Cooling load and airflow distribution characteristics on mining face

To enhance the field applicability, based on enthalpy differences black box method was proposed to estimate the cooling load on mining face in this paper.The cooling load of mining face is composed of basic and increased cooling load. The former is considered with enthalpy difference between airflow in hottest period of summer and air flow under the cooling control at the target temperature, while the latter comes from the increased heat dissipation relative heat source after the implementation of cooling measures.Then taken above estimated results as a reference, theoretical analysis (i-d chart) and numerical simulation (Fluent software) were conducted on heat and moisture treatment process and distribution characteristics of air in tunnel after mixture cooling modes.The results show that the mixed air cooling process can be divided into three parts:cooling, mixing and warming, in which the most important is cooling process. Cooling process mainly depends on system refrigeration capacity and heat exchange equipment performance, which has great influence on the following two processes.During the mixing, air temperature (18℃~20℃ to 24℃~25℃,30℃~31℃ to 25℃~26℃) and wind speed (15~17 m/s to 1~2 m/s) change dramatically, showing a negative correlations between them.In addition, the length of mixing process should be controlled in less than 10 m (3~6 m) tunnel.At last, the warming stage should be reduced to release mining face heat and moisture source at the present stage, along with the system and parameter optimization, mine cooling should be made a scientific decision according to the concrete situation and diminish mine heat hazard during coal mining.