| In the daily production process of coal mine,wellhead anti-freezing is an important guarantee for safe production in winter.Wellhead ice will affect the normal operation of production equipment in coal mine,and even cause serious accidents.Traditional wellhead freeze-proof heat exchanger is a heating mode in which air is heated by high-temperature steam or hot water,and then hot air is fed into the well by a fan,that is,heat exchange between high-temperature steam or hot water and air.When there is a problem in the operation of the system,the hot water in the heat exchanger can not be discharged in time.If extreme weather occurs,it is easy to freeze and crack the copper tubes of the radiator.The safety accidents caused by the collapse of the heat exchanger pipeline due to the freezing of the retained water in the heat exchanger occur every year.Therefore,how to change the existing technology,mine shaft freeze-proof heat exchanger internal retained water caused by freezing radiator damage status,is the technical personnel in the field of urgent problems to be solved.In this paper,a new type of phase change gravity heat pipe heat exchanger is designed and manufactured.The heat exchanger absorbs hot water heat energy through phase change heat transfer of internal refrigerant,preheating fresh air of air supply well,so that the fresh air after heating can meet the needs of winter wellbore anti-freezing.By controlling the vacuum degree of the heat pipe,when the temperature of the hot water in the low-temperature circulation is lower than the setting temperature of the triggering anti-freezing ability,the refrigerant stops evaporating and stays in the evaporation section,and the heat transfer of the equipment stops.The condensing section is washed by the cold air,but because the inner part of the heat pipe is empty,the liquid will not be retained in it.The body is frozen,resulting in cracking of shell and tube,effectively prolonging the service life of the equipment.Through the experimental operation and data analysis of 12 cycles,the best refrigerant for heat pipe heat exchanger is R22.The optimum filling amount is 30%of the volume of heat pipe evaporation section,and the heat transfer coefficient is 293.96W/(m~2??).The recommended vacuum degree of antifreezing capability of heat pipe heat exchanger is also determined.The operating temperature of the different degree of vacuum corresponding to the heat pipe start-up antifreeze ability is different.When the heat pipe heat exchanger chooses R22 as refrigerant,the vacuum degree 16Kpa is recommended,and the starting temperature of the heat pipe should be 20.33?.When the operating temperature of the equipment is below 20.33?,the device automatically stops the heat transfer process and triggers the antifreeze function.In order to match the normal operation of the heat pipe heat exchanger and improve the market value of the equipment,a needle valve type heat pipe and a portable refrigerant filling device are designed and developed.The heat pipe can be repeatedly filled or replaced in the outdoor environment,and the refrigerant filling is controlled accurately,and the heat pipe is effectively maintained before and after filling.The vacuum inside the heat pipe is effectively maintained before and after filling.The equipment has been monitored in the Xingtai mine of Xingtai City,Hebei Province,and the operation result is good.In the coldest winter months,when the circulating hot water temperature of the evaporation section is below 20?,the condensing section stops heat transfer and starts the anti-freezing function.At this time,the monitoring value of the outdoor air temperature is-7?.After 24 hours of continuous shutdown,the heat pipe shell does not crack and can start up normally. |
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