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Air leakage in the goaf is a fundamental reason for the high-temperature heat damage of the coal mining face and the gas concentration in the upper corner exceeding the limit. Combined with the boundary layer theory, this study analyzes the airflow state of the coal mining face. We propose installing a new air curtain system to prevent air leakage in the goaf. The length of the intake air curtain is determined by solving the theoretical equation. Numerical simulation is used to study different layout schemes of air curtains, and the spatial distribution law of different air volumes inside the working face is analyzed. The simulation results are compared with the field-measured data. The results show that when the length of the air curtain on the air inlet side is 20 m, the wind flow on the working face can be approximated as a state of attached jet, and a diffuse turbulent flow area will be formed outside the air curtain. Gas concentration will increase in this area. The air leakage prevention effect is best when the air curtains with a length of 20 m for the inlet air and 10 m for the return air are arranged at both ends of the working face. This air curtain system can reduce the temperature of the working face and the gas concentration in the upper corner and has certain guiding significance for the air leakage prevention work in the goaf. [ABSTRACT FROM AUTHOR]

To solve the problem of unsatisfactory cooling effect of local cooling systems in coal mining faces, this paper constructs a simulation model of the working face, combines theoretical analysis and numerical analysis, and studies the influence law of four factors on the cooling effect in the cooling system (the combination of the air cooler C a , the air distance of the wind cylinder D a , the length of the wind cylinder L d and the air temperature of the air cooler T 0). The results show that when D a = 25 m, L d = 100 m, T 0 = 19 °C C 2 air cooler combination method, the average air temperature of the inlet roadway is reduced by 5.1 °C, the average air temperature of the working face is reduced by 3.8 °C, the average temperature of the return roadway is reduced by 2.4 °C, and 97 % of the area of the coal mining face is < 30 °C. Finally, the application was carried out at the site of 10303 working face, and the average temperature was reduced by 3.9 °C, the maximum air temperature dropped to below 26 °C, and the minimum temperature was as low as 24.3 °C. The thermal environment of the coal mining face was effectively improved, and the cooling effect of the cooling system was substantially improved. • Determined the optimal air cooler cooling parameters. • Analyzed the influence law of air cooler parameters on the cooling effect. • The cooling effect of the working face is greatly improved after application. • The temperature and humidity of the working surface are effectively reduced. [ABSTRACT FROM AUTHOR]

To solve the problem of high temperatures at the coal mining workings site. The CFD model of the coal mining face was optimized by importing user-defined functions (UDF) in ANSYS-Fluent and simulating the gas-liquid two-phase flow. By analyzing different ventilation variables, an air volume of 36.81 m3/s and an air temperature of 298 K were determined as the optimum ventilation parameters. Based on dynamic multi-field coupling analysis, a spray cooling system was proposed. The influence of water temperature, height, different zones, and spray group spacing on the cooling effect is analyzed by numerical simulation. The results show that the best effect is achieved when the water temperature is 286 K and the group spacing is 10 m. At this point, the peak temperature of a single group on the pavement side is 0.5–1 ℃ lower than the conventional temperature. The maximum temperature was 27 ℃, and the minimum temperature was 24.4 ℃. The effect of the system on cooling is even more pronounced during summer ventilation. [ABSTRACT FROM AUTHOR]