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

随着复杂的制造工艺为微型化提供了途径，纳米和微米级器件正变得越来越普遍。这些设备中的许多设备显示出与它们的宏观或中尺度对应物相同的物理行为，然而，随着尺度尺寸的减小，热传递可以显著不同。将探索三个不同的研究领域，以深入了解与纳米级传热相关的复杂问题。传热模型通常以无量纲组的形式表示，这些无量纲组将热力系统特性的逻辑组合联合收割机结合起来。通过保持组的整体大小，可以创建流体性质的变化导致刻度长度的类似变化的情况。实验将被设计为允许纳米尺度的特征长度被建模的工作与较大规模的尺寸，但在周围环境中，这是在一个降低的压力，从而允许传统的传热测量技术被用来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减小的尺度长度的综合效应。半导体器件和载流导线（例如形状记忆合金）依赖于电子流来完成电路，而热流通常通过电子-声子相互作用产生。将开发物理模型，使声子传输的振动特性与电子传输的定向流相结合。将实施一项实验计划，探索利用光刻技术和气相沉积形成50 - 100纳米量级温度传感器的热电偶结的发展。这些温度传感设备将被用来创建一个纳米级的温度探头，可以与扫描电子显微镜耦合，以测量纳米级设备的点源温度。

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.