Design And Numerical Simulation Optimization Of Regenerative Phase Change Heat Exchanger

In recent years, with the rapid development of urbanization in our country,urban heating in winter has become important issues in people’s lives,the use of clean energy-- electrical energy for heating can reduce environmental pollution which caused by coal fired heating. The regenerative phase change heat exchanger has the characteristics of heat transfer and thermal storage, high heat storage density and high heat transfer efficiency, in addition, it has the function of power "peak cut" during using. So the study of regenerative heat exchange system and the heat exchanger has a great significance.In this paper, the research of regenerative phase change heat exchanger mainly includes the following aspects:(1)the indoor heating system is designed, in which the heat exchanger consists of a multi group phase change heat storage material with the same structure, and the heat storage process of the heat exchange tube is mainly studied.(2)Heat exchange tube is made of expansion graphite / paraffin composite phase change material, the heat exchange tube without metal shell and tube, directly achieve heat exchange and heat accumulation process.compare with traditional tube heat exchanger of heat exchange tube has more remarkable characteristics.In this paper mainly focuses on the design of the heat exchange tube structure, study the different structure size on the heat transfer process and the influence relations of the thermal efficiency, analysis of the process of thermal storage and heat storage capacity.(3) In the foundation of the basic structure of the heat exchange tube, simplifying the geometric model, established the physical model and mathematical model of the heat exchange tube, drawing and meshed by Gambit, using Fluent software for heat exchange tube of regenerative process numerical simulation.(4)Through analysis theresults of numerical simulation of heat exchange tube heat storage process,study the effect of different factors on the heat transfer pipe heat storage and heat storage efficiency, analysis of regenerative process in the basic rules,optimize the structure and thermal parameters of heat exchanger tubes, obtain the optimal structure and the optimal thermal parameters of heat exchanger tube.The results show that: Under the inlet parameters(inlet flow rate is 6m/s,inlet temperature is 353.15K), smooth tube heat exchanger regenerative time is 505 s, using concave finned tube regenerative time can reduce by 26 s, using convex finned tube type heat storage time can be reduced by 130 s.In the use of a tube inside concave fin structure of heat exchange tube, fin size choose height 3 mm, 2 mm width, spacing of12.13 mm, not only can reduce the heat storage time, the actual heat storage will be higher. Under the smooth heat exchange pipe structure, if the inlet temperature is343.15 K, the inlet flow rate is 8m/s, the heat storage time of the heat exchange tube is shorter, regenerative time is 418 s, the maximum heat storage capacity is 775.74 KJ.