Design of drain hole for household refrigerator fan module based on experiments and CFD simulation

Abstract

In refrigerator, the frost accumulated at the evaporator surface and melt with the defrost heater over the operation cycles. While the undesirable airflow from a drain hole in the refrigerator fan (R-fan) module can deteriorate the frost layer formation and defrost process. The thermal resistance increased by the frost layer can significantly affect the cooling capacity and power consumption of refrigerators. Different from the research on frost generation mechanisms, this study focused on product performance related to frost accumulation and flow features. The relationship between frost accumulation and airflow from drain hole was investigated by combining the experimental method and computational fluid dynamics (CFD) analysis without phase change. A new drain hole design with a circular shape was selected considering Laplace pressure for stable drainage. In CFD results, proposed model shows significant reduction of disorderly airflow around the evaporator and improvement of the performance including the flow rate delivered to the refrigerator and temperature distribution around the evaporator. The validation test of the proposed model fabricated by 3D printer was also conducted. The results corresponded well with the simulation result. The in-situ experimental results showed that the flow loss from the R-fan module drain hole and the average defrost cycle time were improved with a reduction of 28.7% and 8.0% compared with the original model, respectively. Although the internal structure of different products may be slightly different, the research results can be applied to products with similar defects for product development and improvement.