NER: Field-Aligned Nanotube Suspensions for the Active Control of Heat Transfer in Nanosystems

硅微电子等纳米器件的持续小型化可能会增加热管理技术的重要性。由悬浮在液体中的纳米颗粒或碳纳米管组成的纳米流体已经显示出增强热管理系统中使用的液体的热传输的前景。例如，碳纳米管悬浮液已被证明可以将基础液体的热导率提高高达2.5倍，体积分数仅为1%。迄今为止，对纳米管悬浮液的研究还没有利用碳纳米管的一个显著特性：热导率是各向异性的，并且沿着纳米管的轴沿着接近金刚石或石墨的热导率。通过将悬浮液中的碳纳米管与施加的电场对准，纳米流体有望显示出更大的热导率增强。此外，热导率将是各向异性的和可控的。通过改变悬浮的碳纳米管的取向与施加的电场，它应该是可能的主动控制导热性和热传递没有移动parts.Experiments提出了在液体悬浮液中对齐的纳米管的热性能。该研究的主要目的是证明定向碳纳米管的可行性，并表明热导率是各向异性和可控的。热通量将被测量为相对于温度梯度变化的碳纳米管取向的纳米流体。进一步的实验将试图测量热导率张量与纳米管取向和排列程度的关系。碳纳米管排列对热导率主动控制的可行性的证明将为下一代微处理器等纳米级系统的创新热管理策略打开大门。研究活动涉及研究生和本科生，并利用罗格斯大学纳米材料科学与工程（NMSE）计划的推广和课程开发工作。

Continued miniaturization of nanoscale devices like Si microelectronics is likely to increase the importance of thermal management technologies. Nanofluids, consisting of nanoparticles or carbon nanotubes suspended in liquids, have shown promise for enhancing the thermal transport of liquids used in thermal management systems. Carbon nanotube suspensions, for example, have been demonstrated to increase the thermal conductivity of base liquids by up to 2.5 x for a volume fraction of only 1%. Studies to date on nanotube suspensions have not exploited one of the remarkable properties of carbon nanotubes: the thermal conductivity is anisotropic and approaches that of diamond or graphite along the axis of the nanotube. By aligning carbon nanotubes in liquid suspension with an applied electric field, the nanofluid is expected to show even greater enhancement of thermal conductivity. Moreover, the thermal conductivity will be anisotropic and controllable. By changing the orientation of the suspended carbon nanotubes with an applied electric field, it should be possible to actively control thermal conductivity and heat transfer with no moving parts.Experiments are proposed on the thermal properties of aligned nanotubes in liquid suspension. The primary objectives of the proposed research are to demonstrate the feasibility of aligning carbon nanotubes, and to show that the thermal conductivity is anisotropic and controllable. Heat flux will be measured across the nanofluid for varying carbon-nanotube orientations relative to a temperature gradient. Further experiments will seek to measure the thermal conductivity tensor versus nanotubes orientation and degree of alignment.Demonstration of the feasibility of carbon-nanotube alignment for active control of thermal conductivity will open the door to innovative thermal management strategies for nanoscale systems such as next-generation microprocessors. The research activities involve graduate and undergraduate students, and also leverages the outreach and curriculum development efforts of the Nanomaterials Science and Engineering (NMSE) Initiative at Rutgers University.