Simulation And Analysis Of Heat Transfer Characteristics Of Radial Heat Pipes

As an efficient heat transfer element,heat pipes are widely used in the fields of heatrecirculation,new energy development,aerospace,textile,production and life.As a kind of heat pipe,radial heat pipe has the characteristics of flexible arrangement,avoiding dew point corrosion and constant surface temperature.Radial heat pipes are often used in harsh engineering environments.In order to further optimize the structural design of radial heat pipe and study its heat transfer performance,it is necessary to make theoretical analysis and master its heat transfer characteristics on the basis of experimental research.The study of the radial heat pipe uses a combination of model calculations and numerical calculations to investigate its structure and heat transfer mechanism.Firstly,combining with the experimental results,the heat transfer process of the radial heat pipe is analyzed to establish the heat transfer resistance model of the heat pipe.The model was modified using experimental data.The nucleate boiling heat resistance is modified to obtain a calculation model which is in good agreement with the experimental data.Secondly,the model is used to calculate the influence of different operating parameters on heat transfer.The lower the inlet temperature of cooling water,the higher the temperature of peripheral flue gas,the greater the flow velocity of flue gas,and the larger the heat transfer.Increasing the mass flow of cooling water will increase the heat transfer of heat pipe.When the mass flow rate increases to a certain value,increasing mass flow has little effect on heat transfer.The influence of structural parameters on heat transfer was calculated by using the model.Increasing the diameter of the outer tube,decreasing the diameter of the inner tube and increasing the length of the heat pipe can increase the heat transfer.Thirdly,the filling rate of heat pipe is different and the filling state of the pipe is different.Heat transfer models of different liquid filling states were established to calculate the heat transfer of radial heat pipe under different liquid filling rates.The optimal liquid filling rate and maximum heat transfer were found.The optimal filling rate increases with the increase of inner tube diameter.The relationship between the best liquid filling rate and the ratio of inner tube diameter to outer tube diameter is obtained by fitting.Finally,based on the model calculation,a two-dimensional numerical model of the radial heat pipe was established to simulate the liquid filled heat pipe on the inner wall of the submerged part of the liquid pool,and the flow field in the pipe was simulated and analyzed.The simulation results show that the steam flow rate is the largest at the top of the adjacent liquid pool,and almost zero at the top of the heat pipe.The natural convection heat transfer between the liquid and the outer wall of the submerged inner tube is in a limited space.Nuclear boiling heat transfer occurs between the liquid working medium and the outer tube wall,and the velocity of the outer tube surface changes sharply.