碳纳米管强化对流、辐射散热性能的机理及实验方案研究

The electronic chips continue to dimensionally scale down with the on-going increase of generated heat. The consequent generating heat could seriously influence the operating performance of related devices, and even damage themselves. More and more attention has been paid to the crucial issue of heat removal of integrated electronic industries. Taking account of the critical issues of the heat dissipating properties of electronic devices in the ground and the space environment, some novel strategies are developed to obviously enhance the heat dissipating properties of electronic devices based on the carbon nanotubes (CNTs) in this project. Firstly, the driving mechanisms and the optimal methods of the air convection driven by the thermoacoustic effect of CNT films are investigated, which could realize obvious enhancement of the convective heat dissipating properties with free-noise, low-consumption and without moving accessories. Secondly, the periodic CNT array structures will be designed and fabricated by the MEMS and the CVD method, and their radiation mechanisms will be clarified. Then the optimized structures of CNT arrays with low-absorption and high-radiation at typical wavelength would be obtained to obviously improve the radiative heat dissipation properties. Finally, the stability, the environmental suitability and the practicability of the CNT-based cooling devices would be tested to realize practical applications in the spacecraft and portable devices.

目前，电子器件的工作效率不断提高，随之产生的高密度热量不仅影响其工作效率，甚至还能决定其使用寿命，因此电子器件的散热冷却已经成为相关行业面临的重要难题。针对电子器件分别在地面环境和空间环境条件下面临的散热冷却核心难题，结合碳纳米管优越的热学性能，本项目将分别发展全新的空气对流散热和空间辐射散热性能强化方案，以实现电子器件对流、辐射散热性能的提升。首先，本项目将探索碳纳米管薄膜热声效应驱动空气流动的物理机制和最优化方案，进而在无运动部件、零噪音、低功耗条件下实现空气对流散热性能的明显提升。其次，利用MEMS技术和CVD法，我们将设计并制备周期性碳纳米管阵列微纳结构，阐明该微纳结构的红外光谱调控特性，获得在特定波长范围内低吸收、高辐射的碳纳米管材料，实现空间辐射散热性能的明显强化。最后，我们还将测试对流散热和辐射散热强化方案在特殊环境中的性能稳定性、环境适应性等要素，为其实际应用奠定基础。

本项目研究主要针对各类电子器件在不同环境条件下面临的散热冷却核心难题，结合碳纳米管优越的热学性能，分别开展了碳纳米管阵列和薄膜材料强化自然对流散热、空间热辐射散热、水蒸发散热和水蒸气冷凝散热性能研究。具体而言，首先开展了高定向碳纳米管薄膜的制备及热声电极研制，并且在碳纳米管薄膜热声电极两端施加了周期性高压脉冲，产生了明显的受热-冷却的气体驱动效应，实现了在无运动部件的情况实现了空气对流强化，可以使得碳纳米管薄膜的对流散热性能强化约13-17%。其次，详细开展了周期性碳纳米管阵列强化空间辐射散热性能物理机制研究，提出了硅基底上原位生长周期性“竹节”状碳纳米管阵列的方法，并详细研究了周期性“竹节”状碳纳米管阵列的导热和散热性能，完成了周期性碳纳米管阵列强化辐射散热元器件研制。更进一步，提出了采用多孔碳纳米管海绵材料强化水蒸发相变的新方法。采用该方法，水蒸发相变散热面积明显增加，温度均匀性明显提高，实现了水蒸发相变散热强化6.5-10.3倍。最后，我们还提出了采用碳纳米管网络结构表面强化水蒸气冷凝散热和液滴脱离性能，其冷凝传热效率相比紫铜基底表面提高了约36%。综上，本项目研究针对不同环境条件下的散热冷却问题，提出了空间辐射散热强化、空气对流散热强化和水相变散热强化新方法和新技术，为各类电子器件在不同环境条件下面临的散热冷却问题提供了有效解决方案，具有广泛应用前景。