Question

Helium gas expands from 20 psia, 600 R and 9 ft3 to 15 psia in a polytropic process with n = 1.667. How much heat transfer is involved?

Answer 1

C.V. Helium gas, this is a control mass.

Energy equation: m(u2 – u1) = 1Q2 – 1W2

Process equation: PVn = constant = P1Vn 1 = P2Vn2