船舶多温冷库新型自复叠制冷循环的研究

Studies on a New Type of Auto-Refrigerating Cascade Circle for Marine Multi-Stage Temperature Refrigerator

针对传统船舶一机多温冷藏系统在不同蒸发压力下提供不同蒸发温度所存在的问题,提出将改进的自复叠制冷循环用于船舶多温冷库.新型自复叠制冷循环使用非共沸混合工质,可以在相同的蒸发压力下提供不同的蒸发温度.根据船舶双温冷库的间室温度,选取R600a和R32组成的非共沸混合工质作为制冷剂,并对系统进行了流程设计、模拟计算,得到了设计工况下蒸发压力、冷凝压力、压缩机压缩比和性能系数随R600a质量分数变化的曲线,发现当R600a/R32的质量分数为0.7/0.3时系统的综合性能最优.为了更好地满足船舶储存食物的温度要求,设计了自复叠三温冷库的流程图,为进一步研究三温冷库提供了新方法.

To solve the problems existing in a typical marine multi-stage temperature refrigeration system which provides different evaporation temperatures under different evaporation pressures, a new type of auto-refrigerating cascade cycle was proposed. The new cycle, employing non-azeotropic mixture refrigerant, can provide different evaporation temperatures under an evaporation pressure. According to the temperature of compartments of marine two stage temperature refrigerator, the non-azeotropic mixture refrigerant composed of R600a and R32 was employed. The flow chart of the system was designed and the performance of the system was calculated. The curves expressing the changes of evaporation pressure, condensation pressure, pressure ratio of compressor, and coefficient of performance with different mass percent of R600a were obtained. The results show that the general performance is optimal when the mass proportion of R600a/R32 is 0. 7/0. 3. To meet the requirement of temperature of food stored in marine better, the flow chart of auto-refrigerating cascade cycle for three-stage temperature refrigerator was also designed.