1D thermodynamic modeling for a solid oxide fuel cell stack and parametric study for its optimal operating conditions. (1st April 2020)

• Record Type: Journal Article
• Authors: Min, Gyubin; Park, Young Joon; Hong, Jongsup
• Is Part Of: Energy conversion and management. Volume 209(2020)
• Publication Date: 2020-04-01
• Subjects: Solid oxide fuel cell -- Thermodynamic modeling -- Stack simulation -- Parametric study -- Performance map -- Optimal operation; Direct energy conversion -- Periodicals; Energy storage -- Periodicals; Energy transfer -- Periodicals; Énergie -- Conversion directe -- Périodiques; Direct energy conversion; Periodicals; 621.3105
• DOI: 10.1016/j.enconman.2020.112614
• Languages: English
• ISSNs: 0196-8904

Abstract

Highlights: An accurate, fast-calculating thermodynamic SOFC stack model is developed. The sole effect of each operating parameter and stack operating map are elucidated. High efficiency is obtained at low current density at an expense of power density. Fuel utilization above 0.4 enables high efficiency and residual heat utilization. Air utilization below 0.3 ensures stack stability with efficiency and power density. Abstract: Solid oxide fuel cell (SOFC) is regarded as one of the promising energy conversion technologies since it enables distributed power supply based on modularity and provides a high efficiency while emitting less CO2 than conventional power systems. In this sense, a number of SOFC systems have been studied actively aiming at high efficiency with various capacity, assisted by thermodynamic system analysis. However, previous SOFC stack models are not appropriate for the thermodynamic system analysis because those models use multi-dimensional simulation tools and require gross computational resources with excessive calculation time. Thus, in this study, an 1D model that employs analytical expressions with design values and properties measured from an in-house-fabricated SOFC for thermo-electrochemistry and resolves spatially a SOFC stack is developed by using C# to investigate its electrochemical and thermal behavior. The model is validated by using experimental data and is used to elucidate the effect of key operating conditions on thermo-electrochemical performance. A parametric study is conducted with respect to various operation variables such as current density, fuel utilization, air utilization, pressure, and steam to carbon ratio in order to estimate optimal SOFC operating conditions. Considering the effect of each parameter on the 1st law efficiency and outlet gas temperature, a performance map is derived as a function of current density, fuel utilization, and air utilization. To gain the efficiency higher than 50% and outlet gas temperature lower than 900℃, it is shown that the combination of a low current density, high fuel utilization, and low air utilization is necessary at an expense of power density and thermal energy. The results obtained in this study enables capturing optimal operating conditions of a SOFC stack without performing costly experiments.