Study On Numerical Simulation Of Thermal Environment In Driving Face Of Heat Harm Mine

With the increase of mining depth and the improvement of mining mechanization,heat damage of deep well has become one of the most important problems in coal mine safety,the high temperature environment in mine underground affects the health of workers and production efficiency seriously.Therefore,it is of great significance to study the thermal environment of high temperature mine.In this paper,the thermal environment of the driving face is studied by means of theoretical analysis,numerical simulation,field test and so on,aiming at the 1304N driving face of the New Julong company.In this paper,the thermal diffusivity and thermal conductivity of coal rock are measured by experiments firstly;Based on the measured data,the convective heat transfer coefficient between surrounding rock and air flow,the heat transfer coefficient of air duct and unsteady heat transfer coefficient are obtained;The thermal environment parameters were measured,and the variation law of air flow enthalpy was obtained;Then,the mathematical model of the temperature distribution in the surrounding rock and the distribution of the air flow field are analyzed,the physical model is established,the temperature distribution of the surrounding rock and the thermal environment of the working face are simulated by FLUENT software,using air age and PMV-PPD index to evaluate the thermal environment of driving face.The influence of different factors on the thermal environment of the working face is analyzed by numerical simulation,and the temperature field?velocity field?air age and PMV-PPD distribution are compared under different conditions,according to the results of numerical simulation,a support vector machine(SVM)model based on particle swarm optimization(PSO)is established to predict the thermal environment of driving face;Then,based on the analysis of the heat source of the driving face,the calculation formula of the chilling requirement is derived by using the energy conservation,the relationship between the chilling requirement and the heat dissipation of the heat source is analyzed,calculating the chilling requirement of 1304N driving face is 580.5kW,based on the above,some reasonable suggestions are given for the rated refrigerating capacity selection of air cooler;According to the simulation of different air cooler installation position,the effect of cooling on the surface is analyzed.Research shows:The temperature field in the surrounding rock is affected by the air temperature and air amount,the temperature determines the amount of heat transfer and air amount determines the heat transfer capacity in a certain range;The temperature of air supply,air amount,and the distance between the head and air duct have certain influence on the thermal environment of the driving face,reducing the air temperature can effectively improve the thermal environment,increasing the air amount has limited impact on the thermal environment,and even have a negative effect of excessive increase,theoretically,the closer the distance between the head and air duct,the better the thermal environment of the driving face,considering the actual situation,5-8m is more appropriate;The prediction results of thermal environment based on SVM model show that the model has high prediction accuracy and fast operation,it is a scientific model and can be used to predict the thermal environment;One air cooler with 250kW refrigeration capacity is arranged at a distance from the driving face 350m-200m range,which can make the driving face have better cooling effect.