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

a)
`Tb=1845.05K`

b)
`Q=1000.25KJ`

c)
`\mu=0.59`

Step-by-step 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

`(Tb)/(Tx)=(Ty)/(Ta)`

`Tb=(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-(Ta)/(Tx)`

`\mu=1-(298)/(723)`

`\mu=0.59`