Bipolar plate design of low temperature fuel cells by the assistance of computational fluid dynamics

Abstract: Proton Exchange Membrane Fuel Cell (PEMFC) is the low-temperature type of fuel cell that generates electrical power through the electrochemical reactions. Bipolar plates (BP) are the crucial component of PEMFC which provides the path for the transport of reactant gases to the whole active area of the Fuel Cell. Poor flow-field design can lead to non-even distribution of gas flow in the cell, which can result in reactants starvation at the local area of the active cell. In addition, the pressure drop of the fuel cell system is highly dependent on the BP design, specifically when multiple cells are sandwiched together in series in the stack. Therefore, obtaining optimal flow-field pattern would be necessary for optimal design at the cell level to increase the performance and reliability of the system at the stack level. Although numerical modelling and simulation via the computers made it possible to analyze the performance and reliability of fuel cell before any fabrication, or build and test, in reality detailed numerical calculation would be challenging and expensive. Therefore, this study focuses on 2D simulation with adopting engineering assumptions to analyze the reactant flow inside the BP at the cathode side, and various possible designs of BP with different flow-field patterns are simulated and analyzed. The details of the present study will be presented at the conference.Résumé de la communication présentée lors du congrès international tenu conjointement par Canadian Society for Mechanical Engineering (CSME) et Computational Fluid Dynamics Society of Canada (CFD Canada), à l’Université de Sherbrooke (Québec), du 28 au 31 mai 2023

Modeling and Simulation of APU Based on PEMFC for More Electric Aircraft

The current challenge in aviation is to reduce the impact on the environment by reducing fuel consumption and emissions, especially NOX. An open research direction to achieve these desideratums is the realization of new electric power sources based on nonpolluting fuels, a solution being constituted using fuel cells with H2. Reducing the impact on the environment is aimed at both onboard and aerodrome equipment. This paper proposes the simulation and analysis of an auxiliary power source APU based on a fuel cell. The auxiliary power source APU is a hybrid system based on a PEM-type fuel cell, a lithium-ion battery, and their associated converters. The paper presents theoretical models and numerical simulations for each component. The numerical simulation is performed in MATLAB/SimPower Sys. Particular attention is to the converter system that adapts the parameters of the energy sources to the requirements of the electricity consumers on board the MEA-type aircraft. Power management is performed by a controller based on fuzzy logic

A micro-structured 5kW complete fuel processor for iso-octane as hydrogen supply system for mobile auxiliary power units Part I. Development of autothermal reforming catalyst and reactor

A micro-structured autothermal reformer was developed for a fuel processing/fuel cell system running on iso-octane and designed for an electrical power output of 5kWel. The target application was an automotive auxiliary power unit (APU). The work covered both catalyst and reactor development. In fixed bed screening, nickel and rhodium were identified as the best candidates for autothermal reforming of gasoline. Under higher feed flow rates applied in microchannel testing, a catalyst formulation containing 1 wt.% Rh on alumina prepared by the sol–gel synthesis route proved to be stable at least in the medium term. This catalyst was introduced into the final prototype reactor designed to supply a 5kW fuel cell, which was based upon m cro-structured stainless steel foils. The reactor was optimised for equipartition of flows by numerical simulation. Testing in a pilot scale test rig, which was limited to a specified power equivalent of 3.5kWel, revealed more than 97% conversion of gasoline at 124 Ndm3/min total flow-rate of reformate, which corresponded to a WHSV of 316.5 Ndm3/(h gcat)

MIMO Hinf control for power source coordination - application to energy management systems of electric vehicles

International audienceThis paper deals with a control strategy used for designing energy management systems within average-power electric vehicles. The power supply system is composed of three sources, namely a fuel cell, a battery and an ultracapacitor - specialized within distinct frequency ranges - which must be coordinated in order to satisfy power demand of the vehicle's electrical motor. The three sources with their associated DC-DC converters are paralleled on a common DC-bus supplying the electrical motor. The DC-bus is required to be constant regardless of the load state thanks to the fuel cell which provides the mean power and to the other two sources - auxiliary sources - which are controlled to supply the high-frequency variations of power demand according to an H1 optimization strategy. MATLAB/ Simulink numerical simulation is used to validate the proposed strategy under real driving cycle condition proposed by IFSTTAR (Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux), and this approach is assessed against another optimal strategy that uses LQR as control design

Three-dimensional simulation of a new cooling strategy for proton exchange membrane fuel cell stack using a non-isothermal multiphase model

