Calculation Method Of Heat-transfer Coefficient In Working Face With Auxiliary Ventilation

With coal extractive depth increasing heat injury problem worsening. In order to effectively control heat injury would predict the distribution of mine thermal environment, but the air flow velocity distribution directly to affect the heat exchange between rock surface and air flow. Therefore, we must study on airflow temperature calculation in working face. Working face of local ventilation airflow and temperature calculations need to know the heading face of the heat transfer coefficient, also close relationship of heat-transfer coefficient and airflow velocity. Usually, the distribution of airflow velocity in working place is obtained with applying Fluent software to simulate the airflow.Wall functions are often applied to solve the turbulent airflow problem. Wall functions requires that first layer of nodes near the wall surface are located at the layer of logarithm law zone. Usually the mesh is grided so that distances from the first layer of nodes to the wall surface are equal. Because at working face with auxiliary ventilation the airflow distributes unevenly, it is impossible to put all of the first layer of nodes near the wall surface to the layer of logarithm law zone. The airflow field is simulated by using of a commercial software package under different meshing grids with various distances from wall to first layer of nodes. The method to determine the distance from wall surface to first layer of nodes is put forward. The distribution of temperature in working place with auxiliary ventilation is obtained to constant temperature condition. According to airflow and roadway with the heat exchange theory, combined with auxiliary ventilation airflow working face velocity distribution, has been distribution of working face dimensionless heat-transfer coefficient.