To produce work a gas is expanded adiabatically from 3 MPa and 300oC to 80 kPa in a piston-cylinder device. Which of these two choices –air with an isentropic expansion efficiency of 90% or neon with an isentropic expansion efficiency of 80% – will produce the most work?

Explanation:

Check attachment for solution

Given that, .

The initial gas pressure is

P1 = 3 MPa

The initial gas temperature

T1 = 300°C

The final gas pressure is

P2 = 80 KPa

Which are of two choices

1. Air with an isentropic expansion of 90% efficiency

2. Neon with an isentropic expansion of 80% efficiency

We want to know which will produce more work

object 2 because all the other ones are wrong