关键结构参数对喷射器性能影响及结构优化

Influence of Key Structural Parameters on Ejector Performance and Structure Optimization

蒸汽喷射器是蒸汽热压缩低温多效蒸馏海水淡化系统的关键部件,其性能将直接影响系统性能。喷射器的结构参数对喷射器性能有较大影响,优化结构参数是提高喷射器性能的有效途径之一。本文采用CFD方法建立了应用于蒸汽热压缩低温多效蒸馏海水淡化系统蒸汽喷射器的二维轴对称数值模型,对固定工况下不同喷嘴出口位置、等截面积、混合室直径和长度三个关键结构参数对喷射器性能的影响进行分析,并进行了优化设计。结果表明:随着喷嘴出口位置距混合室入口截面之间距离的增大,喷射系数先增大后减小,存在最优值;喷射系数随等截面积混合室直径的增大而增大,等截面积混合室长度对喷射系数无明显影响;蒸汽喷射器的最优结构参数组合所得喷射系数为0.582,与优化前喷射器的喷射系数0.408相比,提升了42.65%。

Steam ejector is the key component of multi-effect distillation with thermal vapor compression seawater desalination system,and its performance will directly affect the system performance.The structural parameters of the ejector have great influence on the performance of the ejector.Optimizing the structural parameters is one of the effective ways to improve the performance of the ejector.In this work,a two-dimensional axisymmetric numerical model of steam ejector used in multi-effect distillation with thermal vapor compression seawater desalination system is developed using CFD method.The influence of three key structural parameters on the performance of the ejector under a fixed operating condition is analyzed,and the nozzle exit position,constant area mixing chamber diameter and length are optimized.The results show that with the increase of the distance between the nozzle exit position and the inlet section of the mixing chamber,the entrainment ratio first increases and then decreases,and there is an optimal value.The entrainment ratio increases with the increase of the constant area mixing chamber diameter,and the constant area mixing chamber length has no obvious effect on the entrainment ratio.The entrainment ratio obtained by the combination of optimal structural parameters is 0.582,which is 42.65%higher than the entrainment ratio 0.408 before optimization.