小型平板CPL实现高热流密度散热的研究

针对小型平板毛细抽吸两相流体回路(CPL)在高热流密度下的特点,分析了不同工质时系统的压力损失与毛细芯的毛细抽吸力,得出采用氨工质有着较好的传热性能和更高的毛细限,同时得出影响系统毛细限的主要因素是蒸汽联管管径和工质的蒸气密度,提出了工质传输系数作为选取工质的重要指标。建立了蒸发器多孔芯,金属壁面以及工质气、液空间区域的耦合数学模型,并运用SIMPLE算法进行求解,得出蒸发器内的温度分布及由于侧壁效应对多孔芯传热传质与传热极限的影响,同时提出小型平板CPL系统存在侧壁效应传热极限,它是影响系统最大传热量的一个重要极限,在设计小型平板CPL必须予以考虑。

Investigation of Small-scale Flat-plate Type Capillary Pumped Loop for High Heat Flux Applications

The operational behavior of small-scale flat-plate type capillary pumped loop (CPL) at high heat fluxes was analyzed.The total pressure loss along the loop and maximum capillary pressure of the evaporator wick for different working fluids were obtained.The analysis results show that ammonia working fluid had better performance and higher capillary limit,and capillary limit was affected significantly by vapor line radius and working fluid density.The working fluid transmission coefficient was introduced as an important criterion for choosing working fluid.The numerical model of porous wick,metal wall and fluid region of CPL evaporator were established, and the entire evaporator is solved with SIMPLE algorithm as a conjugate problem.The numerical results are obtained and the effect of evaporator metal side wall conduction on the working limit of system is discussed.The side wall effect working limit existed in the small-scale flat-plate type CPL evaporator is introduced.The obtained results are useful for the design of small-scale flat-plate type CPL evaporator.