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

As-Built 3D Heritage City Modelling to Support Numerical Structural Analysis: Application to the Assessment of an Archaeological Remain

Terrestrial laser scanning is a widely used technology to digitise archaeological, architectural and cultural heritage. This allows for modelling the assets’ real condition in comparison with traditional data acquisition methods. This paper, based on the case study of the basilica in the Baelo Claudia archaeological ensemble (Tarifa, Spain), justifies the need of accurate heritage modelling against excessively simplified approaches in order to support structural safety analysis. To do this, after validating the 3Dmeshing process frompoint cloud data, the semi-automatic digital reconstitution of the basilica columns is performed. Next, a geometric analysis is conducted to calculate the structural alterations of the columns. In order to determine the structural performance, focusing both on the accuracy and suitability of the geometric models, static and modal analyses are carried out by means of the finite element method (FEM) on three different models for the most unfavourable column in terms of structural damage: (1) as-built (2) simplified and (3) ideal model without deformations. Finally, the outcomes show that the as-built modelling enhances the conservation status analysis of the 3D heritage city (in terms of realistic compliance factor values), although further automation still needs to be implemented in the modelling process

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

Cooling Process Analysis of a 5-Drum System for Radioactive Waste Processing

A cooling system design for the processing of radioactive waste drums is investigated in this work, with the objective of providing insights for the determination of the air flow rate required to ensure an acceptable slag temperature (323 K or below) after 5 days. A methodology based on both 3D and 2D axisymmetric Computational Fluid Dynamics (CFD) modelling is developed. Transient temperature distributions within the drums in time and space determined by the heat transfer characteristics are studied in detail. A sensitivity analysis is also carried out assuming different physical properties of the radioactive slag. It was found out that for all variations analyzed, the maximum temperature of slag at the end of five days cooling is below 323 K, where the maximum outlet air temperature for a minimum air inlet velocity of 1 m/s is between 320 K and 323 K depending on the radioactive slag properties. When glass-like radioactive slag properties are assumed, the internal heat conduction within the slag is limiting the overall heat transfer, therefore requiring significantly longer cooling times

Experimental and numerical Investigation on the design of a bioinspired PEM fuel cell

Proton exchange membrane fuel cells (PEMFCs) are promising energy devices that directly convert chemical energy of fuels such as hydrogen to useful work with negligible environmental impact and high efficiency. The channel geometry of the Bipolar Plate (BP) has a considerably impact on the PEMFC performance. BP designs based on nature-inspired structures such as leaves, lungs or sponges have been explored to date with success but have not yet achieved their full potential. With the objective of researching new flow field designs with enhanced operation, this work presents an experimental analysis of a novel bioinspired design of the channels of a PEMFC. Starting from a CFD fluid flow analysis of different novel initial biomimetic designs, the most promising one was selected, manufactured and tested experimentally. Experimental results comprise polarization and power curves for a comprehensive set of operating conditions. Results were analysed and compared against a reference parallel-serpentine model. Results indicated that the proposed novel biomimetic design is particularly suited for improving water management at high reactants humidity reaching out a peak power a 6.0% higher in comparison with the reference design. Future research should further develop novel design variants and analyze water distribution within the channels

Experimental testing of multi-tubular reactor for hydrogen production and comparison with a thermal CFD model

AIP Conference Proceedings, 2033, Nov. 2018, Article number 130013-1-130013-9This study presents a comparison of the experimental tests and CFD results for a multi-tubular solar reactor for hydrogen production in a pilot plant in the Plataforma Solar de Almería. This paper describes the methodology used for the solar reactor design and the experimental tests carry out during the testing and characterization campaign of the plant. The CFD model which has been used to design the solar reactor has been validated with an error around 10%. CFD simulations also allow to solve the thermal balance in the reactor (cavity and tubes) and to calculate the percentage of reacting media inside the tubes which achieve the required temperature for the process. The temperature in the thermocouples is around 1200 °C for the experimental data and a 90% of the ferrite inside the tube is above 900 °C. The multi-tubular solar reactor, which has been design with CFD techniques, has been built and operated successfully.Ministerio de Ciencia e Innovación, Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica 2008-2011Fondo Europeo de Desarrollo Regional IPT-2011-1323-920000Fondos FEDER Andalucía 2007-2013 Proyecto RNM 612

