Application and Validation of Stirling Cryocoolers in Domestic Refrigerators

Stirling cryocoolers have the advantages of fewer moving parts, oil-free, single-phase heat transfer, a large refrigeration temperature range, convenient and adjustable refrigeration capacity, and high refrigeration efficiency. Therefore, they have broad application prospects in commercial and domestic refrigeration systems. To meet the demands of low-temperature refrigerators, this study developed a multi-temperature zone refrigerator with a vapor compression refrigeration system and a Stirling cryocooler. The performance of the Stirling cryocooler was tested. The designs of the heat dissipation and cooling conduction structures were optimized, and the refrigerator′s overall performance was examined. Moreover, the influences of input power and ambient temperature on the performance of the Stirling cryocooler were investigated. The results showed that the cooling output and coefficient of performance (COP) of the Stirling cryocooler increased with an increase in the cold-end temperature, and increasing the input power provided a higher cooling capacity but decreased the COP. Under an ambient temperature of 43 ℃, the cooling capacity of the Stirling cryocooler was 28.97 W with a COP of 0.37 when the cold-end temperature was-60 ℃. Heat transfer structures at the cold and hot ends of the Stirling cryocooler based on heat-pipe technology were also proposed, and the simulation showed that the proposed structures for heat dissipation and cooling conduction met the system design requirements. Finally, an experimental test of refrigerator performance was conducted. A no-load experiment at an ambient temperature of 32 ℃ showed that the pull-down time of the low-temperature room was 28% shorter than that of the freezer room. Under an ambient temperature of 43 ℃, the low-temperature room reached an average temperature of -64.5 ℃, and the power consumptions of the Stirling cryocooler and refrigerator were 2.33 kW·h/d and 4.13 kW·h/d, respectively.