Abstract:

In order to optimize the structure of sintered powder wick and improve the thermal conductivity and effi-ciency of heat pipes,the heat transfer characteristics of the sintered heat pipes with the outer diameters of 5,6 and8 mm and with a wick thickness ranging from 0.5 to 0.6 mm are discusse. The resuhs show that,when the copper particle size distribution is concentrated,both the porosity of the wick and the maximum heat transfer power (MHTP)of the heat pipe increase with the average particle size,while the temperature difference at the condensa-tion end and the total thermal resistance both slightly decreases,and that,when the particles in different sizes are mixed,the variation rules of the temperature difference at the condensation end and the total thermal resistance are different for heat pipes with different outer diameters. Moreover,it is found that the MHTP of the heat pipe decrea-ses with the copper particle size and reaches the minimum when the pipe is sintered with 70% of small-size parti-cles,that the MHTP of the heat pipe sintered with 70% of large-size particles is only second to that of the pipe sintered entirely with large-size particles,that a more concentrated particle size favors the perform ance of the heat pipe,and that copper powders with an average particle size of(165±15)Ixm is appropriate to the manufacturing of heat pipes.

Key words: heat pipe, heat transfer performance, copper powder, porosity, particle size, therm al resistance