Study of moist air transfer and its thermal load under refrigerator door closing and opening conditions

This study conducted a detailed experimental study of moist air transfer and its thermal loads in refrigerators under door closing and opening conditions. Employing trace gas technology with CO₂ as the tracer, a mass balance equation for CO₂ was formulated to determine the air transfer rate. It was founded that under door closing conditions, the primary pathways for moist air transfer were the gasket and defrosting drainage tube. The proportion occupied by the defrosting drainage tube was closely related to its structural design, reaching from 29.5 % to 88.5 %. The mass transfer rates in the pull-down and intermittent refrigeration processes were 133.018 g h⁻¹ and 102.920 g h⁻¹. Under door opening conditions, the averaged mass transfer rate during the opening-closing process is observed to range from 65.598 to 150.076 g s⁻¹, approximately 2300–5200 times higher than the door closing conditions. Over a 24 h operation period, the accumulative thermal load caused by moist air transfer was 417.054 kJ, with the pull-down, intermittent refrigeration, and door opening-closing processes contributing 5.7 %, 40.2 %, and 54.1 %. These findings provide essential data support for understanding the thermodynamic behavior of moist air transfer within refrigeration systems under varying door operation conditions.