Laboratory of Thermodynamics in Emerging Technologies, Department of Mechanical and Process Engineering, ETH Zürich, 8092 Zürich, Switzerland.
Nano Lett. 2012 Jul 11;12(7):3410-6. doi: 10.1021/nl300261r. Epub 2012 Jun 18.
The great majority of investigations of thermal transport in carbon nanotubes (CNTs) in the open literature focus on low heat fluxes, that is, in the regime of validity of the Fourier heat conduction law. In this paper, by performing nonequilibrium molecular dynamics simulations we investigated thermal transport in a single-walled CNT bridging two Si slabs under constant high heat flux. An anomalous wave-like kinetic energy profile was observed, and a previously unexplored, wave-dominated energy transport mechanism is identified for high heat fluxes in CNTs, originated from excited low frequency transverse acoustic waves. The transported energy, in terms of a one-dimensional low frequency mechanical wave, is quantified as a function of the total heat flux applied and is compared to the energy transported by traditional Fourier heat conduction. The results show that the low frequency wave actually overtakes traditional Fourier heat conduction and efficiently transports the energy at high heat flux. Our findings reveal an important new mechanism for high heat flux energy transport in low-dimensional nanostructures, such as one-dimensional (1-D) nanotubes and nanowires, which could be very relevant to high heat flux dissipation such as in micro/nanoelectronics applications.
绝大多数关于碳纳米管（CNT）热传输的研究都集中在低热通量上，也就是说，在傅立叶热传导定律的有效范围内。在本文中，我们通过进行非平衡分子动力学模拟，研究了在恒定高热通量下连接两个 Si 片的单壁 CNT 中的热传输。观察到异常的波状动能分布，并且为 CNT 中的高热通量确定了以前未探索过的、以波为主导的能量传输机制，该机制源于受激的低频横向声子。以一维低频机械波的形式，将传输的能量表示为施加的总热通量的函数，并与传统的傅立叶热传导传输的能量进行比较。结果表明，低频波实际上超越了传统的傅立叶热传导，并在高热通量下有效地传输能量。我们的发现揭示了低维纳米结构（例如一维（1-D）纳米管和纳米线）中高热通量能量传输的一个重要新机制，这对于微/纳米电子应用中的高热通量耗散可能非常重要。
