Research On Thermal Performance Of A Novel Heat Pipe Used In Wellbore Antifreeze

When the mine is located in a cold and dry area,the temperature in winter is very low.When water accumulates inside the air inlet,it is easy for the air inlet to freeze,which brings inconvenience to the engineering transportation,and thus brings serious safety hazards to the safe production of workers and equipment under the mine.At present,the commonly used anti-freezing measures for wellbores use traditional coal-fired gas boilers,which use internally provided steam as a heat source for the anti-freezing of wellbores.However,this method has many building footprints,large investments,high energy consumption,large environmental pollution,and complicated management.Disadvantages.The constant temperature zone maintains a certain burial depth.The formation constant temperature zone has a stable geothermal potential.If the geothermal heat of the deep temperature zone of the mine is used for wellbore antifreeze,it is of great significance for energy saving and emission reduction.This paper innovatively proposes a new idea of using the geothermal energy of a constant temperature formation as the driving heat source of the heat pipe for the antifreeze of the wellbore.In conjunction with the calculation of the wellbore working conditions,an L-shaped gravity heat pipe is designed.The evaporation section is driven by the geothermal energy of the underground constant temperature layer.When the saturated evaporation temperature of the liquid working fluid is reached,a phase change occurs to generate steam.Under the effect of the temperature difference and pressure difference between the two ends of the heat pipe,the steam rises to the condensation section of the heat pipe and exchanges heat with the cold air of the wellbore in the condensation section.The heat pipe continuously guarantees the antifreeze requirement of the wellbore in winter by extracting the geothermal energy of the underground constant temperature layer.The physical model of the heat pipe is established.The VOF model is used to simulate the heat and mass exchange of the two-phase flow in the heat pipe.At the same time,the UDF is used to define the evaporation source item and the condensation source item in the heat pipe,and then the evaporation and condensation process of the liquid working medium is calculated.The evaporation and condensation processes of the liquid working fluid in the heat pipe at different times are analyzed by the gas-liquid two-phase volume fraction distribution,temperature field distribution,pressure field distribution and velocity field distribution obtained by the simulation software.Through numerical simulation,the temperature of the condensation end of the heat pipe can reach 275K,and the scheme of extracting the heat energy of the constant temperature layer by the heat pipe for the wellbore antifreeze is feasible.Optimize the structure of the heat pipe,and optimize the simulation of the heat pipe for the liquid filling rate,tube diameter,condensation section and insulation section length of the heat pipe evaporation section liquid pool.The results show that after the optimization of the heat pipe to extract the heat energy of the constant temperature layer,the temperature of the condensing end of the heat pipe is increased by 275.6K,and the optimized effect is ideal.At the same time,a structure-optimized heat pipe bundle design is proposed.This topic can provide a theoretical basis for the application of heat pipes in the prevention of wellbore antifreeze in geothermal mining,combining heat pipe technology with wellbore antifreeze research to solve practical production problems.