Steam in a piston-cylinder assembly undergoes a polytropic process. Kinetic and potential energy effects are negligible. For the process, determine the work and heat transfer, each in Btu per lb of steam.
p1 = 100 lbf/in2
p2 = 40 lbf/in2
v1 = 4.934 ft3/lb
v2 = 11.04 ft3/lb
u1 = 1136.2 Btu/lb
u2 = 1124.2 Btu/lb
ΔE = Q - W
W = ∫v1v2pdV
The Attempt at a Solution
Since the process is polytropic, PVn = constant = p1V1n = p2V2n
Thus, W = ∫v1v2(constant/Vn)dV = (p2V2 - p1V1)/(1-n)
I used the relation p1V1n = p2V2n to find n, which gives me n = 1.14
Then, my plan is to plug the numbers into my integrated work function, but I am extremely confused on the units of this and I'm not really sure if I'm even working in the right direction. Basically I've gotten stuck at this point. Any help would be much appreciated.