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(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

Sagot :

Answer:

a)  [tex]Tb=1845.05K[/tex]

b)  [tex]Q=1000.25KJ[/tex]

c)  [tex]\mu=0.59[/tex]

Explanation:

From the question we are told that:

Temperature x [tex]Tx=450c=>723K[/tex]

Pressure x [tex]Px=2.5MPa[/tex]

Temperature y [tex]Ty=600c=>873K[/tex]

Pressure y [tex]Py=0.45MPa[/tex]

Let

Air atmospheric temperature be [tex]25c[/tex]

Therefore

Temperature [tex]Ta=25+273=298k[/tex]

Generally the equation for Otto cycle is mathematically given by

 [tex]\frac{Tb}{Tx}=\frac{Ty}{Ta}[/tex]

 [tex]Tb=\frac{873*723}{298}[/tex]

 [tex]Tb=2118.05[/tex]

Therefore the peak cycle temperature (°C)

 [tex]Tb=2118.05k[/tex]

 [tex]Tb=2118.05-273[/tex]

 [tex]Tb=1845.05K[/tex]

Generally the equation for Heat addition is mathematically given by

 [tex]Q=Cv(Tb-Tx)[/tex]

 [tex]Q=Cv(2118.05-723)[/tex]

 [tex]Q=1000.25KJ[/tex]

Generally the equation for Thermal  efficiency is mathematically given by

 [tex]\mu=1-\frac{Ta}{Tx}[/tex]

 [tex]\mu=1-\frac{298}{723}[/tex]

 [tex]\mu=0.59[/tex]