液态金属-电解液双流体的电磁驱动机理及其芯片散热问题研究

The study on the high-efficient heat dissipation technology is an important issue to be solved in modern electronic industry. Traditional heat dissipation methods including air cooling, water cooling, heat pipe cooling etc. still exist some shortcomings such as low cooling efficiency, large volume driven pump which are not suitable for portable devices, or cooling failure when the amount of heat dissipation exceeds the limit and so on. To better tackle such challenge, a method for designing liquid metal-electrolyte double fluid cooling system with compact structure, high heat transfer efficiency and practical value is proposed in the project. The double fluid is driven by electromagnetic force and utilized to remove cyclic the excessive heat of the chip. The main content of the project includes the research on electromagnetic driving effect of the double fluid, establishing the control condition of the double fluid in steady motion, designing the double fluid cooling system as well as the performance evaluation experiments, and studying on the heat transfer mechanism between the double fluid and the chip. The implementation of the project will provide a theoretical and experimental basis for the development of high performance chip cooling technology with liquid metal as the working medium.

研究高效的芯片散热技术是现代电子工业中亟需解决的重要问题，传统的散热方式如风冷、水冷、热管冷却等存在着冷却效率低下、驱动泵体积较大而不适用于便携设备或散热量超过极限后冷却失效等一系列缺点。为此，本项目提出一种设计结构紧凑、传热高效、极具实用价值的液态金属-电解液双流体散热装置的技术，该技术利用电磁力来驱动液态金属-电解液双流体，从而对芯片过高的热量进行循环搬运。项目的主要内容包括：研究双流体的电磁驱动效应，得到双流体平稳运动的控制条件，设计双流体散热系统并进行性能评估实验，揭示双流体与芯片之间的传热机制。本项目的顺利实施将为发展基于液态金属冷却工质的高性能芯片散热技术奠定理论和实验基础。

在目前所有可得到的流体材料中，液态金属是其中热导率最高的一类流体，这个特性使其成为大功率器件或高热流密度芯片散热中很有应用前景的冷却材料。在本项目中，我们研制了一种基于电磁驱动液态金属旋转流的散热系统，理论分析和数值模拟了液态金属的速度分布，结果显示，在纵切面上速度分布并不均匀，最大速度出现在正极附近。在散热系统的温度分布图上，电热片一侧的温度远高于其它区域，液态金属起的作用是使系统的温度均匀化。为了分析研究散热系统的散热性能，我们建立了一个二阶R-C热阻模型并确定了模型参数。通过实验发现，散热系统的总热阻随着加热功率的增加而呈现上升的趋势，并最终稳定在约4.42℃/W。除此之外，我们也通过实验测量了系统的热点温度-加热功率关系，关系曲线总体呈线性特征，斜率大约为1.033℃/W。有了这样的对应关系，如果知道了最大控制温度，我们就可以方便的确定最大可加热功率。本项目研制的散热方法给紧凑型冷却系统的设计提供了一种新的思路。