Research On Heat Transfee Performance Of Gravity Round Heat Pipe And Flat Heat Pipe

With the rapid development of economy,energy saving and efficient use are becoming more and more important.Heat pipe is one of the efficient heat transfer components based on the working fluids phase change mechanism,and has been applied in energy,aviation and other fields successfully.Round gravity heat pipe and flat heat pipe are widely used among them.This paper was based on the different application backgrounds of circular gravity heat pipe and flat heat pipe,the heat transfer performance of the two kinds of heat pipe were studied by experimental research.The heat transfer performance of gravity heat pipe was studied in different heating powers.The tests were conducted in different vacuum degree(1×10^-1Pa,1×10^-2Pa,1×10^-3Pa,1×10^-4Pa),filling ratio?15%,25%,35%,45%,55%,65%?,working fluid type?acetone,R113?.Besides,the length of circular gravity heat pipe and different widths,lengths and thicknesses of flat gravity heat pipe were studied.The results showed that the heat transfer performance of heat pipe increased with the degree of vacuum;before reaching the optimum heating power,the heat transfer performance of heat pipe increased with heating power;in this paper,the optimal filling rate of circular gravity heat pipe and flat heat pipe were 35%and 25%respectively.Besides,the liquid filling rate had a certain influence on the optimum heating power of heat pipe,the bigger the filling rate,the greater the optimum heating power;when the acetone as the working medium,the heat transfer performance is better than that of R113;under the same heating power,the longer the circular heat pipe,the better heat transfer performance;the wider the steam chamber cross-section of flat heat pipe,the higher the optimum heating power;the longer the length of the steam chamber of the flat plate heat pipe,the greater the thermal resistance,and the increase of length will increase the optimum heating power;the thicker the wall thickness,the worse the heat transfer performance of flat heat pipe.Finally,the experimental results of the flat gravity heat pipe and circular gravity heat pipe were compared.The width of flat heat pipe steam chamber cross-section was 4mm and the length was 150mm and the height was 200mm.The circular gravity heat pipe^'s internal diameter was 4mm and the height was 200mm.The results showed that the heat transfer coefficient of circular gravity heat pipe could reach 12000W/?m.k?and was much higher than that of flat heat pipe which was only 3600 W/?m.k?.As to the isothermal property,the circular gravity heat pipe was poor and the average temperature difference between evaporation section and condensation was about 8?,While the flat heat pipe was only about 2.5??...