Question

A 4 kg/s steady flow of ammonia runs through a device where it goes through a polytropic process. The inlet state is 150 kPa, -20°C and the exit state is 400 kPa, 80°C, where all kinetic and potential energies can be neglected. The specific work input has been found to be given as [n/(n-1)] ∆(Pv).

(a) Find the polytropic exponent n

(b) Find the specific work and the specific heat transfer.  

Answer 1

C.V. Steady state device. Single inlet and single exit flows.

From the polytropic process equation and the two states we can find the exponent n:

Before we can do the heat transfer we need the work term