Analysis of heat transfer and flow characteristics of composite wicks of loop heat pipes
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摘要: 环路热管是目前航天器热控制领域最前沿的热控技术之一,而高性能的毛细芯是其高效可靠运行的保证.为不断提升毛细芯的综合性能,目前毛细芯由单一结构向着复合结构发展.建立了圆柱型蒸发器环路热管应用的双层复合结构毛细芯的数学模型,对其传热与流动特性进行了分析,重点考察了热载荷以及复合芯内外层厚度比的影响,并同单一结构的毛细芯进行了比较.分析结果表明:复合芯在获得高的毛细抽吸力和蒸发效率的同时,可实现低的流通阻力与径向热导,其传热与压降特性明显优于单层芯,是高性能毛细芯的发展趋势;当复合芯的整体尺寸一定时,复合芯内外层的厚度比越大,复合芯的径向热导和流通阻力越小,有利于提高环路热管的运行性能.Abstract: Loop heat pipe is one of the most advanced thermal control devices in the spacecraft thermal control system, whereas high quality wicks are the key components for its efficient and reliable operation. To improve the overall performance of the wicks, composite wicks are the developing trend. The mathematical model of the two-layer composite wicks applied in loop heat pipes with a cylindrical evaporator was established, and its heat transfer and flow characteristics especially the effect of the applied heat loads and ratio of the inner and outer layer wick thickness were analyzed. Meanwhile, the performance of the composite wick was compared with that of the single structure wick. The modeling results show that the composite wick can acquire not only high capillary forces and evaporation efficiency, but also low flow resistance and radial conductance, and its overall performance is far better than that of single structure wick. When the size of the composite wick is fixed, as the ratio of the inner and outer layer wick thickness increases, its radial conductance and flow resistance decrease, which contributes to the efficient operation of loop heat pipes.
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Key words:
- heat pipe /
- composite structure /
- heat transfer /
- pressure drop
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