COP-based optimization of accelerated flow evaporators for household refrigeration applications

This paper reports an investigation on the impact of an alternative evaporator design, the so-called Accelerated Flow Evaporator (AFE), on the performance of household refrigerators. In this novel evaporator concept, the air-side cross-section area decreases with the distance from the air flow inlet, accelerating the air as it flows across the tubes and hence improving the air-side local heat transfer coefficient. An AFE heat transfer and pressure drop calculation method proposed elsewhere has been incorporated into an overall system simulation model to assess the impact of the evaporator geometry on the system COP. The results were compared with experimental data obtained in a top-mount refrigerator. The predictions of working pressures, power consumption, cooling capacity and COP agreed with the experimental data to within ±10% error bands. The model was subsequently used in an optimization exercise of the AFE geometry that considered both the system COP and the evaporator mass of material.