Dual Evaporator Household Refrigerator Performance Testing and Simulation

Abstract

The performance of dual evaporator household refrigerators was studied experimentally and by numerical simulation. This study considers only serial connection where the refrigerant flows through the fresh food evaporator and then through the freezer evaporator without a pressure drop between the evaporators. The prototype tested had insufficient compressor power and a higher cabinet thermal conductance than designed. In addition, the exit of the freezer evaporator was always two-phase affecting compressor performance. However, control of the fresh food cabinet air temperature was achieved through turning the fan off and on during operation. This fan cycling affected both the performance of the prototype and the charge distribution inside the system. The data from the tests was used to check the accuracy of a numerical model of dual evaporator refrigerators. It was shown that the accuracy of the model could be improved through various adjustments. However, uncertainty about the compressor performance limited the accuracy to between 10 and 20 percent. This model was then used to simulate the performance of the refrigerator as originally designed and with larger and smaller evaporators. In general, charge requirements increased with evaporator size as did the system???s sensitivity to ambient temperature. Increasing the fresh food evaporator size did not significantly increase COP but did increase capacity