A Cooling And Heat-Collecting System In Deep Mine Based On Direct Expansion Grounp-Coupled Heat Pump

The depletion of shallow resources and the increasing demand for energy have led to the inevitable trend of deep mining of mineral resources,and the problem of deep well heat harm has developed from certain phenomenon to general problem.Deep well thermal harm seriously endangers the physical and mental health of underground workers,accelerates the aging of electrical operation equipment,further induces wall rock softening and adsorption gas overflowing,resulting in the rise of mine safety accident rate.The harm has gradually become the fourth mine disaster after water,ash and gas.Deep well thermal harm and local high temperature is the result of many factors.The heat diffusion of wall rock is more than 40% of the total heat,which is the source of the problem,and with the deepening of mining depth,the proportion will increase significantly.Therefore,the heat hazard treatment of heat source primary factor-heat diffusion of wall rock is a problem worthy of studyIn order to reduce the heat diffusion of wall rock and improve the thermal environment of deep well,the paper takes the heat-adjusting layer of wall rock as the research object,and systematically study its heat diffusion mechanism and main heat sources,further presents a cooling and heat-collecting system in mine based on the principle of Direct Expansion Group-couple Heat Pump(DX-GCHP),who uses the DX-GCHP to collect heat within a certain range of the heat-adjusting layer of wall rock to dynamically block the heat diffusion of therock wall to the airflow,and adopts the laboratory test to study the operating conditions of the device and the cooling effect of the soil.The main research contents and conclusions are as follows:(1)Research on the heat diffusion mechanism of wall rock was conduct to determine the unsteady heat conduction calculation inside rock and the heat diffusion coefficient K of wall-airflow under different conditions,and then to master the heat diffusion law of roadway.By analyzing the heat diffusion of various heat source factors to determine the main causes of thermal harm in deep wells and to derive the calculation formula of cooling load on the working face by using the back analysis calculation method,which provides theoretical basis for taking targeted heat harm control measures;(2)By analyzing the working principle?advantages and disadvantages of the DX-GCHP to study the applicability of the application conditions and the feasibility of the technology of thermal harm treatment in deep well.The results showed that the construction conditions,resource conditions and systematic conditions of the DX-GCHP have good applicability in deep well,and the technology will show better energy performance in the treatment of deep well heat disaster;(3)Through the construction of column type of the DX-GCHP experimental system to study and analyze the operation conditions,soil cooling effect and main performance indexes of the device.The system performing results indicate that the temperature distribution in soil drops from 45~55 ? to 20~25 ? during room temperature(RT)of 29.1~34.3?,and the heat conduction mainly occurs in the horizontal direction.The hourly Energy Efficiency Ratio(EER),whose maximum value in the stage of cooling is 2.24 and the average is 1.64,is obviously higher than the theoretical value;the effective cooling radius of the device is 1.34m;The system performs efficiently and the effect is significant incooling.(4)The schematic diagram of the cooling effect of the thermostat after cooling accumulation shows: the DX-GCHP forms a dynamic thermal barrier layer within a certain range of the roadway the heat-adjusting layer by collecting geothermal energy.The layer blocks the heat conduction from rock to the roadway wall,reduces the tunnel wall temperature.The convective heat transfer process weakens with the difference between the wall temperature and the air flow temperature reducing.Even when the wall temperature is less than the airflow temperature,the wall rock changes from an exothermic body to an endothermic body,which has the effect of reducing the heat diffusion of the wall rock and dynamically regulating the thermal environment of the deep well,and provides a new method for comprehensive prevention and heat-harm control in deep mine.