Design and Research of a New Cold Storage: The Phase-Temperature Storage (PTS) to Reduce Evaporator Frosting

This paper introduces a novel cold storage: phase-temperature storage, which is characterized by its distinctive coupling jacket structure that connects the sub-storehouse units to the main storehouse. This innovative design facilitates heat transfer while effectively inhibiting mass transfer. Experimental results indicate that polyethylene film, with a thermal conductivity of 0.42 W/m·K, is a more suitable material for constructing sub-storehouses. Enhancing the surface area of the sub-storehouse and increasing convective wind speed are identified as key factors for improving convective heat transfer within the sub-storehouse. Moreover, the optimized design ensures a more uniform temperature distribution inside the sub-storehouse. In contrast to conventional cold storage, the defrosting unit in phase-temperature storage consumes only 5.72 units of energy under equivalent conditions, compared to 154.02 units for conventional cold storage. This demonstrates that the energy expenditure during the defrosting process of phase temperature storage is less than 4% of that required by conventional cold storage, achieving an energy savings rate exceeding 96%. Under identical circumstances, conventional cold storage consumes a total of 36.359 units of electrical energy for defrosting, with 34.231 units being released as defrosting waste heat into the cold storage environment, resulting in a loss rate of approximately 94.13%. Based on apple preservation experiments, phase-temperature storage exhibited significantly superior performance compared to conventional cold storage in terms of apple respiratory peak, weight loss rate, hardness, and TSS content, with respective values of 17.05 CO₂ mg·kg^-1·h^-1, 2.89%, 9.29 N, and 16.3%. In contrast, the conventional cold storage group recorded values of 18.15 CO₂ mg·kg^-1·h^-1, 5.16%, 8.42 N, and 14.9%. These results highlight the exceptional freshness-retention capabilities of phase-temperature storage, underscoring its considerable potential for application in storage systems.