Study On The Heat And Mass Transfer Mechanism Of Porous Media And The Technology Of Heat Storage And Temperature Control In High-temperature Mine

Aiming at the downhole thermal damage caused by high-temperature surrounding rock,this paper proposes a heat storage and temperature control technology using phase change heat storage modules.The composite phase-change heat storage module designed in this paper is the core component of the temperature control technology.Through theoretical analysis,numerical simulation and downhole field testing combined research methods,the heat and mass transfer model of composite porous media is analyzed,and phase-change heat storage is established.The physical and mathematical models of the module are used to study the cooling conditions of the phase-change heat storage module designed in this paper,and combined with a mine in Pingdingshan to conduct field tests to simulate the cooling conditions in a high-temperature environment on site.The main conclusions are as follows:(1)Taking a 500 m roadway as an example,the wind temperature change curve of the roadway only under ventilation conditions is obtained through calculation,and the wind temperature exceeds the safety regulations;the numerical simulation is very close to the theoretical calculation value of the wind temperature curve,thus verifying the numerical simulation.reliability.(2)By comparing and analyzing the combined cooling measures of only ventilation and phase-change heat storage modules,the latter reduces the wind temperature at 500 m by 6.5?compared with the former,with a cooling rate of 20.02%,an average cooling rate of 3.73?,and an average cooling rate of 14.1%.At the same time,when phase-change heat storage modules are arranged along both sides of the roadway,the overall air temperature of the roadway is lower than 26°C,which complies with coal mine safety regulations and has a significant cooling effect.(3)Under the condition of constant inlet air temperature,with the increase of wall temperature,the greater the temperature difference between the surrounding rock and the air flow,the more heat will be absorbed,which shows that the greater the difference between the air temperature curves before and after cooling,the greater the cooling range.Also bigger.(4)Under the combined action of the ventilation and the phase-change heat storage module,along the ventilation direction,the roadway air temperature presents a "temperature block" distribution.The longer the ventilation distance,the more obvious the temperature distribution between the high and low sides in the middle.(5)The thickness of the phase change heat storage module affects the overall cooling effect.The results show that a phase change heat storage module with a thickness of 200 mm should be selected,which can increase the heat storage and achieve a better cooling effect.(6)Using numerical simulation to analyze the thermal environment of tunneling in a mine in Pingdingshan,combined with actual working conditions simulation to take joint cooling measures,it is concluded that the error between field measurement and numerical simulation is within 1?,and the effect is better.Analysis of the numerical simulation results shows that the temperature distribution at the same section of the roadway is uneven.Under the combined cooling condition,the overall temperature is lower than 26°C,and the cooling effect is significant.