Simulation Study On Heat Transfer And Resistance Characteristic Of Heat Pipe Heat Exchanger In Mine Return Air Source

Mine return air is a high quality and renewable energy source,especially these days,because of the contradiction between consumption and environment of non renewable energy is increasing,there are more and more research methods for efficient recovery of mine waste heat.The gravity type low temperature heat pipe heat exchanger system can technically achieve the utilization of this kind of low-temperature heat source.In this dissertation,the gravity heat pipe heat transfer system used in a coal mine in Shanxi Province is based on the numerical simulation and experiments.First of all,the basic theory of heat transfer in heat pipe heat exchanger and the fundamental mode of heat transfer is briefly introduced,the structure of heat exchanger is analyzed and calculated.In the existing theories,the calculation method of heat transfer and resistance applied to the system is summarized.Secondly,the economic analysis of the system is carried out.Combined with the engineering example,the system has been tested experimentally.The heat transfer,ventilation and condensate flow of the system are calculated,which reflects the operation of the system.The calculation shows that the system can complete the fresh air preheating independently.But the total latent heat of the return air side is almost 40 percent,with the increase of air volume and the increase of temperature difference between inlet and outlet,the volume of condensing water is also increasing.A layer of hydrophobic material is also proposed to reduce the effect of condensate on heat transfer of heat pipe.Subsequently,due to the limitations of experimental testing conditions,this thesis use the method of numerical simulation to examine the heat transfer and flow resistance performance.Because the symmetry of the flow field,the system can be simplified to some extent.The models are verified by experimental data and the error is about 25%.It can generally reflect the heat transfer and resistance characteristics of the actual system.The heat transfer and resistance changes of heat pipe heat exchangers under different flow rates are investigated.The change rule of heat transfer and resistance of heat pipe heat exchanger under different flow rates is explored by simulation and the results show that the heat transfer of the heat pipe exchanger increases with the increase of fluid velocity,but the rate of increase is more and more slow;The resistance of new and return air side of heat pipe heat exchanger increases with the increase of wind speed,and the increase speed is faster and faster.In order to achieve the purpose of improve the heat transfer performance,it is necessary to increase the wind speed properly,but the wind speed should not be too large,because the increase of air volume will also lead to the increase of pressure loss of heat exchanger,and the excessive pressure loss will reduce the overall performance of heat exchanger.Finally,the simulated operating data under different conditions are sorted out,and the heat transfer and resistance criterion equations suitable for the waste heat recovery system are fitted by linear regression method.In summary,this paper combines theory,measurement and numerical simulation methods to study the heat pipe heat exchanger system applied to mine return air waste heat recovery.The relevant research ideas and results have guiding significance for other engineering research methods.