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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。
The theoretical research of transcritical CO2 vapor compression / injection refrigeration cycle, especially the numerical simulation of injector operating characteristics, is helpful to improve the refrigeration performance of the experimental system. The injector model was established by using the conservation of momentum and the energy conservation equation, taking into account the coupling between injector outlet dryness and injection coefficient at steady state. The effects of different CO2 cooling exothermic pressures, evaporation temperatures, ejector nozzle efficiency and diffuser efficiency on the theoretical cycle performance were compared. The theoretical analysis shows that the optimized injection coefficient can significantly improve the refrigeration cycle performance, and the influence of evaporation temperature and CO2 cooling exothermic pressure on the system performance is relatively large. The system performance coefficient and the injector injection coefficient have significant influences on the nozzle efficiency and diffuser efficiency Change is not sensitive.