Experimental And CFD Investigation Of Flow Mechanism Of Oscillating Flow In Heat Exchanger In Pulse Tube Refrigerator

In recent years,the field of space science is developing rapidly,and the performance requirements of space detectors are increasing day by day.Therefore,the performance and efficiency of pulse tube chillers which are widely used in space refrigeration have higher requirements.As one of the key components of pulse tube refrigerator,the performance of heat exchanger directly affects the balance temperature of refrigerator.Therefore,the study of fluid flow and heat transfer in heat exchanger plays an important role in the design and optimization of pulse tube refrigerator.To solve these problems,this study combined the numerical simulation of computational fluid dynamics with the experimental measurement of hot-wire anemometer,and obtained the detailed information of the internal flow field of the heat exchanger by establishing the three-dimensional model of the internal fluid of the heat exchanger,so as to study the influence of the change of the structure of the heat exchanger on the performance of the heat exchanger.In this paper,the fluid inside the heat exchanger at the hot end of the pulse tube refrigerator was studied in the following aspects:Firstly,the theoretical basis and advantages of numerical simulation are expounded.By analyzing and exploring the feasibility of simulation for studying the difference of internal flow of two heat exchangers and the evaluation standard of heat exchanger performance,the theoretical basis and realization approach of CFD numerical simulation are given.Secondly,an experimental system was developed to measure the fluid velocity distribution in the heat exchanger using Streamline Pro hot-wire anemometer.The flow and heat transfer mechanism in a hot end heat exchanger were studied on a 6W@90K removable pulse tube refrigerator.Thirdly,in view of two different structure of heat exchanger under the same conditions the same space coordinates of the speed of two sequential curve to carry on the numerical simulation and experimental measurement compared the velocity distribution of two kinds of heat exchanger,contrast analysis of the two kinds of heat exchanger in two specific point position of velocity temporal curve in numerical simulation and experimental measurement of differences,and analyze the possible causes of this difference;Simulation results and experiment results have verified the slit in the orifice plate heat exchanger heat exchanger compared with better heat transfer capacity and make the advantage of the fluid velocity distribution is more homogeneous,at the same time by experiment proved the accuracy of simulation results and the simulation method can helps for,for heat exchanger design and optimization model is established in this paper and the experimental verification method,which has important reference value.Finally,the paper points out the future work,as the complexity of the simulation model,the results of numerical simulation will be closer to the actual situation,at the same time,with the enlargement of the scope of application of hot wire anemometer condition and the development of the related theory,and the corresponding correction method of temperature calibration will be further development and improvement,the results will be more in line with the actual,experimental research will be more accurate.