Question

An initially empty cylinder is filled with air from 70 F, 15 psia until it is full. Assuming no heat transfer is the final temperature larger, equal to or smaller than 70 F? Does the final T depends on the size of the cylinder?

Answer 1

This is a transient problem with no heat transfer and no work. The balance equations for the tank as C.V. become

Continuity Eq.: m2 – 0 = mi

Energy Eq.: m2u2 – 0 = mi hi + Q – W = mi hi + 0 – 0

Final state: u2 = hi & P2 = Pi

T2 > Ti and it does not depend on V