内部不可逆损失对喷射器性能影响理论分析

喷射器作为喷射式制冷系统的关键部件，其性能对系统性能有着重要影响。建立了采用实际气体性质且考虑喷射器内两相存在的喷射器性能预测模型，并定义了喷射器内部各部分不可逆损失，利用理论模型对喷射器内部各部分不可逆损失程度对喷射器性能的影响进行理论分析，讨论了喷射器内部各部分不可逆损失程度对喷射系数、喷射器效率和喷射器出口背压的影响。结果表明，工作流体在喷嘴中的不可逆损失以及引射流体在吸入室的不可逆损失对喷射系数影响较大，扩散段不可逆损失和混合段不可逆损失对喷射系数几乎没有影响；随着喷射器内部各部分不可逆损失的减小，喷射器效率增大，同时可以使喷射器出口背压提高。

Theoretical analysis on impact of irreversibility on ejector performance

Ejector is the key component of ejector refrigeration system.Its performance is directly of relevance to the system efficiency.In the present work, a new theoretical model is proposed to analyze the impact of internal irreversibility of the ejector on its performance, including entrainment ratio, ejector efficiency and ejector back pressure.In the proposed model, real gas characteristic is used, and the existence of two phases is also considered for the prediction of ejector performance.Results show that the irreversibility of primary flow through the converging-diverging nozzle and the irreversibility of secondary flow expansion in suction chamber have great impact on entrainment ratio, the irreversibility of mixed flow in mixing chamber and diffuser almost has little influence on the entrainment ratio.And with the decrease of the internal irreversibility in each part of the ejector, ejector efficiency increases and the ejector back pressure increases as well.