Application of oscillations to intensify heat transfer in microchannel heat exchangers

应用振荡强化微通道换热器传热

• 批准号: 2595458
• 金额: --
• 依托单位: Newcastle University
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2021
• 资助国家: 英国
• 起止时间: 2021 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2595458
• 关键词: Application; oscillations; intensify; heat; transfer

Heat transfer remains an ongoing issue in electronics cooling applications. As these technologies continue to advance, and computer chips continue to shrink whilst becoming more powerful, there is a greater risk of overheating chips leading to faster device degradation and failure. One popular cooling method is to use microchannels containing a cooling fluid, microchannel heat exchangers (MCHX). However, whilst these microchannels provide some enhancement of the heat transfer rate due to the small diffusion length scales, the enhancement as a function of convective mixing is limited because the flows are typically restricted to the laminar flow regime. A potential solution to enhance mixing in these laminar flow ranges is to exploit fluid oscillations and the channel geometry to promote and enhance vortex generation similar to the oscillatory baffled reactor (OBR) and oscillatory helical reactor concepts (OHR). OBRs and OHRs achieve turbulent-like mixing through vortex formation either due to flow separation around baffles or through Dean vortex formation in curved flows. Importantly, in OBRs these vortices have been shown to enhance the heat transfer performance in laminar conditions. Whilst no comparable study has been performed in OHRs, it is reasonable to speculate that a similar heat transfer enhancement would result due to the similar flow structures. The similarities between the MCHX geometries and the OBR/OHR geometries are apparent. However, no one has yet considered applying the oscillatory flow concept to the MCHX geometries. With full flow reversal applied to the various geometries present in the literature, a wide range of next-generation MCHX coolers could be available.The research aims are as follows. Firstly, to examine vortex formation in milli/micro scale OBRs and OHRs. Secondly to quantify mixing enhancement in the microchannel designs. Finally, to intensify heat transfer using the oscillatory-MCHX designs. Theses aims will be achieved using the following techniques: brightfield micro particle image velocimetry, two fluid mixing index assessment, residence time distribution, chip heat transfer experiments, computational fluid dynamics aided heat transfer modelling/ optimisation and thermal particle velocimetry.

热传递仍然是电子冷却应用中的一个持续问题。随着这些技术的不断进步，计算机芯片在不断缩小的同时变得越来越强大，芯片过热导致设备更快退化和故障的风险也越来越大。一种流行的冷却方法是使用含有冷却流体的微通道，即微通道热交换器（MCHX）。然而，虽然这些微通道由于小的扩散长度尺度而提供了传热速率的一些增强，但是作为对流混合的函数的增强是有限的，因为流动通常被限制为层流状态。在这些层流范围内增强混合的潜在解决方案是利用流体振荡和通道几何形状来促进和增强类似于振荡折流板反应器（OBR）和振荡螺旋反应器概念（OHR）的涡流产生。OBR和OHR通过涡流的形成来实现类似湍流的混合，涡流的形成是由于挡板周围的流动分离或通过弯曲流动中的迪恩涡流的形成。重要的是，在OBR中，这些涡流已被证明可以增强层流条件下的传热性能。虽然在OHR中没有进行过类似的研究，但可以合理地推测，由于相似的流动结构，将导致类似的传热增强。MCHX几何结构和OBR/OHR几何结构之间的相似性是显而易见的。然而，还没有人考虑将振荡流概念应用于MCHX几何形状。通过将全逆流应用于文献中的各种几何形状，可以获得各种下一代MCHX冷却器。首先，研究了毫米/微米尺度OBR和OHR中的涡旋形成。第二，量化微通道设计中的混合增强。最后，为了强化传热，采用了蒸发器-MCHX设计。这些目标将使用以下技术实现：明场微观粒子图像测速，两种流体混合指数评估，停留时间分布，芯片传热实验，计算流体动力学辅助传热建模/优化和热粒子测速。