Abstract
As a phase change evaporator, a microchannel array heat exchanger is of great significance in the field of microscale heat dissipation. The performance of which strongly depends on the flow resistance, capillary force, and other factors. In order to improve the heat dissipation efficiency, it is necessary to perform an in-depth study of the characteristics of microchannel flow using numerical simulation. However, the current simulation model requires high computational cost and long simulation time. To solve this problem, this paper simplifies the numerical simulation of the rectangular parallel array microchannels by building the basic flow model based on the concept of porous media. In addition, we explore the effect of aspect-ratio (AR), hydraulic diameter, inlet velocity, and other parameters of fluid flow behavior inside the microchannels. Meanwhile, a user-defined function (UDF) is formulated to add the capillary force into the model to introduce capillary force into the porous media model. Through the above research, the paper establishes the porous media model for single-phase and gas-liquid two-phase flow, which acts as a simplification of microchannel array simulation without grossly affecting the results obtained. In addition, we designed and manufactured experiments using silicon-based microchannel heat exchangers with different-ratios, and combined with the visualization method to measure the performance of the device and compared them with simulation results. The theoretical model is verified through the suction experiment of array microchannel evaporator capillary core. The simplified model of microchannel array significantly saves the computational cost and time, and provides guidance for the related experimental researches.
Highlights
The research shows that a flat heat pipe can reduce the temperature of the chip to the maximum extent, increase its overall temperature uniformity, and take very small heat dissipation space, which has significant advantages in high intensity heat dissipation and temperature control for micro-scale components [2]
Extensive research has focused on flat heat pipes (FHP) and vapor chambers (VC) [3]
The direction of liquid suction indicated by the arrow; (b) The physical model of two-phase flow of porous media is basically the same as that of microis indicated by the arrow; (b) The physical model of two-phase flow of porous media is basically the same as that of channels with the microchannels partially replaced by porous media
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. They formulated the theoretical model of fluid flow and heat transfer in micro heat pipe with diameter of 0.1–0.3 mm by using the method for porous media They studied a single capillary tube at millimeter scale, which cannot be directly applied to the array microchannels. This method used porous media model to capillary simulation, which greatly simplified the numerical modeling of array microchannels. One bottleneck issue in the numerical study is the high computational cost and long computing time for simulating the models with the large number of channels To solve this issue, the porous media method is applied to significantly simplify the model and save computational cost and time, without compromising the accuracy. The proposed model is simple and accurate, and useful to numerically simulate microchannel array, which can be used to design and understand experiments
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