Research On Heat Transfer Performance Of Heat Pipe Heat Exchanger For Waste Heat Recovery From Mine Return Air

Mine return air contains abundant low-temperature waste heat resources,which can be recycled efficiently and environmentally friendly by a variety of ways.And it can be used to preheat the fresh air in the mine to ensure the safety of underground operation.This dissertation mainly studies the heat transfer performance analysis of gravity type low temperature heat pipe heat exchange system which is used in waste heat recovery from mine return air.Combined with theory,experiment and simulation,the heat transfer performance of heat pipe heat transfer system is optimized from the aspects of pipe arrangement,temperature and wind speed.The economy analysis and operation test of the heat pipe system in the practical engineering were carried out.The results show that the heat pipe system has great advantages in economy,energy saving and environmental protection.During the test,the fresh air outlet temperature can meet the requirements of mine ventilation temperature,and the well head anti-freezing can be realized.The latent heat of the return wind accounted for about 42% of the total heat.Heat pipe system efficiency was 0.54.The heat pipe heat transfer effect is good.And temperature and wind speed have great influence on heat transfer of heat pipe.In order to facilitate maintenance and clean the heat pipe,the maintenance channel should be arranged in the system.Due to the limitation of actual engineering and measured conditions,Fluent software was used to simulate the heat pipe heat exchanger in this dissertation.In order to get closer to the engineering practice and reflect the heat transfer of heat pipe more accurately,UDF program was used to simulate the latent heat of phase change.By comparing the simulated data with the measured data,the model can be used to study the heat transfer law of the heat pipe system.Through model simulation analysis,the influence on the heat transfer performance of the system was studied from the aspects of pipe arrangement with access passage,fresh air inlet temperature and wind speed.The results show that from the perspective of piping arrangement,the optimal piping arrangement is 4/4/4,which has the best heat exchange,the largest heat exchange,the best effect of preheating fresh air and the highest efficiency,followed by 3/6/3 and 6/6.From the perspective of the inlet fresh air temperature,the lower the inlet fresh air temperature is,the greater the heat exchange is,but the outlet fresh air gets colder.It is easy to appear that it does not meet the preheating temperature requirements of fresh air.Considering from the aspect of wind speed,the higher the wind speed,the greater the heat exchange,but the increasing range is smaller and smal ler.And the fresh wind is warming less and less.It's getting harder and harder to warm up the fresh air.The efficiency is getting lower,and the pressure drop is getting higher.When the inlet temperature of fresh air is-20?,-15? and-10?,the working condition of 3.5m/s wind speed is optimal.For the purpose of fully efficient use of waste heat resources and lowering initial investment,the design of minimum fresh air inlet temperature is considered according to the proportion of meteorological temperature range.In a tiny part of cold weather,the electrically assisted heating module can be opened appropriately or the wind speed can be adjusted to make the temperature of the fresh air outlet meet the ventilation requirements.