
#1
Apr613, 03:25 PM

P: 1

I have a 4stroke,4 cylinder, 2.0 litre engine at a speed of 2850 rpm, the engine works in stoichiometric conditions and the mass of fuel injected per cycle per cylinder is 18 mg. The temperature and pressure at the start of compression 44 °C and 1 bar, respectively. The engine compression ratio is 10.3:1, I need to find the:
a)Work transfer between cylinder gas and moving piston during the compression stroke, in Joule b)Temperature at the end of combustion (in Kelvin), taking the energy content of the natural gas fuel as 34 MJ/kg c)Assuming a thermal efficiency of 28%, determine the engine power output at the above operating conditions (in kW) I also have the Cv=0.7, γ=1.35 and A/F=14.4 I first found P2, and then I found T2 then I found the W12. To find the Qin I used the following equation Qin = Qcomb= ηc*mfuel*QLHV where I put QLHV= 34MJ/kg, Combustion efficiency ηc=0.95 and mfuel=18mg. Then i found T3 and T4. And then i used this equation to find the power output W=Wnet*N/n Where Wnet= QinQout , n=2 for 4stroke engine , N=2850/60. I always get the wrong results tho, do you have any idea where I'm wrong. 


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