typical for both diesel engines and ICEs, with the overall efficiency (heat and electricity) generally being around 90% of the fuel input. 127
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Decision Support for New and Renewa
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Abstract The global requirement for
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CONTENTS 1 ENERGY SYSTEMS FOR SUSTA
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5.5 Steam Turbine Model 149 5.6 Fue
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FIGURES Figure 1.1 Final Energy Con
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Figure 7.30 Following Electricity a
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on the use of fossil fuels, energy
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The general increase in energy cons
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supply is reduced or eliminated, lo
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Figure 1.3 The Electricity Supply G
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on different generation mixes depen
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Various studies have been carried o
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provision for smaller areas, and he
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1.7 References [1] The Internationa
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2 Options for New and Renewable Ene
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the amount of usable heat that is g
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the conversion of petrol cars; howe
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set times, producing a constant ele
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partial load. Fast response and sta
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2.3 The Production and Storage of H
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dedicated boiler, which runs contin
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Figure 2.3 A Typical Hydrogen Filli
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part of the natural carbon cycle (a
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Figure 2.4 Layout of a Gasification
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met by process integration and the
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Figure 2.5 The Inputs and Outputs o
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1. Scale for measuring out lye and
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feedstock being used. Sugary feedst
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carbon dioxide via steam reforming.
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• Where CHP is used, the balance
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[22] Vehicle Certification Agency (
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[55] M. A. Paisley, J. M. Irving, R
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3 Approaches to Renewable Energy Sy
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Because of the intermittent nature
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A renewable energy supply evaluatio
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the system are kept. The output of
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There are various models available
Page 75 and 76: When the use of climate dependant i
Page 77 and 78: 3.5 References [1] M. Muselli, G. N
Page 79 and 80: 4 A Procedure for Demand and Supply
Page 81 and 82: pumped storage and flywheels), a ba
Page 83 and 84: for the agricultural vehicle use re
Page 85 and 86: Figure 4.4 Combining Demands to Tak
Page 87 and 88: ates for vehicles, engines and othe
Page 89 and 90: Figure 4.5 Derived Fuel Production
Page 91 and 92: together if desired, and taken forw
Page 93 and 94: profiles are output from this part
Page 95 and 96: dividing the production rate at eac
Page 97 and 98: As it would be too confusing to sho
Page 99 and 100: Figure 4.12 Output of the Matching
Page 101 and 102: However, when more than one transpo
Page 103 and 104: considered, this amount is added to
Page 105 and 106: users are alerted if there is not e
Page 107 and 108: at the matching stage, along with t
Page 109 and 110: vehicles if they are increased by 1
Page 111 and 112: If biogas is being considered, the
Page 113 and 114: The number of timesteps per hour wi
Page 115 and 116: After the algorithm has been follow
Page 117 and 118: • Float Charge - once the battery
Page 119 and 120: Discharge No tank = tank fuel used
Page 121 and 122: equired (kW) = maxkWh x bulk% (5.16
Page 123 and 124: An example of the output graph prod
Page 125: 5.2.1 Required Power Specifically d
Page 129 and 130: used for gas powered ICEs, but the
Page 131 and 132: and five times, depending on the nu
Page 133 and 134: Is PL < Min ? No Is PL = 0 ? No Is
Page 135 and 136: where Max = maximum energy availabl
Page 137 and 138: where Ratiopart = heat to electrici
Page 139 and 140: (including following heat demand wh
Page 141 and 142: where SFC = specific fuel consumpti
Page 143 and 144: engines running respectively). If t
Page 145 and 146: (continued) Is Fuel Available > (4
Page 147 and 148: of the definition window for a Stir
Page 149 and 150: and continuous operation. Again, mu
Page 151 and 152: The performance of a fuel cell is n
Page 153 and 154: percentage loading, rather than usi
Page 155 and 156: Is Min = 0 ? No Is Min = PC1 ? No I
Page 157 and 158: 5.6.4 If Fuel Availability is Less
Page 159 and 160: 5.7 Electrolyser Model An electroly
Page 161 and 162: original calculation of the amount
Page 163 and 164: 5.8 Regenerative Fuel Cell Model A
Page 165 and 166: following the heat demand. To follo
Page 167 and 168: C:\ My Documents\ Nic\ Thesis\ Old\
Page 169 and 170: As 1 kWh = 3610.3 kJ, and using lit
Page 171 and 172: Add Heat to Water Storage Tank Usin
Page 173 and 174: Use Stored Hot Water to Supply Heat
Page 175 and 176: information is given about the over
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[23] K. Foger, B. Godfrey, “Syste
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the gasification and pyrolysis defi
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eing used each day for a continuous
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Where Biogas = Biogas production ra
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6.1.3 Use of Biogas Various options
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The amount of hydrogen that can be
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direct proportion, and the weight o
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produce in total (Nm 3 per tonne fe
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Electricity (kW) = Elec x Feed (6.1
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3. Make hydrogen via steam reformin
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Where Methane = Methane Production
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(continued) Keep as medium heating
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Yes Feed1 = Yield1 x Land1 / No. of
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production and energy use profiles
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If it is the last timestep of the p
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For each process, the process chara
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At the end of the simulation, graph
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As the time required for one batch
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Ethanol = Factor1 x Eth x Timesteps
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6.5 Electrolysis As it is sometimes
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6.7 Landfill Gas Processing As the
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Demand Profile Design & Profile Dat
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Figure 7.2 Degree-Days Versus Month
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Stage 1 - Sustainable Fuel Supply S
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The different profile of use graphs
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Figure 7.3 Fermentation System Inpu
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Figure 7.7 Fermentation System Info
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Figure 7.10 Fermentation System Out
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The output obtained when a second h
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Figure 7.16 Anaerobic Digestion Par
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Figure 7.19 Fermentation System Inp
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clarity. A constant supply rate of
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Figure 7.25 Heat Demand Profile Fig
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Figure 7.28 Effect of Minimum Load
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esidual heat demand as this would r
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Figure 7.35 Second Engine: Followin
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This chapter described how the over
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heat and electricity during the tou
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Figure 8.2: Overall Yearly Heat Dem
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to allow for efficient operation du
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would be incurred, and the scale of
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Figure 8.5: Electricity Supply and
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heat demand or both, or run at cons
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ut with 30% less land being require
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9 Conclusions and Recommendations T
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through these, technically viable p
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considered. The introduction of coo
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When considering larger geographica
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Appendix 1: Program Windows Figure
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Figure A1.5 CreateClimate.exe Figur
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Figure A1.9: Demand Profile Designe
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Figure A1.13: Derived Fuel Supply W
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Figure A1.17: Fermentation System D
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Figure A1.21: PV Electrolysis Syste
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Figure A1.25: Fuel Supply Profile D
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Figure A1.29: Auxilliary Supply Def
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Figure A1.33: Stirling Engine Syste
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Figure A1.37: Fuel Cell System Defi
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Figure A1.41: Electric Vehicle Syst
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Figure A1.45: Vehicle Conversion Fa
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Figure A1.49: Heating System Defini
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Figure A1.53: Pumped Hydro System D
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Figure A1.57: Auto Search Evaluatio
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PhD Thesis - Energy Systems Research Unit - University of Strathclyde

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