相变微胶囊功能流体内嵌通孔金属泡沫中流动传热特性基础研究

Thermal management system with high thermal efficiency is crucial to the thermal security of electronic devices in a closed aerospace craft. This project is aimed to propose a thermal management structure that open-celled metal foam is saturated with microencapsulated phase change material slurry(MPCMS), which is presumed as a breakthrough and alternative technique to traditional method with single PCM embedded in porous material. This technique essentially integrates the combined merits of high conductivity of metal foam and high fluidity and thermal storage of MPCMS. This study is expected to solve three critical problems of low conductivity of solid PCM, volume expansion in phase transition, high thermal resistance of base fluid in MPCMS. In this project, theoretical and experimental investigations will be performed on the flow and heat transfer mechanisms in MPCMS between base fluid and microencapsulated phase change material and in metal foam between MPCMS and porous matrix. In addition, the comprehensive physical and mathematical models for heat and mass transfer of MPCMS within metal foam will be developed. The influences of thermophysical properties of MPCMS and metal foam on flow and heat transfer will be explored. The present research is expected to provide experimental and theoretical foundations for the structure design and performance optimization of passive thermal management system for electronic devices in closed aerospace craft.

高效的热管理系统对密闭航天器内电子设备热安全具有重要意义。本项目突破现有的单一相变材料填充多孔介质的冷却方式，提出了相变微胶囊功能流体内嵌通孔金属泡沫被动式热管理结构，兼顾解决相变材料在固态区有效导热系数低、相变过程体积膨胀、微胶囊悬浮液在基液区传热热阻较大三个关键问题，有效地将金属泡沫高导热性与微胶囊悬浮液流体高潜热存储和流动性的优势相结合。本项目拟针对相变微胶囊颗粒和基液间流动换热以及微胶囊悬浮液在多孔材料内的耦合传热开展理论和实验研究，建立完整的金属多孔介质内相变微胶囊悬浮液流动传热数学物理模型，探索微胶囊颗粒和泡沫物性参数对金属泡沫内微胶囊悬浮液换热效率的影响规律。本项目的研究成果有望为密闭航天器内电子器件被动式冷却系统的设计和性能优化提供实验和理论基础。

高效的热管理系统对密闭航天器内电子设备热安全具有重要意义。本项目突破现有的单一相变材料填充多孔介质的冷却方式，将金属泡沫高导热性与微胶囊悬浮液流体高潜热存储和流动性的优势相结合，提出了相变微胶囊功能流体内嵌通孔金属泡沫被动式热管理方法，兼顾解决了传统相变材料导热系数低、过冷度高和体积变化的问题。项目通过实验详细研究了相变微胶囊颗粒以及纳米胶囊悬浮液在金属泡沫内的自然对流和相变传热特性，并通过实验首次量化了金属泡沫/相变材料间的非平衡传热特性，建立了考虑热非平衡效应的金属泡沫内相变微胶囊悬浮液传热模型。研究发现，添加金属泡沫后相变微胶囊颗粒和微胶囊悬浮液的换热效率分别提高了47%和38%；微胶囊颗粒的包覆材料抑制了内芯相变材料的自然对流，而相变胶囊悬浮液的自然对流可使换热效率强化26%，但由于黏度较高被金属泡沫孔隙所抑制；基于热非平衡效应的相变材料（微胶囊溶液、石蜡）与金属泡沫间的换热效率远高于经典文献中的预测值。本项目的研究成果有望为密闭航天器内电子器件被动式冷却系统的设计和性能优化提供实验和理论基础。