Answer to Question #116959 in Mechanical Engineering for Curtis

Question #116959
A single cylinder petrol engine has a volume compression ratio of 4:1, takes in a mixture of fuel and air at a temperature of 20°Cand its pressure is 101kPa. If the pressure at the end of the compression stroke is 1.5MPa what will be its final temperature?
Expert's answer

The problem involves an adiabatic compression, therefore the governing equation will be 

"\\frac{V_2}{V_1}=\\frac{1}{4}" "P_1=101kPa=0.101\\times{10}^6 Pa\nT_1=20 C = 293.15 K\nP_2=1.5 MPa=1.5\\times{10}^6Pa"

"P*V^k = constant"

and also, "T* V^{k-1} = constant"

Considering two states, using the first equation:

"0.101\\times{10}^6\\times4^k=1.5\\times{10}^6\\times1\n=>4^k=14.81=>\\ k\\cong\\ 1.944\\"

Now it’s possible to use the second equation 

"T_1\\times{V_1}^{k-1}=T_2\\times{V_2}^{k-1}\n\\\\\n293.15\\times4^{0.944}=T_2\\Rightarrow\n\\\\T_2=1085.01\\ K\\ =811.86\\ C"

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Assignment Expert
05.06.20, 15:47

Dear Curtis, Questions in this section are answered for free. We can't fulfill them all and there is no guarantee of answering certain question but we are doing our best. And if answer is published it means it was attentively checked by experts. You can try it yourself by publishing your question. Although if you have serious assignment that requires large amount of work and hence cannot be done for free you can submit it as assignment and our experts will surely assist you.

20.05.20, 11:58

A compressed air storage cylinder has a volume of 0.5m^3 and contains air at an absolute pressure of 1.8MPa and temperature 20°C. A quantity of the air is released during which the temperature of the remaining air falls to 15°C and the pressure to 1.5MPa. Calculate the mass of the air released. The characteristic gas constant for air is 287Jkg−1K^−1.

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