Steam Engine Work

Question

In a steam engine the pressure + volume of steam equal the equation PV1.4 = k. Calculate the work done by the engine during a cycle when the steam starts at a pressure of 120 lb/in^22 and a volume of 300 in^3 and expands to a volume of 700 in^3.

Answer 1

k = PV^1.4

Start: P = 120, V= 300

k = (120)(300)^1.4

To calculate the work of expanding pressure

W = ∫PdV from V₁ to V₂, V₁= 320, V₂= 700

P = kV^-1.4

So,

W = k ∫V^-1.4dv = k[-V^-0.4/0.4] evaluated from 300 to 700

W = (-2.5)(120)(300^1.4)[700^-0.4 - 300^-0.4]