Optimisation of Electrochemical Flow and Transport Processes in PEM Fuel Cells using Direct Numerical Simulations.

Abstract

Optimisation of flow and transport processes in fuel cells using direct numerical simulations requires an understanding of the interaction between fluids and solid microstructures which govern the performance. Operating at high current density which is essential to reduce fuel cell costs, increases the rate of water production and accumulation (flooding). Therefore, understanding the key mechanisms of water appearance and distribution is essential for optimisation through designed materials. This work first focused on computational simulations to investigate the effect of designed and conventional gas diffusion layer (GDL) microstructures on the effective transport properties (effective electrical conductivity and permeability) and management of water (two-phase flow). This work emphasised that designed microstructures, through additive manufacturing can improve these properties. Next, volume of fluid (VoF) simulations was used in X-ray computed tomography images of different commercial GDL to study the effect of water cluster dynamics in the GDL and at the interface with the gas channel. Understanding the limitations of VoF, a discrete particle model was developed to simulate two-phase flow in gas channels, at large temporal and spatial scales, which elucidated the role of the GDL and channel conditions for development of performance critical two-phase flow regimes (plug and film flow).

Date of Award	1 Aug 2021
Original language	English
Awarding Institution	The University of Manchester
Supervisor	Stuart Holmes (Supervisor) & Vahid Joekar-Niasar (Supervisor)