Assignment3 - Assignment 3 Automotive Powertrains Gabriel...

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Assignment 3 Automotive Powertrains Gabriel Alcantara 100384537 . Prof. Greg Rohrauer March 22, 2010

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%{ 5-2. Two engine options are to be offered in a new automobile model. Engine A is naturally aspirated with a compression ratio of 10.5:1 and cylinder inlet conditions of 60C and 96 kPa. Engine B is supercharged with aftercooling and has cylinder inlet conditions of 80C and 130 kPa. To avoid knock problems, it is desirable to have the air-fuel temperature at the start of combustion in engine B to be the same as in engine A. %} k=1.35; a)Temperature at start of combustion in engine A [C] % Engine A: rc=10.5; %kJ/kg T1=60+273.15 %K P1=96; %kpa P2=P1*(rc)^1.35; %kPa T2s=T1*(P2/P1)^((k-1)/k)-273.15 %C T2s = 485.5255 b) Compression ratio of engine B which would give the same temperature at the start of combustion. % Engine B: T1B=80+273.15; %K P1B=130; %kPa P2B=((T2s+273.15)/(T1B))^(k/(k-1))*P1B; rcB=(P2B/P1B)^(1/k) %T2s=T1*(rcB)^(k-1)-273.15 %T2s=T1*(P2/P1)^((k-1)/k)% 1
rcB = 8.8889 (c) Temperature reduction in the aftercooler of engine B if the compressor has an isentropic efficiency of 82% and inlet conditions are the same as in engine A. [C] ns=0.82; T2A=T1-ns*(T1-(T2s+273.15)); decrease=T2s-(T2A-273.15) decrease = 76.5946 2

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5-3. Air enters the intake manifold at 74F and 14.7 psia on a V12 airplane engine with throttle body injection, using gasoline at an equivalence ratio of = 0.95. It can be assumed that all the fuel evaporates in the adiabatic manifold.
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