Question

(8 pts.) Air in an Otto cycle engine is compressed to a temperature and pressure of 450 °C and 2.5 MPa. After the power stroke, the conditions are 600 °C and 0.45 MPa. Find the peak cycle temperature (°C), heat addition (kJ/kg), and efficiency

Answer 1

Answer:

a)  $Tb=1845.05K$

b)  $Q=1000.25KJ$

c)  $\mu=0.59$

Explanation:

From the question we are told that:

Temperature x $Tx=450c=>723K$

Pressure x $Px=2.5MPa$

Temperature y $Ty=600c=>873K$

Pressure y $Py=0.45MPa$

Let

Air atmospheric temperature be $25c$

Therefore

Temperature $Ta=25+273=298k$

Generally the equation for Otto cycle is mathematically given by

 $\frac{Tb}{Tx}=\frac{Ty}{Ta}$

 $Tb=\frac{873*723}{298}$

 $Tb=2118.05$

Therefore the peak cycle temperature (°C)

 $Tb=2118.05k$

 $Tb=2118.05-273$

 $Tb=1845.05K$

Generally the equation for Heat addition is mathematically given by

 $Q=Cv(Tb-Tx)$

 $Q=Cv(2118.05-723)$

 $Q=1000.25KJ$

Generally the equation for Thermal  efficiency is mathematically given by

 $\mu=1-\frac{Ta}{Tx}$

 $\mu=1-\frac{298}{723}$

 $\mu=0.59$