Question

A watercooled air compressor takes air in at 70 F, 14 lbf/in.2 and compresses it to 80 lbf/in.2. The isothermal efficiency is 80% and the actual compressor has the same heat transfer as the ideal one. Find the specific compressor work and the exit temperature.

Answer 1

Ideal isothermal compressor exit 80 psia, 70 F

Reversible process: dq = T ds => q = T(se – si)

As same temperature for the ideal compressor he = hi ⇒

w = q = -63.3 Btu/lbm => wac = w /η = - 79.2 Btu/lbm, qac = q

Now for the actual compressor energy equation becomes