Numerical Study On Thermotechnical Properties Of The CMR Pre-heater

The main combustible component of the Coal Mine ventilation air methane is a clean energy,but because of its low concentration(<1%),large concentration fluctuations,difficult to enrichment,the large amount of wind and other characteristics,it is difficult to directly use but direct discharged into the air.It is not only a waste of energy,but also a kind of pollution with the atmosphere,exacerbating the greenhouse effect.Currently the treatment of ventilation air methane technology include catalytic flow-reversal reactor、thermal flow-reversal reactor and preheated catalytic monolith reactor.The physical model of numerical study is based on the pre-heater of preheating catalytic oxidation device,which is developed by Shandong University of Technology Lab,and the plate of pre-heater is of two-way corrugated structure.Simplifying the plate-type CMR pre-heater physical model rationally,thermotechnical properties of the CMR Pre-heater was simulated by using the Fluent software.During the process of simulation,the SIMPLEC arithmetic and k-εturbulent model were adopted,and then the N-Sequation and energy equation were solved.In order to study the thermal characteristics of corrugated plate type ventilation air methane pre-heater,a plate type air pre-heater model was established as a contrast.Firstly,the effects of thermal characteristics on pre-heater of its internal air guide wall’s geometry were simulated study,the calculation results show that:The longer the air guide wall,the higher the heat transfer efficiency,the greater the resistance loss,but the increasing amplitude of the heat transfer efficiency is far less than that of the resistance loss.Considering the integrative function of the heat transfer efficiency and the resistance loss of air guide wall height of the air pre-heater,based on the simulation results,the reasonable length of air guide wall was scheduled as the half of the heat exchanger plate height.On the basis of this,according to the two types of ventilation air methane pre-heater,the influence law of their structural and operational parameters on the thermal performance were studied,getting the same conclusion:the distance between the plates unchanged,with the increasing of flow velocity,heat exchange efficiency reduced,and resistance loss increased;Under the same working conditions,the smaller of the distance between the plates,the higher of the heat transfer efficiency,and the greater of the resistance loss.Compared the calculation results of the two type pre-heater,the result show:under the same conditions,the heat exchange efficiency of the corrugated plate ventilation air methane pre-heater is higher than that of plate type air pre-heater,and the resistance loss is higher than that of the plate type air pre-heater resistance loss.So the integrated benefit of the corrugated plate type pre-heater is superior than that of the plate type air pre-heater.Finally,according to the corrugation geometric parameters of corrugated plate type pre-heater for further research.The wave parameters including wave’s wave parameters(wave height,pitch of waves)and longitudinal wave parameters(wave height,pitch of waves,the corrugated inclination angle).Calculation results indicate:the distance between the plates and the specified operation remain unchanged,that increasing corrugation height,heat transfer efficiency is higher,and resistance loss is bigger;That increasing the pitch of waves,heat transfer efficiency will be reduced,and the resistance loss will be reduced too;That increasing the corrugated inclination angle,heat transfer efficiency will be increased,and the resistance loss will increase.