In this study, a new cooling strategy for a proton exchange membrane (PEM) fuel cell stack is investigated using a three-dimensional (3D) multiphase non-isothermal model. The new cooling strategy follows that of the Honda's Clarity design and further extends to a cooling unit every five cells in stacks. The stack consists of 5 fuel cells sharing the inlet and outlet manifolds for reactant gas flows. Each cell has 7-path serpentine flow fields with a counter-flow configuration arranged for hydrogen and air streams. The coolant flow fields are set at the two sides of the stack and are simplified as the convective heat transfer thermal boundary conditions. This study also compares two thermal boundary conditions, namely limited and infinite coolant flow rates, and their impacts on the distributions of oxygen, liquid water, current density and membrane hydration. The difference of local temperature between these two cooling conditions is as much as 6.9 K in the 5-cell stack, while it is only 1.7 K in a single cell. In addition, the increased vapor concentration at high temperature (and hence water saturation pressure) dilutes the oxygen content in the air flow, reducing local oxygen concentration. The higher temperature in the stack also causes low membrane hydration, and consequently poor cell performance and non-uniform current density distribution, as disclosed by the simulation. The work indicates the new cooling strategy can be optimized by increasing the heat transfer coefficient between the stack and coolant to mitigate local overheating and cell performance reduction

Biomimetic flow fields for proton exchange membrane fuel cells: A review of design trends

Bipolar Plate design is one of the most active research fields in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) development. Bipolar Plates are key components for ensuring an appropriate water management within the cell, preventing flooding and enhancing the cell operation at high current densities. This work presents a literature review covering bipolar plate designs based on nature or biological structures such as fractals, leaves or lungs. Biological inspiration comes from the fact that fluid distribution systems found in plants and animals such as leaves, blood vessels, or lungs perform their functions (mostly the same functions that are required for bipolar plates) with a remarkable efficiency, after millions of years of natural evolution. Such biomimetic designs have been explored to date with success, but it is generally acknowledged that biomimetic designs have not yet achieved their full potential. Many biomimetic designs have been derived using computer simulation tools, in particular Computational Fluid Dynamics (CFD) so that the use of CFD is included in the review. A detailed review including performance benchmarking, time line evolution, challenges and proposals, as well as manufacturing issues is discussed.Ministerio de Ciencia, Innovación y Universidades ENE2017-91159-EXPMinisterio de Economía y Competitividad UNSE15-CE296

CFD Applications in Energy Engineering Research and Simulation: An Introduction to Published Reviews

Computational Fluid Dynamics (CFD) has been firmly established as a fundamental discipline to advancing research on energy engineering. The major progresses achieved during the last two decades both on software modelling capabilities and hardware computing power have resulted in considerable and widespread CFD interest among scientist and engineers. Numerical modelling and simulation developments are increasingly contributing to the current state of the art in many energy engineering aspects, such as power generation, combustion, wind energy, concentrated solar power, hydro power, gas and steam turbines, fuel cells, and many others. This review intends to provide an overview of the CFD applications in energy and thermal engineering, as a presentation and background for the Special Issue “CFD Applications in Energy Engineering Research and Simulation” published by Processes in 2020. A brief introduction to the most significant reviews that have been published on the particular topics is provided. The objective is to provide an overview of the CFD applications in energy and thermal engineering, highlighting the review papers published on the different topics, so that readers can refer to the different review papers for a thorough revision of the state of the art and contributions into the particular field of interest

Algebraic observer design for PEM fuel cell system

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper, the concept of the algebraic observer is applied to Proton Exchange Membrane Fuel Cell (PEMFC) system. The aim of the proposed observer is to reconstruct the oxygen excess ratio through estimation of their relevant states in real time from the measurement of the supply manifold air pressure. A robust differentiation method is adopted to estimate in finite-time the time derivative of the supply manifold air pressure. Then, the relevant states are reconstructed based on the output-state inversion model. The objective is to minimize the use of extra sensors in order to reduce the costs and enhance the system accuracy. The performance of the proposed observer is analyzed through simulations considering measurement noise and different stack-current variations. The results show that the algebraic observer estimates in finite time and robustly the oxygen-excess ratio.Peer ReviewedPostprint (author's final draft

MULTI-SPECIES MULTI-PHYSICS MODELING AND VALIDATION OF HYDRODYNAMIC ELECTROCHEMICAL SYSTEM FOR USED NUCLEAR FUEL

Department of Nuclear EngineeringAccurate predictions of processes in hydrodynamic electrochemical systems require an understanding of both the surface electrochemical reactions and the bulk mass transport. Complete coupling of electrochemistry and fluid mechanics is computationally very rich for multidimensional modeling since it involves multiple components across multi-phases at the same time. Therefore, this study develops a computational model that combines a 3D model for calculating single-species mass transport and a 2D model for calculating multi-species electrochemical reactions. The computational model is validated against lab-scale experimental data using a rotating cylinder solid metal cathode and liquid metal anode in the Argonne National Laboratory. The 3D model assumes that U, the representative component in the system, dominates the hydrodynamic behavior, and thus calculates mass transport caused by the rotating solid cylinder electrode. The 2D model still reflects the diffusion of U, Pu, and Nd within a diffusion boundary layer and the bulk concentration changes of these components. The 3D model provides a diffusion layer thickness reflecting convective mass transfer effects to the 2D model. The results of the proposed model show good agreement with the reference experiment, and the model can be considered an important tool for investigating the multidimensional distributions of hydrodynamic and electrochemical variables.clos