Heat-flux Theory And Simulation Study On Heat Damage Mechanism And The Airflow Properties At High Temperature Coalface

Coal is the main energy sources in our country.The proportion of production and consumption of primary energy in our country is about 76% and 69%.But more than 52% coal resource is in the depth of more than 1000m.Regular production could not be proceeded,while heat damage exists,if the depth is more than 800m.The exploitation of coal resource has turning to deep interior in our country,and about 92% of the production is in mine well.With the decreasing of the reserves of fleet coal bed and the increasing of the mechanization degree, heat damage becomes more and more serious.and influents the safety and high effeciency of coal production more and more heavily.Heat damage has become a significant issue needs to be solved.The hot environment with hign temperature and high humidity should be solved,in order to explore coal mine in deep interior.But the study on this area is still in the primary stage.There is no recognized theory system and effective instruction of technology and theory.Parameter measurement in coal mine,energetics and hydrokinetics analysis and CFD simulation are used to investigate the main heat sources,the mechanism of heat emanating, temperature forecasting of robbing working face,The characteristic of the flow field and the temperature field of robbing working face, and the optimization design of the cooling efficiency.The research results have guidance meaning for coal mine heat damage control. The main conclusions and innovate points of the study are as follows:(1) The mechanism of heat emanating and the distribution of heat sources were analyzed by thermodynamics and heat transfer theory.The results shows that heat from wall rock,machines and oxidation are the main heat sources in robbing working face.The amount of heat from wall rock and machines is more than 70% of all of the heat sources.(2) Heat from gob area was treated as three parts:heat from air leak,convection at the boundary and heat from oxidation.Resolution expression was represented for calculating the amount of heat emanating at robbing working face more precisely,based on seep mechanics and heat transfer theory.(3) The numerical solution model which coupled the flow field and the temperature field of robbing working face,and a single stagger grid arithmetic which is suitable for pipe flow as laneway were represented.The arithmetic is better than collocated grid method at precision and better than stagger grid method at programming and calculating time.(4) The CFD simulation results shows that,eddies were formed at the inlet corner and the outlet corner,so that the convection heat transfer time between air and the heat sources increased.The outlet corner came to be a local high temperature region,because of the large amount of heat emanated from the working face. The hot environment of robbing working face is heavily influenced by the inlet velocity.With the increase of the inlet velocity,the area of high temperature region in robbing working face reduced,and the temperature reduced linearity.There is a critical velocity of air.If the velocity is higher than the critical value, the heat environment could not be effectively improved by increasing inlet velocity.(5) The atomization cooling effect was forecased by multiphase theory.The simulation results shows that,if the quantity of cold water is steady,too big spray angle and diameter of the fogdrop would restrain the cooling efficiency.There is a critical value of the initial velocity of fogdrop.If the initial velocity is higher than the critical value,the cooling efficiency tends to be steady.The temperature of outlet increased in a power function with the accretion of the humidity of the airflow at inlet.(6) The initial thermodynamic parameters of fogdrop(velocity,diameter and spray angle) of the cooling project at robbing working face were optimized.After optimizing,the temperature of the outlet corner reduced about 5%.