水蒸气喷射制冷系统中蒸汽喷射器性能研究

Performance Analysis of A Steam Ejector for A Steam Eject Refrigeration System

利用自然工质的水蒸气喷射制冷系统可有效利用低品位余热制冷,但系统性能受制于关键部件喷射器的性能,而有关研究中采用的理想气体模型,不能真实反映内部情况。通过建立蒸汽喷射器的湿蒸汽模型,着重研究流体参数对蒸汽喷射器引射性能的影响,并比较不同模型的差异。结果表明:湿蒸汽模型的引射系数高于理想气体模型6.92%;蒸汽喷射器存在临界压力值,超过临界值后,随着流体出口压力升高,引射系数下降;随着入口压力升高,引射系数先增加后减小,存在最佳工作流体入口压力;随着引射流体入口压力的增加,引射系数增加;引射系数随工作流体过热度的增加而增长,但随引射流体过热度的增加无明显变化。

The steam jet refrigeration system charged with natural working fluid can utilize the low-grade waste heat effectively,but the system performance still depends on the steam ejector as the key component.The ideal gas model was adopted in most investigations,which cannot reflect the real working situation in the steam ejector.A new wet steam model for a steam ejector was built up in this paper.The effects on the entrainment ratio of the steam ejector from fluid parameters were analyzed and the two different models were compared.The results show that the entrainment ratio of the wet steam model is 6.92%higher than that of the ideal gas model.The critical pressure point exists in the ejector,and the entrainment ratio decreases with the increasing fluid outlet pressure beyond the critical pressure point.The entrainment ratio first increases and then decreases with the increasing inlet pressure,and there is an optimal steam inlet pressure point.When the primary steam inlet pressure increases the entrainment ratio increases.The entrainment ratio of the ejector increases with the increasing superheat level of the primary steam inlet,but changes little with the increasing superheat level of the ejected steam.