为了进一步提高微热管的传热性能,提出了一种新型的纤维复合沟槽毛细吸液芯结构,对外径为8mm、内部气体通道直径为4.5mm的纤维复合沟槽的烧结式微热管(GF)进行了实验研究,其中填充纤维的长度分别为2和5mm(对应的微热管分别记作GF2和GF5),并将GF与铜粉复合沟槽微热管(GA)进行对比.结果发现GF的传热性能更好:GF2和GF5吸液芯的平均孔隙率分别可达71.6%和76.3%,并能实现孔隙率的区域化分布;GF2的极限传热功率高达140W以上,输入功率为20~70W时,蒸发段、冷凝段热阻和总热阻都较低,分别稳定在0.04、0.03和0.07℃/w附近,具有很高的热传导率;输入功率为70w以上时,冷凝段及总热阻都有明显上升趋势,但总热阻仍比GA的低;热管蒸发段温度与蒸发段热阻关系较密切,而总热阻的变化趋势则与冷凝段的基本相同.
In order to improve the heat transfer performance of micro heat pipes, a new type of micro heat pipe (GF) with capillary wick, which is made of fiber-sintered grooves with an external diameter of 8 mm and an internal cavity diameter of 4.5 mm, was experimentally investigated. Then, the heat transfer performance of GF2 and GF5, namely two types of GF respectively with the filling fiber length of 2 and 5 mm, was compared with that of the composite heat pipe ( GA ) fabricated by copper powder. The results show that GF is of better heat transfer performance. For instance, the wick porosities of GF2 and GF5 locally distribute and the average values respectively reach 71.6% and 76.3%. The maximum heat transfer power of GF2 is more than 140W, and, with an input power of 20 -70 W, the evaporator, condenser and total thermal resistances are relatively low and keep unchanged respec- tively at about 0.04, 0.03 and 0.07 ℃/W. Moreover, with an input power of more than 70 W, both the condenser thermal resistance and the total thermal resistance obviously increase, and the total thermal resistance of GF is still lower than that of GA. It is also found that the evaporator temperature of heat pipe is closely related to the evapora- tor thermal resistance, and that the total thermal resistance varies in a trend similar to that of the condenser thermal resistance.