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

Three-dimensional multiphase flow computational fluid dynamics models for proton exchange membrane fuel cell: a theoretical development

A review of published three-dimensional, computational fluid dynamics models for proton exchange membrane fuel cells that accounts for multiphase flow is presented. The models can be categorized as models for transport phenomena, geometry or operating condition effects, and thermal effects. The influences of heat and water management on the fuel cell performance have been repeatedly addressed, and these still remain two central issues in proton exchange membrane fuel cell technology. The strengths and weaknesses of the models, the modelling assumptions, and the model validation are discussed. The salient numerical features of the models are examined, and an overview of the most commonly used computational fluid dynamic codes for the numerical modelling of proton exchange membrane fuel cells is given. Comprehensive three-dimensional multiphase flow computational fluid dynamic models accounting for the major transport phenomena inside a complete cell have been developed. However, it has been noted that more research is required to develop models that include among other things, the detailed composition and structure of the catalyst layers, the effects of water droplets movement in the gas flow channels, the consideration of phase change in both the anode and the cathode sides of the fuel cell, and dissolved water transport

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

Two-Phase Flows With Dynamic Contact Angle Effects For Fuel Cell Applications

Liquid water management is still a very critical challenge in the commercialization of proton exchange membrane fuel cell (PEMFC). Fundamental understanding of two-phase flow behaviors is of crucial importance to the investigation of water management issues. Recently, it has been noted that the dynamic contact angle (DCA) plays a critical role in the two-phase flow simulations and the conventional static contact angle (SCA) model has obvious limitations in the prediction of droplet behaviors. This thesis mainly focuses on the numerical modeling and simulation of two-phase flow problems with dynamic contact angle (DCA) and is presented by four papers. The first paper proposes and validates an advancing-and-receding DCA (AR-DCA) model that is able to predict both advancing and receding dynamic contact angles using Hoffman function (Chapter 2). In the second paper, the AR-DCA model is further applied to simulate droplet behaviors on inclined surfaces with different impact velocities, impact angles and droplet viscosities (Chapter 3). The third paper introduces a methodology to improve the evaluation method of contact line velocity in the AR-DCA model and an improved-AR-DCA (i-AR-DCA) model is developed (Chapter 4). The last paper presents different flow regimes in a single straight microchannel under various air and water inlet flow rates (Chapter 5)

Advancements in Polymer Electrolyte Fuel Cell Architecture and Performance using Electrochemical Modelling and Advanced Characterisations

With the ever depleting traditional energy sources and increasing the carbon footprints, the new landscape of the renewable energy sources has evolved. With the versatility of required environmental conditions, topological locations, operating temperature, polymer electrolyte fuel cells (PEFCs) operating on hydrogen has been recognised as a prominent renewable energy technology. PEFCs offers the possibility of zero-emission and high power density electricity generation for a wide range of transport, portable, and stationary power applications. While technology continues to improve, there are still some challenges concerning durability, cost and performance. An improved understanding of the processes occurring within operational fuel cells and optimisation of the cell architecture will accelerate large-scale commercialization of PEFCs. The most powerful ways to understand and resolve these challenges is to understand the complex interplay of the internal workings of fuel cells and cell design and architecture and operating conditions. Hence, the current research aims to analyse the advancements in the fuel cell design and architecture using a thermo-structural multiphase electrochemical modelling and the advanced characterisation techniques Firstly, the intricate relationship between cell compression and the flow-field architecture is established by determining the morphological factors using X-ray computed tomography (CT) techniques. The results provide insight into the complex interplay of the morphological factors deciding fuel cell performance and durability. Also, this study provides insight into the extent at which the morphological factors decide water and thermal management of the fuel cell, which are key issues to tackle to broad-scale commercialisation of the technology. Further, the multiphase non-isothermal two-dimensional numerical model was developed. The two-dimensional current, temperature and liquid water saturation profiles reveal the in-situ gradients and their correlations with the voltage decay with respect to an increase in cell compression. Finally, the effects of cell compression on the PEFC water dynamics were analysed using in-plane and through-plane in-operando neutron radiography. Neutron radiography provides a detailed understanding of what constitutes the thickness of liquid water present in the operating fuel cell. The Neutron radiography results were also used to validate the numerical models developed. Finally, this work also investigates the effect of secondary flow-field on the dead-ended anode performance and highlights the importance of the manufacturing and assembly tolerances on fuel cell efficiency. Collectively; this project delineates the comprehensive suite of characterisation techniques and numerical modelling to resolve the PEFC challenges and achieve the cell optimisation and durability required for wide-scale commercialisation of the technology

On the application of the PFEM to droplet dynamics modeling in fuel cells

The Particle Finite Element Method (PFEM) is used to develop a model to study two-phase flow in fuel cell gas channels. First, the PFEM is used to develop the model of free and sessile droplets. The droplet model is then coupled to an Eulerian, fixed-grid, model for the airflow. The resulting coupled PFEM-Eulerian algorithm is used to study droplet oscillations in an air flowand droplet growth in a lowtemperature fuel cell gas channel. Numerical results show good agreement with predicted frequencies of oscillation, contact angle, and deformation of injected droplets in gas channels. The PFEM-based approach provides a novel strategy to study droplet dynamics in fuel cells.Postprint (published version