短管节流件的流量特性

制冷剂流经短管节流件时具有两相临界流动非均匀性、非平衡性的特点并存在阻塞情况 ,而影响质量流量的主要参数有上游压力、下游压力、过冷度或干度以及短管几何尺寸等 .近年来有关制冷剂流经短管节流件的两相流动模型主要有由实验结果直接关联的半经验模型和基于一些假设而建立的分析模型 ,而它们都是针对某种工质而言的 ,不适应当前空调制冷及热泵系统所采用的工质种类较多的状况 .因此 ,建立普适性好、在热力学参数变化较宽的范围内仍有较高精度的质量流量模型是有待进一步研究解决的问题 .

Flow characteristics of short tubes

The heterogeneity,the non equilibrium and the blockage state which formed the features of two phase critical flow are analyzed when refrigerants flow through short tubes and upstream pressure,downstream pressure,supercooled temperature or quality coefficient and geometrical dimensions of short tube orifices as the main parameters effects on mass flow rate are indicated.The refrigerant two phase flow models through short tubes in recent years mainly included the semiempirical models which are correlated directly with the experimental results and the analysis models which are built based on some assumptions.However,all of them are individually applicable to certain refrigerant and not suitable for the situation of using too many kinds of refrigerants in air conditioning,refrigerating and heat pump systems scope.Therefore it would be made further research to establish the mass flow rate models which possess good and general adaptability and higher precision within a wide range of the thermodynamic parameter variation.