用于微通道换热器的循环流道分流器的设计方法与应用效果

Design method and application effects of cyclic channel distributor for micro-channel heat exchangers

在家用和商用空调领域中常采用分流器实现多路微通道换热器中制冷剂的分流。分流器应用中最普遍的问题是制冷剂分流不均匀。提出一种利用循环流道实现制冷剂均匀分流的分流器。在传统圆筒式分流器的基础上,设计了循环流道,使制冷剂形成离散泡状流并均匀分流到每根扁管中。新型分流器的关键几何尺寸包括喷孔直径和上行流道水力直径。通过离散泡状流的形成条件推导出喷孔直径的计算公式;通过两相流循环流动的形成条件推导出上行流道水力直径的计算公式。给出新型分流器的设计实例,并通过试验对分流器性能进行验证。试验结果表明分流器进口制冷剂质量流量为14.0、18.0、22.0 g/s时,新型分流器的不均匀度分别为比传统分流器下降46.8%、32.0%、24.4%。

Distributors are widely used in room and commercial air conditioners for the refrigerant flow distribution among multi-paths of micro-channel heat exchangers.The most common problem in the distributor application is the non-uniform distribution of refrigerant flow.In this paper a novel distributor with a cyclic channel was proposed to achieve the uniform refrigerant distribution.Based on a traditional cylinder-type distributor,the cyclic channel was designed to construct a dispersed bubble flow pattern and allocate the dispersed bubble flow evenly into each flat tube.The key geometric size of the novel distributors includes the diameter of spray holes and the hydraulic diameter of upward channel.In this paper,the spray diameter is deduced from the formation criterion of dispersed bubble flow and the hydraulic diameter of upward channel is deduced from the formation condition of circulating flow.A design case is provided by using the deduced equations,and the distribution performance of the proposed distributor is tested by experiments.The experimental results prove that the unevenness of the proposed distributor is 46.8%,32.0%and 24.4%lower than that of the traditional distributor respectively when the mass flow rate of inlet is 14.0,18.0 and 22.0 g/s.