跨临界CO2蒸气压缩/喷射制冷循环理论分析

对跨临界CO2蒸气压缩/喷射制冷循环的理论研究,特别是对喷射器工作特性进行数值模拟,有助于改善实验系统的制冷性能。使用动量守恒和能量守恒方程建立了喷射器模型,同时考虑了系统稳态下喷射器出口干度和喷射系数的耦合关系。比较了不同的CO2冷却放热压力、蒸发温度、喷射器喷嘴效率和扩压效率等对理论循环性能的影响。理论分析表明:优化的喷射系数能显著改善制冷循环性能,蒸发温度和CO2冷却放热压力对系统性能的影响比较大,系统性能系数和喷射器喷射系数对喷射器的喷嘴效率和扩压效率的变化不敏感。

Theoretical analysis of a transcritical CO2 vapor compression/ejection refrigeration cycle

A transcritical CO_2 vapor-compression/ejection refrigera-tion cycle was studied theoretically with an accurate model of the ejector to improve the system's refrigeration performance.The ejector model was based on the momentum and energy conservation laws.The model couples the refrigerant quality at the ejector exit and the ejector entrainment ratio.The analysis was used to study the variations of the cycle performance for various heat rejection pressures,evaporation temperatures,nozzle efficiencies,and diffuser efficiencies.The ejector entrainment ratio significantly affects the refrigeration effect with an optimum ratio for ideal system performance.The evaporation temperature and the heat rejection pressure obviously affect the system refrigeration performance.The ejector nozzle efficiencies and diffuser efficiencies have little influence on the cycle performance.