Saturated R134a vapor at 2 MPa is compressed to 8MPa and 50

Saturated R-134a vapor at .2 MPa is compressed to .8MPa and 50 degrees celsius. If the flow rate is .22kg/s and the power consumption is 9.0 Kw. How much is the rate of heat transfer in (kj/s) during this process? Is heat transfer to the compressor or out of the compressor?

Solution

Q = W +h2-h1

h1= 244.5kj/kg ( at. 2Mpa hg)

h2=286.7kj/kg (at. 8Mpa, 50 C)

Now Q = w + m(h2-h1)

Q= 9+. 22(286.7-244.5)

But in this case work is done on the system so w= -ve

So Q= -9+9.284=0.287kw

So heat to the compressor