Question: A counter flow evaporator based on R-134a refrigerant has been designed with a capacity of 12 tons of refrigeration. The evaporator is used to cool 50 vol% ethylene glycol solution (cp = 0.775 Btu/(lb ?F) that enters the heat exchanger at 55?F with a mass flow rate of 20000 lb/h. The R-134a enters the heat exchanger at 35?F with a quality of 0.1 and leaves with a quality of 0.65. Estimate the exit temperature of the ethylene glycol solution, the mass flow rate of the refrigerant, and the increase in efficiency of the heat exchanger if the surface area of the evaporator were doubled. Further Information: The R-134a refrigerant has experienced a phase change.