CFD calculations of SOFC performance with bio-syngas

 

Introduction

A Solid oxide fuel cell (SOFC) is an electrochemical conversion device that produces electricity directly from fuel. Because of the high efficiency, low emission level of pollutants and the multi-fuel capability, SOFCs are considered to be environment-friendly devices for producing electricity. However, the development of the SOFC is challenging. Experiments to evaluate the performance of SOFCs are expensive and time-consuming; especially due to high operating temperatures (even the intermediate temperature SOFC operates above 650 ˚C). Hence is the importance of detailed simulation. Computational Fluid Dynamic (CFD) tools can be used to model the SOFC performance. Different geometries, different material specifications and the effects of variable operating conditions can be effectively optimized or analyzed through simulation before actual cells and stacks are designed. 

Economically viable conversion of biomass and agricultural residues requires highly efficient power plants.

The combination of biomass gasification systems with fuel cells is an attractive option, especially for small-scale decentralized power production. High temperature fuel cells like the solid oxide fuel cell (SOFC) provide better options for thermal integration, allow for carbon monoxide in the fuel gas stream and are capable of internal methane reforming. 

SOFCs are often designed considering a specific fuel, for example methane.  Different compositions of fuel streams will lead to changes in SOFC operation, such as the differences in gas distribution, current densities, heat production, temperature gradients etc, and maybe also to different life times for the fuel cells.

All these differences mentioned above would of course bring in new challenges to the materials and the structures for SOFCs.

Are the materials and the technologies available as of today good and suitable enough to satisfy the requirements? Or to say, are the changes still within acceptable limits? How does the SOFC performance change with different fuels? What kind of improvements could be made in terms of materials and structures before implementing these changes in real cells? The proposed assignment seeks to answer these questions. These evaluations will be carried out on SOFCs designed jointly by ECN and Delft University of Technology. ANSYS Fluent will be used to carry out the numerical investigation.

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Objective

The objective is to investigate the performance of SOFCs when fed with different fuels such as methane, biosyngas etc using CFD calculations and to come up with suggestions for efficient and ideal SOFC operation conditions when fed with different fuels.

Activities  

1.Literature review on the approaches and CFD modeling techniques of SOFCs. Repeat calculations from previous work to understand the model in depth and identify the real issues to be looked into.

2.Refinement of a three-dimensional model considering chemical and electrochemical reactions by introducing experimental data obtained from single cell test station.  Options to model electrochemical reactions as volumetric reactions will have to be investigated. Consistency in the usage of appropriate numerical schemes will also be studied. 

3.Investigate the cell performance and make comparisons between the cell performances when fed with different fuels with experimental data.