The performance and feasibility of the air refrigeration system applied to vaccine cold storage were explored and compared with a cascade refrigeration system based on characteristics of safety and environmental protection

local availability of the refrigerant

and no temperature fluctuation caused by evaporator defrosting. The accuracy of the thermodynamic model was verified by comparison with the literature. The research results showed that when the ambient temperature was 35 ℃

the coefficient of performance (COP) of the air refrigeration system using three-stage compression (total pressure ratio of 8) and a regenerator (pinch point temperature difference of 5 ℃) was 0.23–0.38 and varied linearly within the storage temperature range of -70–10 ℃. This COP is 25.8% less than the COP of the cascade refrigeration system at -70 ℃. When the ambient temperature increased by 10 ℃

the COP and cooling capacity of the air refrigeration system were reduced by 5% and 3%

respectively. This difference was considerably less than that of the cascade refrigeration system (reduced by 15% and 8%

respectively); thus

the impact of ambient temperature on the storage temperature was less sensitive. The air refrigeration system can change the air supply pressure difference to a uniform supply of air in the vaccine cold storage by adjusting the air outlet state. Compared with the cascade refrigeration system

the cost and power consumption of the fan equipment in air refrigeration systems are less

and the adjustment is more convenient. Therefore

the air refrigeration system applied in the low-temperature storage of vaccines in the temperature range below -70 ℃ shows advantages of high reliability and stability. It is especially suitable for cold-chain logistics equipment for the low-temperature transportation of vaccines.