An ideal vapor compression refrigeration cycle is being oper

An ideal vapor compression refrigeration cycle is being operated between the pressures of 500kPa and 1 MPa. The system delivers 10 KW of cooling. If the refrigerant is R-134a, what is themass flow rate?

Solution

>> In Ideal Vapour Compression Refrigeration Cycle,

Entry in Compressor is at Pressure, P1 = 500 kPa and is at saturated vapour state

So, from properties of refrigerant R-134a,

h1 = 259.36 KJ/Kg

>> Now, State of fluid coming to condenser is wet steam and it comes from a dry liquid saturated state at pressure, P3 = 1 MPa

So, Entropy is same, as process is isentropic

=> s3 = s4

=> s4 =0.3920 KJ/Kg-K

=> 0.3920 = 0.2802 + x*(0.9242 - 0.2802)

=> x = 0.1736

So, h4 = 73.32 + 0.1736*(259.36 - 73.32)

=> h4 = 105.617 KJ/Kg

As, Q = m*(h2 - h4)

=> 10 = m*(259.36 - 105.617)

=> m = Required Mass Flow Rate = 0.0654 Kg/s