A commercial refrigerator with refrigerant 134a as the working fluid is used to keep the refrigerated space at -35C by rejecting waste heat to cooling water that enters the condenser at 18C at a rate of 0.25 kg/s and leaves at 26C. The refrigerant enters the condenser at 1.2MPa and 50C and leaves at the same pressure subcooled by 5C. If the compressor consumes 3.3kW of power, determine:
a) the mass flow rate of the refrigerant
For the condenser, I have:
Water:
temp in = 18C
temp out = 26C
mass flow rate = 0.25 kg/s
Refrigerant:
temp in = 50C
temp out = 5C
P in = P out = 1.2 MPa
mass flow rate = ? (looking for)
I can find the enthalpy/h values for the refrigerant through a table since I have T and P, and for water I have mass flow rate but I can't find the h values because I don't have enough information. So when I do an energy balance a la m_water(h1-h2) = m_134a(h3-h4) I am missing too many things (the m on the 134a side and the h's on the water side). Do you guys know how I could solve this another way?