A liquidtosuction heat exchanger is installed in an R134a sy

A liquid-to-suction heat exchanger is installed in an R-134a system to cool liquid that comes from the condenser with vapor that flows from the evaporator. The evaporator generates 10 tons (35.17 kW) of refrigeration at 30F (-1.1C). Liquid leaves the condenser saturated at 100F (37.8C), vapor leaves the evaporator saturated, and vapor leaves the heat exchanger at a temperature of 50F (10C). What is the flow rate of the refrigerant?

Solution

Heat extracted = 35.17 kW

Specific Enthalpy of the refrigerant on exit to condensor, h₃ = 105 kJ/kg

Specific Enthalpy on entry to evaporator, h₄ =  h₃ = 105 kJ/kg

Specific Enthalpy on exit to evaporator ,h₁ = 50.2 kJ/kg

Enthalpy difference = h₄ - h₁ = 54.8 kJ/kg

Mass Flow rate of Refrigerant = Heat generated by evaporator/Enthaly difference = 35.17/54.8 = 0.642 kg/sec