UC Irvine

ABSTRACT OF THE DISSERTATION

Two-phase Flow Dynamics in Two Parallel Thin Micro-channels

By

Jingtian Wu

Doctor of Philosophy in Mechanical and Aerospace Engineering

University of California, Irvine, 2020

Professor Yun Wang, Chair

Two-phase flow in micro-channels plays a critical role in micro-electro-mechanical systems, electronic cooling, chemical process engineering, medical and genetic engineering, bioengineering and etc. In PEM fuel cells, liquid water from humidified gas streams and electro-chemical reactions triggers two-phase flow in gas flow channels, which is one of the main reasons that reduce fuel cell performance and durability. The main goal of this thesis is to investigate two-phase flow dynamics in micro-channels at various superficial gas and liquid velocities and flow mal-distribution among multiple channels.

First, two phase flow in a single thin micro-channel is investigated to study the ranges of two-phase flow in the film flow regime, water fraction, and pressure drop using the Volume of Fluid (VOF) method which tracks the air-water interface in computation. The channel dimension is 164 mm by 3 mm by 0.3 mm. The numerical results are compared with experimental data, theoretical solutions and modeling data in terms of flow patterns, water fraction and pressure drop. The prediction indicates a film flow in the range of operation (1.69 m/s

Two-phase flow dynamics in parallel channels is then experimentally studied due to its significance in many engineering applications. A system of two parallel thin micro-channels with shared inlet and outlet manifolds is designed for this study with one channel subject to single phase flow and the other to two-phase one. The channel dimensions are the same as those in the VOF study with similar operating conditions including the superficial gas and liquid velocities, which are 0.86 m/s