Theoretical And Experimental Study Of Distribution Characteristics In Microchannel Parallel Flow Heat Exchanger And Its T-Juction Tube

Microchannel parallel flow heat exchanger has a wide application prospect in home air conditioning and automotive air conditioning.Compared with the commonly finned tube heat exchanger used in home air conditioning,it has the advantages of low manufacturing cost,convenient material recovery,excellent surface-to-volume ratio and high heat transfer efficiency.In the field of automotive air conditioning,compared with traditional parallel flow heat exchanger,micro channel parallel flow heat exchanger has smaller volume and greater heat transfer area,save valuable space of vehicle interior,increase thermal efficiency.At present,the biggest problem in the use of microchannel parallel flow heat exchanger is refrigerant flow mal-distribution.It will seriously affect the heat transfer efficiency of the heat exchanger and performance of air conditioner.In view of this phenomenon,the experiment and theory of distribution characteristics of a flat T-junction tube and a microchannel parallel flow heat exchanger are studied in this paper.In order to study the influencing law and mechanism of the distribution characteristics of the microchannel parallel flow heat exchanger,a T-junction tube flow distribution and pressure characteristic experiment system with a microchannel flat tube is built.The experimental results show that in the flat T-junction tube,the single phase flow is not only related to the flow ratio in the divergent tube and the main tube,but also related to the inlet Reynolds number of the divergent tube.The flow of the two phase flow is only related to the flow ratio in the divergent tube and the main tube.In this paper,the phase separation model of Hwang S T^[21]is corrected according to the experimental data.The calculation accuracy is nearly 50%higher than before the model correction when calculating the separation ratio of gas phase and liquid phase.Based on the T-junction model of T tube,combined mass equation and pressure equation,a suitable algorithm is proposed to establish the two-phase flow distribution model of parallel flow heat exchanger.The results show that the overall simulation model of the parallel flow heat exchanger in this paper can be used to simulate the mass flow distribution of parallel flow heat exchanger on the premise of not knowing the mass flow of the divergent pipes.On this basis,the influence of quality and mass flow on the distribution of parallel flow heat exchanger is analyzed.The results show that the influence of quality on the distribution of parallel flow heat exchanger is not significant.When the quality is constant,the flow distribution of parallel flow heat exchanger can be improved by increasing the mass flow rate of the fluid.