CFD Analysis of Turbulent Flow in Microchannels for Heat Exchanger Applications

Abstract

Microchannel (MC) heat exchangers (MCHXs) are tiny, lightweight, and capable of delivering 
superior Heat Transfer (HT) efficiency. A significant issue with MCHXs is the uneven dispersion of two-phase 
refrigeration from the Header Area (HA) into the MC tubing. This problem is widespread in evaporation 
programs' intake HAs, where two-phase condensate is supplied into the MCHX tubes. Recent advancements in 
multiple-phase flow Computational Fluid Dynamics (CFD) have enabled the visualization and analysis of 
intricate multiphase flow patterns inside the MCHX HAs. This article uses the Hybrid Eulerian Multiphase (EMP) 
framework to simulate condensate dispersion in a two-phase fluid simulation. This model integrates the 
advantages of the Traditional EMP model and the Volume of Fluid (VOF) approach, with the former identifying 
scattered phases and delineating phase separation surfaces. The simulation area is partitioned into three 
phases. Two environments use scattered phase simulation, where a single stage is distributed inside another 
and vice versa. The third phase utilizes a comprehensive interface methodology to distinguish between the two 
stages. This study discusses implementing the Mixed EMP technique, providing a thorough explanation of the 
generated CFD simulation, involving the sensitivity evaluation of the sub-models and variables. The model is 
confirmed empirically by infrared thermal imagery. The flow pattern is analyzed, and the factors contributing 
to the uneven distribution are discovered. Design research is conducted for two vertical HAs: a Tube-Insertion 
HAs and a Loop HAs, which incorporates a loop into the former kind. The Loop HA demonstrates enhanced 
distribution efficiency. A sensitivity study is conducted to comprehend the impact of characteristics essential 
for enhancing shipping, including tube-insertion dimension, intake mass flow rate, and HAs loop diameters. 
This work aims to provide an exhaustive simulation methodology for the Has’ uneven distribution issue in 
MCHXs.