Dual-temperature air circulation and preventing moisture intake to solve frosting issue in low-temperature refrigerators

As temperature decreases, severe frosting on the cabinet walls of refrigerators affects normal use. Frosting in low-temperature refrigerators is closely related to moisture transfer. This study focuses on a refrigerator set at −40 °C to −18 °C. Firstly, the frosting phenomena and moisture transfer processes at −40 °C and − 18 °C were compared. Then, the tracer gas method was employed to quantify the moisture intake and its distribution at −40 °C. Results show that 64.3 % of the moisture enters during the door opening process and 65.7 % of the entering moisture deposits as frost on the cabinet walls, while only 34.3 % transfers to the evaporator for centralized melting. Finally, two methods are proposed to solve the frosting issue. The first is to activate the dual-temperature air circulation for 1 h after each door opening-closing operation, which can accelerate the moisture transfer to the evaporator. Experiments confirm that this method can redistribute the frosting ratio on the walls from 65.7 % to 36.0 % and maintain door opening force below 70 N. The second is to keep the fan on during each door opening process to prevent moisture intake. The computational fluid dynamics (CFD) simulation results show that this method can reduce moisture intake by 28.6 %. This study provides two novel methods for solving the frosting issue of low-temperature refrigerators, which can improve their reliability.