热电制冷的界面热-电输运特征及尺度效应的研究

Chip enhanced cooling is the key science and technology problem of national major strategic needs. Thermoelectric cooling is one of the best cooling method. While the temperature difference of thermoelectric cooling abruptly decreased from macro to micro, therefore it is very difficult to use in chip cooling. Although there is research shows that it may be caused by contact thermal and electrical resistance of diffusion barrier, but the mechanism is not clearly now. So we plan to firstly study the interfacial thermo-electric transport process of thermoelectric cooling. Then, we establish the molecular dynamics-Interface Element-Finite Element thermal physical model according to the heat transfer form(heat diffusion and heat wave), interfacial contact effect, the heat generation and transfer characteristic of chip, the multi-scale analysis method is used to study the thermos-electric transport character of the thermal diffusion barrier. The square wave electric source is used to drive the thermoelectric module, the effect of interfacial contact thermal resistance, electrical resistance and dimension on the cooling performance are analyzed, especially in the coupling region of interfacial contact effect and the change of heat transfer form. It presents the interfacial thermo-electric transport process characters and scale effect of thermoelectric cooling, and reveal the suddenly change mechanism of micro thermoelectric cooling. This study provides the theoretical support for solving the thermal management problem of chip cooling, and make up the study blank about interfacial thermo-electric transport process of thermoelectric cooling. It is very important for increasing the reliability and lifetime of military and aerospace devices.

芯片强化冷却是面向国家重大战略需求的关键科学技术问题，热电制冷是冷却芯片的有效方式之一。然而从宏观到微观过渡时热电制冷温差骤降，使其在芯片冷却应用中困难重重，虽有研究指出此现象可能是由热扩散势垒区的电阻和热阻引起的，但相关机理尚不清楚。申请人拟从热电制冷界面热-电输运过程着手，基于热传输形式(热扩散和热波)、界面接触效应和芯片产热传热特性，构建基于分子动力学-界面元-有限元的热物理模型，运用多尺度分析方法，研究热扩散势垒区的热-电输运特性；采用变频方波电源驱动热电模块，分析界面接触热阻、电阻和尺寸对热电制冷性能的影响，尤其是界面接触效应和热传输形式变化的耦合区间；阐述热电制冷的界面热-电输运特性及尺度效应，揭示微尺度热电制冷温差骤降的机理。该研究为解决芯片冷却问题提供理论支撑，填补热电制冷界面热-电输运过程的相关研究空白，对提升我国军事、航空航天领域等设备的可靠性和寿命有重要实际意义。

芯片内/芯片间增强冷却是国家重大战略需求的关键科学技术问题，而热电制冷是芯片冷却的最好方式之一，但因微型热电制冷器集成封装冷却芯片时制冷温差骤降，使得实际应用中困难巨大。如果能揭示热电制冷从宏观到微观过渡区间性能转变规律，那么就可以指导微型热电制冷器的设计，为解决芯片冷却问题提供理论支撑。基于上述背景，本项目展开了以下三部分研究内容：(1)基于声子、电子的Boltzmann输运方程，建立热电制冷的界面热-电输运模型，分析垫垒层厚度对界面边界热阻和电阻的影响，进一步探讨界面效应对热电制冷性能的影响；并自主设计搭建了热电制冷器物性测试台，修正物性参数，使模型精度控制在5%以内。(2)通过耦合Boltzmann热输运和傅里叶导热，引入器件热物性参数关联接触热阻/电阻和边界热阻/电阻，建立了微型热电制冷器的仿真模型，运用多尺度分析方法，研究电子、声子输运对器件热物性参数的影响，分析了界面效应和尺度效应对其内部温度分布、制冷温差、制冷量和COP的影响，优化设计的微型热电制冷器冷却通量可达300 W/cm2；基于界面效应引起的器件物性参数变化，提出了一种分段结构的热电制冷器，可将热电制冷温差、制冷量和COP分别提高151.8%, 103.4%, 71.0%。(3)采用数值和实验方法研究了微型热电制冷器冷却芯片及热点的特性，分析了微尺度下的脉冲过冷效应，探索了冷却高热流密度热点的能力，提出了一种微接触形式，进一步降低热点冷却温度；并制定和实施了热电冷却芯片的温控策略，提出了热电冷却芯片凝露问题的解决方案。