Lattice Boltzmann simulation of droplet coalescence in fuel cell flow channel with mechanical vibration

Abstract

Fuel cells are the promising power source for future green vehicles and water management is an important issue for proton exchange membrane (PEM) fuel cells, which affects the lifetime and durability of fuel cells critically. In the available studies, the key parameters such as channel shape, airflow rate and material wettability have been extensively studied for water management. However, so far there is no open research on the effect of mechanical vibration on water management although most fuel cells work under vibration conditions. To bridge the knowledge gap, based on the Shan-Chen lattice Boltzmann model, this paper aims to reveal the water droplet coalescence process in an airflow channel under vibration conditions and several interesting observations are obtained for the first time. A large vibration amplitude or a small vibration frequency will not only hinder the movement of droplets, but also accelerate the coalescence of droplets. Also by comparing the simulation results it can be found that the droplet movement velocity decreases significantly after coalescence. Therefore, it is important to avoid large amplitude and small frequency for the operation of PEM fuel cells.