液液引射器性能的数值模拟与实验

Numerical simulation and experimental investigation on performance of liquid-liquid ejector

建立了液液引射器的三维数学模型,采用R134a制冷剂作为工质,模拟引射器主要结构参数与引射性能之间的变化关系.模拟结果表明:引射系数随喷嘴出口直径的减小而急剧增大,随混合室直径的增大而增大,随喷嘴与混合室之间距离的增大急剧下降;引射系数随着工作流体流量、喷嘴长度和扩散室长度的增大而缓慢上升;混合室长度对混合流体的压力场有较大影响,为使混合流体获得最佳的压力场,混合室最佳长度取45 mm.搭建了水平管降膜式空气源冷热水测试机组,试验结果表明:该引射器具有优良的引射性能;制冷系统负荷随着循环喷淋量的增加而增大,系统的性能系数随着循环喷淋量的增大呈现先增后减的趋势.

A three-dimensional model of the ejector is proposed.And then the relations of main structural parameters with the jet performance of the ejector are simulated by using refrigerant R134a as the working fluid.Simulation results indicate that the entrainment ratio increases sharply with the decrease of the nozzle exit diameter,increases gradually with the increase of the mixing section di-ameter,and descends quickly with the increase of the distance between the nozzle exit and the mix-ing section inlet.And the entrainment ratio ascends slightly with the increase of the working fluid flow rate,nozzle length and diffuser length.Moreover,the mixing section length has a strong influ-ence on the pressure of the mixed fluid.To obtain the optimal pressure field of the mixing fluid,the optimum length of the mixing section is 45 mm.Finally,an air-source falling-film heat pump unit is established,and the experimental results show that the performance of the ejector is remarkable.And that the cooling load increases gradually with the increase of the circular spraying flow rate,moreo-ver,the performance coefficient increases first,and then decreases with the increment of the circular spraying flow rate.