Determination of heat-transfer coefficient in developing roadway with auxiliary ventilation

Heat-transfer coefficient on roadway surface is one of the most important parameters in the simulation of heat- and mass- transfer. Many methods have been put forward for determining the coefficient by theoretical analysis, model experiments or in-situ measurements, but most of the studies are made for the thermal environment prediction in an airway with through airflow. Because the air velocity near the wall surface changes greatly with the location in the heading face with auxiliary ventilation, the heat-transfer coefficients are position-dependent. Therefore, in order to predict the thermal environment in a working face with auxiliary ventilation properly it is necessary to develop a practical method to determine the distributions of heat-transfer coefficient there. The objective of the present paper is to develop a proper method for determining the heat-transfer coefficient in a locally ventilated working face. Firstly the principle of determining of heat-transfer coefficient in the working face with forcing auxiliary ventilation is discussed on the basis of the results of CFD simulation. Then, a direct relationship is established between the distribution of local heat-transfer coefficient on the rough surface of working face with that on the rough surface of corresponding through airway. Comparison is made between the results obtained from developed method and experimental results measured or calculated by others. The provided method in the paper can be used to calculate the values and distribution of heat-transfer coefficient on rough surface in working face.