Modelling of Solid Oxide Fuel Cells Applied to the Analysis of Integrated Systems with Gas Turbines

Abstract

Solid oxide fuel cells (SOFCs), working at high temperatures with an incomplete fuel oxidation process, have become an interesting candidate for combination with conventional power generation technology, such as gas turbines, in order to develop power plants that are both functional and efficient. An absolute condition for successful analysis and optimisation of such plants is the existence of reliable simulation tools. Through this research, the goal of creating a method for mathematical simulation of SOFCs suitable for thermodynamic analysis of SOFC/gas turbine hybrid systems has been accomplished. The results is an integrated electrochemical and thermal steady-state model capable of simulating the operating behaviour of a fuel cell, i.e. gas utilisation, power produced, energy efficiency, and current and temperature profiles for different operating conditions. The model was based on the combination of work of leading authors within SOFC modelling. Improvements have been made at single-cell modelling level avoiding many of the assumptions made by earlier researchers who have addressed SOFC modelling in connection with system studies. The improvements are mainly in description of polarisation loss of the cell and also in the heat transfer modelling. The model developed is capable of simulating bipolar, planar cell geometry and also planar tube design. To verify the accuracy of the model predictions for the planar tube design, a comparison was made with single-cell test data from Rolls Royce. Agreement with the electrochemical results is within 2.5% when modelling three-cell modules. For larger twenty-cell modules good agreement was obtained at higher fuel flows. A possible explanation of the disagreement between the results at lower fuel flows and higher current densities could be the uncertainty in the data for the diffusion loss model. For the bipolar planar design a verification test showed good agreement with other models from the literature. Sensitivity studies have been performed elucidate the effect of different assumptions regarding input data, in particular electrochemical reaction and reforming rates, on calculation of the cell performance and on the conclusions drawn. The results showed that the variation in the empirical correlation factors used may lead to significant variations in the calculated temperature and current density distributions and, consequently, different cell performances. To gain a more accurate assessment of the performance of SOFCs, the application of more advanced three-dimensional SOFC models in system studies has also been discussed.

• author: Selimovic, Azra
• supervisor: [unknown] [unknown]
• opponent: Professor Selman, Robert, Illinois Institute of Technology, Chicago, USA
• organization: Thermal Power Engineering
• publishing date: 2002
• type: Thesis
• publication status: published
• subject: Energy Engineering
• keywords: statistical physics, plasma, plasmas, Gaser, fluiddynamik, Termisk teknik, termodynamik, Gases, fluid dynamics, applied thermodynamics, Thermal engineering, Hybrid Cycles, Gas Turbines, Mathematical Modelling, Electrochemistry, Fuel Cells, Solid Oxide Fuel Cells, thermodynamics, Matematisk och allmän teoretisk fysik, klassisk mekanik, kvantmekanik, relativitet, gravitation, statistisk fysik, Mathematical and general theoretical physics, classical mechanics, quantum mechanics, relativity
• pages: 130 pages
• defense location: M:B, Maskin, LTH, Lund
• defense date: 2002-04-23 10:15:00
• external identifiers: other:ISRN:LUTMDN/TMHP- - 02/1002- - SE
• language: English
• LU publication?: yes
• additional info: Article: 1. Integration of a Solid Oxide Fuel Cell into a Gas Turbine Process, A. Selimovic, J. Palsson,Sjunnesson, presented at the Fuel Cell Seminar, November 1998, Palm Springs, USA.2. Combined Solid Oxide Fuel Cell and Gas Turbine Systems for Efficient Power and HeatGeneration, J. Pålsson, A. Selimovic, L. Sjunnesson, Journal of Power Sources, Volume 86/1-2, pp. 442-448. March 2000.3. On-Design and Off-Design Performance Prediction for a Planar Solid Oxide Fuel Cell Stack, A. Selimovic, presented at The 4th European SOFC Forum. Lucerne, Switzerland, July 2000.4. Analysis and Effects of Heat Transfer and Friction Factor on SOFC Performance Characteristics,A. Selimovic, J. Yuan, M. Rokni, B. Sundén, J. Pålsson, T. Torisson, L. Sjunnesson, Presented at The 4th European SOFCForum, Lucerne, Switzerland, July 2000.5. Intermediate Temperature SOFCin Gas Turbine Cycles, J. Pålsson, A.Selimovic, P. Hendriksen, presented at ASME Turbo Expo, New Orleans, USA, June 2001.6. Networked Solid Oxide Fuel Cell Stacks combined with a Gas Turbine Cycle, A. Selimovic, J. Palsson, presented as poster at Grove Symposium, London, UK,September 2001. Submitted and accepted for publication in the Journal of Power Sources.7. Theoretical and ExperimentalEvaluation of a New Fuel Cell Concept: The Integrated Planar Solid Oxide Fuel Cell (IP-SOFC), P. Costamagna, A. Selimovic, R.Bozzo, G. Agnew, accepted for presentation at ISCRE 17, Hong Kong, August 2002. Submitted for publication in Chemical Engineering Science.
• id: bdc47e9a-2a46-4f81-af68-d49470281563 (old id 464489)
• date added to LUP: 2016-04-01 15:19:13
• date last changed: 2018-11-21 20:33:49