Numerical Study on the Heat Transfer Performance of Non-Newtonian Fluid Flow in a Manifold Microchannel Heat Sink

Abstract

For the past few decades, with the rapid development of micro-electro-mechanical- systems (MEMS) and Lab-on-a-chip, the electronic devices continue to be miniaturized and highly integrated. Meanwhile, on account of miniaturization and integration, it essentially brings in high heat flux, which makes heat transfer enhancement to be a hot topic in these fields. With the heat flux rising, the traditional cooling method becomes unable to meet the demands of heat removal in the highly integrated devices. As one of the most promising heat exchange technologies with high efficiency, the microchannel heat sinks (MHS) was proposed. For a long time, modifying the microchannel structures is a promising way to enhance heat transfer, such as using manifold microchannel (MMC). Except modifying the microchannel structures, changing mediums in MHS could also contribute to better flow distribution and heat transfer performance. This paper concentrates on the synergy effect of non-Newtonian fluids and MMC heat sink on heat transfer enhancement. Numerical simulation of the non-Newtonian fluid in MMC is carried out in order to obtain its flow and heat transfer performance. The power-law non-Newtonian fluids are chosen as the cooling medium while water is a reference medium. The traditional microchannel (TMC) heat sink as an important reference model aims at evaluating the performance of the MMC heat sink through analyzing temperature distribution, power-law non-Newtonian fluids and so on. Numerical simulations are conducted for Newtonian and non-Newtonian fluid at a fixed heat flux on the heating wall. It is found that, in MMC heat sink, the non-Newtonian fluid characteristics could result in a significant variation in heat transfer coefficient with increasing inlet velocity. Moreover, the introduction of pseudoplastic fluid (shear-thinning fluid) leads to an outstanding increase of heat transfer performance comparing with those of Newtonian and dilatant fluids (shear-thickening fluid). Keywords: Manifold microchannel heat sinks; non-Newtonian fluids; heat transfer performance;