Experimental validation of heat exchanger models for refrigerator/freezers

Separate experiments with a condenser and an evaporator showed that changes in refrigerant-side heat transfer coefficients produced variations in overall heat transfer resistance of up to 20% over a wide range of operating conditions. An extensively instrumented refrigerator was used to gather air- and refrigerant-side temperature, pressure, power, and refrigerant mass flow measurements to provide in situ calorimetry for 95 operating conditions. These operating conditions included three different refrigerator charges that provide a variety of evaporator and condenser outlet conditions. Accounting for the variation in refrigerant-side heat transfer coefficients produced better results than assuming that the heat transfer coefficients were constant. The variable-conductance models developed here can be used to predict changes in performance resulting from the use of alternative refrigerants and different heat exchanger tube dimensions.