Fabrication And Thermal Performance Experimental Study Of A Micro-Sintered Heat Pipe

With the rapid development of electronic technology, the problem of heat sink, which is caused by high frequency and speed of electronic apparatus, integration and miniaturization of integrated circuit, has become one of the basic factors that restrict the development of electronic technology. Therefore, the study of heat sink technology of electronic apparatus becomes more and more important. As a high efficiency means, heat pipe is being attached more and more importance for its small thermal resistance, excellent isothermal property, high reliability by electronic heat sink field.This paper started from another viewpoint, research on the capillary wick which is the core component of heat pipe. Try to improve the heat transfer efficiency of heat pipe through changing structure of the capillary wick. Sintered capillary wick is a kind of porous material; we produced multiple porous materials witch made from copper, aluminum and alumina firstly, then analyzed its microstructure and phase through SEM and XRD, tested the mechanics characters as well as Critical Bubbling Temperature of sintered samples at last.Based on those studies, we carried on the research on sintered capillary wick. Firstly, we designed the sintered heat pipe with multiple capillary wicks added with alumina fibre, then researched its heat transfer property.At last, the characters of heat pipe were tested through experiment. We researched the influencing factors on heat transfer coefficient on pipe's surface in boiling heat transfer, concreting heat transfer and thermal resistance, which contain the content of alumina fibre in sintered capillary wicks, the contend of reagent for making pores, the heating power to heat pipe and the angle for pipe.The experimental results show that: (1) pore-forming agent and alumina fibers changed composite porous materials'structure, reduced the critical bubbling temperuture and increased its porosity and decreased liquid's surface tension, so air bubbles spilled out more easily. Therefore porous materials that added with pore-forming agent and alumina fibers played a good role of heat transfer enhancement. (2) Evaporation heat transfer coefficient he and condensation heat transfer coefficient hc as well as heat pipe thermal resistance R were all greatly influenced by the concentration of the alumina fiber in sintered capillary wicks. he of heat pipe that with sintered wick containing 30% alumina fiber is 33% higher in average than that heat pipe with sintered wicks containing 20% fibers; hc is 14% higher in average; R decreased about 23 percent in average. (3) When the heat flux is low, NaCl content has a weak influence on he, hc and R; when the heat flux increases, he of heat pipe that with sintered wick added with 10% NaCl is 125% higher in average than that heat pipe with sintered wicks added no NaCl; hc is 82% higher in average; R dropped about 42% in average. (4) Evaporation heat transfer coefficient he and condensation heat transfer coefficient hc as well as heat pipe thermal resistance R were all greatly influenced by the tilt angle of heat pipe. The heat transfer coefficient of evaporation increased with the increases angle till the angle over 60°, and after that the heat transfer coefficient of evaporator decreased with the increasing of angle. The heat transfer coefficient of evaporator with the angle 60°raises 52% around in average to the one with 0°. hc increased with the increases angle. R decreased with the increases angle till the angle over 60°, and after that R increased with the increasing of angle. So R gets its minimum at the angle of 60°.