双孔径分布毛细芯有效导热系数实验研究

Experimental study on effective thermal conductivity of bi-porous wick

对环路热管双孔径分布镍芯进行5因素4水平的16组正交化烧结实验研究,测量双孔径分布镍芯的孔隙率和有效导热系数,并与现有的11个多孔介质有效导热系数计算模型进行对比。从控制双孔径镍芯有效导热系数尽可能小的角度,得到由5个烧结参数的最佳水平组成的烧结工艺。结果表明：对双孔径分布镍芯的有效导热系数影响最大的烧结因素是造孔剂含量,其影响指数分别是压制压力和保温时间的1.9和2.2倍;烧结温度和造孔剂尺寸的影响度相当且较小;常用的估算环路热管金属烧结芯有效导热系数的Alexander模型的计算值偏高,Maxwell模型的计算值偏低,在孔隙率为0.5～0.7时,Chernysheva ＆ Maydanik模型与Chaudhary ＆ Bhandari模型计算值的平均值与双孔径分布镍芯的有效导热系数的实验值拟合更好。

Comprehensive effects of pore forming content, compacting pressure, holding time, sintering temperature and pore forming particle size on porosity, effective thermal conductivity （ ETC ） of saturated hi-porous nickel wicks, were studied through 16 groups of sintering experiments with five factors and four levels orthogonal design. The experimental results were compared with the calculated values from 11 ETC models of porous medium. The optimal level of five key sintering parameters was obtained from the point of making the ETC value as least as possible. The results show that the most important influencing parameter on the ETC of bi-porous nickel wick is the content of pore forming agent, whose impact factor is 1.9 times of compacting pressure and 2. 2 times of sintering holding time, respectively. The effect degrees of sintering temperature and the particle size of pore forming agent are similar and small. The calculated values based on Alexander model and Maxwell model, which are most commonly used models for the ETC estimate of loop heat pipe （LHP） porous wick, are overestimated and underestimated compared with the experimental values, respectively. In the porosity range of 0.5-0. 7, an average value based on the Chemysheva ＆ Maydanik model and the Chandhary ＆ Bhandari model can fit the experimental data best.