On neural network modeling to maximize the power output of PEMFCs

Article number 136345Optimum operating conditions of a fuel cell will provide its maximum efficiency and the operating cost will be minimized. Thus, operation optimization of the fuel cell is essential. Neural networks can simulate systems without using simplifying assumptions. Therefore, the neural network can be used to simulate complex systems. This paper investigates the effects of important parameters, i.e., temperature, relative humidity in the cathode and anode, stoichiometry on the cathode and anode sides, on the po larization curve of a PEMFC (Proton Exchange Membrane Fuel Cell) having MPL (Micro Porous Layer) by ANN (artificial neural network). For this purpose, an analytical model validated using laboratory data is applied for prediction of the operating conditions providing maximum (and/or minimum) output power of a PEM fuel cell for arbitrary values of the current. The mean absolute relative error was calculated to 1.95%, indicating that the network results represented the laboratory data very accurately. The results show 23.6% and 28.9% increase of the power by the model and the network, respectively, when comparing the maximum and minimum power outputs

Data from Experimental Analysis of the Performance and Load Cycling of a Polymer Electrolyte Membrane Fuel Cell

Fuel cells are electrochemical devices that convert the chemical energy stored in fuels (hydrogen for polymer electrolyte membrane (PEM) fuel cells) directly into electricity with high e ciency. Fuel cells are already commercially used in di erent applications, and significant research e orts are being carried out to further improve their performance and durability and to reduce costs. Experimental testing of fuel cells is a fundamental research activity used to assess all the issues indicated above. The current work presents original data corresponding to the experimental analysis of the performance of a 50 cm2 PEM fuel cell, including experimental results from a load cycling dedicated test. The experimental data were acquired using a dedicated test bench following the harmonized testing protocols defined by the Joint Research Centre (JRC) of the European Commission for automotive applications. With the presented dataset, we aim to provide a transparent collection of experimental data from PEM fuel cell testing that can contribute to enhanced reusability for further research.Ministerio de Ciencia, Innovación y Universidades de España ENE2017-91159-EXPMinisterio de Economía y Competitividad UNSE15-CE296

Experimental Analysis of the Performance and Load Cycling of a Polymer Electrolyte Membrane Fuel Cell

In this work, a comprehensive experimental analysis on the performance of a 50 cm2 polymer electrolyte membrane (PEM) fuel cell is presented, including experimental results for a dedicated load cycling test. The harmonized testing protocols defined by the Joint Research Centre (JRC) of the European Commission for automotive applications were followed. With respect to a reference conditions representative of automotive applications, the impact of variations in the cell temperature, reactants pressure, and cathode stoichiometry was analyzed. The results showed that a higher temperature resulted in an increase in cell performance. A higher operating pressure also resulted in higher cell voltages. Higher cathode stoichiometry values negatively a ected the cell performance, as relatively dry air was supplied, thus promoting the dry-out of the cell. However, a too low stoichiometry caused a sudden drop in the cell voltage at higher current densities, and also caused significant cell voltage oscillations. No significant cell degradation was observed after the load cycling tests.Ministerio de Ciencia, Innovación y Universidades de España ENE2017-91159-EXPMinisterio de Economía y Competitividad UNSE15-CE296

Water liquid distribution in a bioinspired PEM fuel cell

This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)Water management is a key factor in the operation of hydrogen fuel cells since its formation may lead to significant mass transport losses, oxygen diffusion limitation and membrane durability issues. In this work, the effect of different operating conditions on the liquid water distribution inside a 50 cm2 active area bio-inspired PEM fuel cell has been studied. Therefore, a set of experiments was designed varying cell pressure, the reactants relative humidity (anode and cathode), temperature, and cell current density. Liquid water distribution for each operating condition was determined using neutron imaging technique as it has been proved to be an excellent technique for this purpose, including quantitative analysis and water profiles in the different areas of the bio-inspired flow field. The results show that high relative humidity of the inlet gas flows, high pressure, low temperatures and low current density favor the accumulation of water in the flow field channels and GDL. Specifically, water accumulates preferentially in the anode side that make contact with the low part of the cathode foams inserted in the flow field, instead of blocking the closest area to the gases outlets points