Moist air transfer and frost distribution characteristics in low-temperature refrigerator

The application of low-temperature refrigerators set below −30 °C is increasing. Compared to conventional refrigerators set at 5 °C/−18 °C, these low-temperature units face more severe frost issues within their cabinets, which have received less attention. This study focuses on the frost issue in a low-temperature cabinet at −40 °C. Firstly, tracer gas technology and computational fluid dynamics (CFD) simulation were employed innovatively to obtain the moist air transfer rate. Based on this, the distribution ratio of frost between the cabinet walls and evaporator was analyzed. The results show that the moist air transfer rates entering the cabinet through the gasket, defrosting drainage tube, and door opening-closing process are 35.62 g·h⁻¹, 7.12 g·h⁻¹, and 295.7 g per opening. Among these, 67.5 % of the water vapor condenses into frost on the cabinet walls. This increases the difficulty in opening the door, affecting the user experience. Implementing −30 °C and −18 °C frost transfer modes can reduce the frost ratio on the cabinet walls to 52.7 % and 11.4 %. The average door opening force also decreased from 91.3 N to 70.6 N and 51.1 N. This study first explores laws of the moist air transfer rate and frosting distribution in −40 °C low-temperature refrigerator, establishes theoretical foundations to address the frosting issue within cabinet of such refrigerators.