利用喷射提高跨临界二氧化碳系统的性能

建立了跨临界二氧化碳蒸气压缩／喷射制冷循环中喷射器的数学模型，讨论了系统稳定运行时的蒸发温度、气体冷却器内压力及其出口温度、过热度等因素对系统性能的影响．结果表明，当工作流流量同扩压段出口蒸气流量相等时系统能够稳定运行．同时，升高蒸发温度能提高系统性能，但蒸气压缩／喷射循环相对简单循环性能系数的提高程度变小；气体冷却器内压力存在最优值，但降低压力能够增大系统性能的改善程度；升高气体冷却器出口温度会降低系统性能，但蒸气压缩／喷射循环相对简单循环性能系数的提高程度将先增大，然后迅速减小．与上述因素相比，过热度的影响很小．

Performance of Transcritical Carbon Dioxide System with Ejector

The mathematical model of the ejector in the transcritical carbon dioxide vapor-compression/ejection refrigeration cycle was established, and the effects of evaporating temperature, heat rejection pressure, gas cooler outlet temperature and the superheat on the system performance were discussed as the system works in steady status. The results show that the system runs steadily when the driving flow mass flow rate equals to the diffuser outlet vapor flow mass flow rate. And the increasing evaporating temperature enhances the system performance, but reduces the improvement of the system performance compared with the conventional cycle. An optimum heat rejection pressure exists, and decreasing heat rejection pressure improves system performance. A higher gas cooler outlet temperature worsens the system performance, the improvement of system performance increases firstly, and then reduces rapidly. The effect of the superheat is much slighter than that of above mentioned factors.