Study On Performance Optimization Of The Underground Local Cooling System

With the increase of coal mining depth,the heat damage of the underground working face has become one of the main reasons restricting the deep mining.The underground local cooling system was widely used to solve the heat damage of the working face because of its advantages of short construction period,easy movement and low cost and so on,however it had the problem that the unit's lower performance(COP)in practical applications.In this paper,an optimized study of the underground local cooling system was carried out.The specific research contents and results were as follows:(1)The working principle and thermodynamic performance of the underground local cooling system were analyzed,and the reasons for the unit's lower performance were pointed out.Aiming at this problem,the underground local cooling system was optimized,and the thermodynamic performance of the optimized underground local cooling system was analyzed.The structure design of the air-cooled condenser and recooler in the optimized system was carried out,and the calculation method of the system refrigerant charge was given.(2)The simulation models of components in the optimized underground local cooling system and the physical parameters of refrigerant R134 a and air were established.MATLAB was used to establish the steady-state simulation model of the optimized underground local cooling system,the simulation results of the system under different compressor speeds,different condenser and evaporator air flow volumn,different recooler inlet water flow speeds and different system refrigerant charge were obtained,and the simulation results were analyzed.(3)FLUNET was used to conduct numerical simulation on the driving face.The distribution law of the temperature field of the driving face during side air supply and middle air supply,the temperature distribution changes of the tunneling working face under different supply temperatures during side supply air and middle supply air and the temperature distribution of roadway section after the driving face moves forward were studied,and it was concluded that the cooling effect of the driving face was better when the air was supplied in the middle than when the air was supplied in the side,the maximum outlet temperature of the duct was 22? when the air was supplied in the middle and the air duct should move forward with the driving face.