| In accordance with the development of renewable energy predicts,and in the context of low carbon and enhanced low-carbon,the share of coal consumption has declined,but it is still important in China’s energy structure for the coming decades.At present,the mining depth of coal mine is increasing,the number of thermal damage is also increasing,and the heat damage is restricting the development of the coal industry.High temperature mine heat damage management bases on the cooling load determination of high temperature coalface,and also determines the effect of thermal pollution governance.Reasonable and accurate calculation of the coalface cooling load and effective discussions of mine cooling technique is a key factor in the management of heat damage.At present,all the mine cooling load calculation methods fail to calculate the actual cooling load of coalface,and the calculation results are less than the actual value.The cooling of cold air in the mine also exists problems of insufficient cooling loads,and it is difficult to meet the underground cooling needs.This paper focuses on the heat transfer characteristics of surrounding rocks in coal mining face,and studies the theory of cold load calculation and the nonlinear wind temperature prediction in terms of fluid thermodynamics,heat transfer theory and CFD numerical simulation.This paper also establishes a regional cooling load calculation method of coalface including the discussions of the spray cooling technology.The main achievements and innovations of the paper are as follows:(1)This paper has analyzed the currently existing four kinds of cooling load calculation methods,which based on wind heat exchange mechanism of the surrounding rock and the commonly used linear wind temperature forecasting formula and the phenomenon of the poor management of mine heat damage.Heat transfer of surrounding rock is the main part of the cooling load of the mine,and through analysis,the Calculation results of the surrounding rock heat transfer with the condition of mean and linearized wind temperature is far less than the results with the non-linear wind temperature.(2)The nonlinear wind temperature formula is used to predict coalface wind temperature,and the length range of wind temperature below 30 ℃ is considered as a valid area for cooling.Using the idea,this paper establishes a regional cooling load calculation method through dividing the cooling area of the coalface.Regional cooling load calculation method is used to calculate mine cooling load,the maximum wind cold loads,and has analyzed the influences on the cooling load of the coalface with the condition of variable inlet air temperature,surrounding rock temperature,ventilation velocity,and received:①The coalface cooling load calculation results of the conventional calculation method is far less than that of regional cooling load calculation method,and the different heat transfer calculation results of the surrounding rocks is the main reason of different cooling load with different load calculation method.The maximum wind cooling loads is less than the real cooling load of coalface.In the mines where have heavy heat damage,cold air cooling can only satisfy the inlet area for the effective cooling section.②The cooling load on the coal face is basically the same,when the wind temperature ranges from 19 ℃ to 25 ℃,the cold wind inlet temperature have small influences on the coalface cooling load.③In terms of changing the temperature of the surrounding rocks,the coalface cooling load increases,when the temperature of the surrounding rocks increases.The relationship between the length of the cooling zone and the temperature of the surrounding rock is linearly decreasing.④Under the condition of the same wall temperature,the cooling load of different coalface increases with the increase of wind speed.And it’s almost linear,the relationship between the length of the cooling zone and the wind speed is linearly increasing.Wall temperature and wind speed increase,the length of the zone decrease in amplitude.Comprehensive analysis,under the condition of cooling air could achieve the cooling effect.The lower cooling wind speed should be adopted in different roadways,and the initial investment and the operating cost of refrigeration equipment can be reduced.(3)Under low Reynolds number conditions,the near wall treatment of turbulent flow bases on the heat transfer characteristics of the rock and the wind.Numerical simulation is carried out according to the regional cooling load calculation method in coal mining face area.The analysis of the theoretical calculation is obtained:①Numerical simulation and theoretical calculation are slightly different,but the overall results are more consistent.②In a short distance from the entrance,the heat effect of the surrounding rocks is small in the core area of the cold air,and the heat exchange heat is in line with the actual heat exchange.Through analysis,we can get the inlet temperature field which have calculated by Numerical simulation and theoretical calculation.(4)In general,cold airis adopted to reduce the temperaturethe of coalface.Air cooling load is limited,only solve the cooling requirements in a regional area,according to the idea of cooling in the area,the cooling solution is provided for the cooling quantity of air by water spray.Preliminary design and summary of the spray cooling scheme were carried out while analyzing the pros and cons of technology,the cooling system system is simple and reliable. |
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