Modelling of heat transfer processes in micro and nano-scale structures

随着先进的制造工艺为小型化提供了途径，纳米和微型设备正变得越来越普遍。许多这些设备显示相同的物理行为，他们的宏观或中尺度对应，然而，传热可以显着不同的尺度尺寸缩小。将探索三个不同的研究领域，以深入了解与纳米尺度传热相关的复杂问题。传热模型通常以无量纲群的形式呈现，这些群结合了热系统特征的逻辑组合。通过保持组的总体大小，可以创建一种情况，即流体性质的变化导致类似的尺度长度变化。实验的设计将允许纳米尺度的特征长度通过更大尺度的工作来建模，但在一个环境环境中，压力降低，从而允许传统的传热测量技术用于测量纳米尺度的条件。将开发分析模型来模拟电子-声子驱动的热传导在缩小尺度长度下的综合效应。半导体器件和载流导线，如形状记忆合金，依靠电子流来完成电路，而热流通常是通过电子-声子相互作用产生的。将建立物理模型，考虑声子输运的振动特性和电子输运的定向流动。我们将实施一项实验计划，利用光刻技术和气相沉积技术来探索热电偶结的发展，以形成50 - 100纳米的温度传感器。这些温度传感装置将用于制造纳米级温度探头，该探头可以与扫描电子显微镜相结合，以测量纳米级器件的点源温度。

Nano and microscale devices are becoming increasingly more prevalent as sophisticated manufacturing processes provide a pathway for miniaturization. Many of these devices display the same physical behaviour of their macro or meso-scale counterparts, however heat transfer can differ significantly as scale dimensions are reduced. Three distinct areas of research will be explored to provide insight into the complex issues associated with nanoscale heat transfer.1. Heat transfer models are often presented in the form of dimensionless groups that combine logical combinations of thermal system characteristics. By maintaining the overall magnitude of the groups, it is possible to create a situation where changes in fluid properties lead to analogous changes in scale length. Experiments will be designed that allow nanoscale characteristic lengths to be modeled by working with larger scale dimensions but in an ambient environment that is at a reduced pressure thereby allowing conventional heat transfer measurement techniques to be used to measure nano-scale conditions.2. Analytical models will be developed to simulate the combined effects of electron-phonon driven heat conduction at reduced scale lengths. Semi-conductor devices and current carrying wires, such as shape memory alloys, depend on electron flow to complete the electrical circuit while heat flows are typically generated through electron-phonon interactions. Physical models will be developed that allow for the vibrational characteristics of phonon transport in combination with the directional flow of electron transport.3. An experimental program will be implemented to explore the development of thermocouple junctions using lithographic techniques and vapour deposition to form temperature sensors in the order of 50 - 100 nano meters. These temperature sensing devices will be used to create a nanoscale temperature probe that can be coupled with a scanning electron microscope to measure point-source temperatures of nanoscale devices.