Design improvement of circular molten carbonate fuel cell stack through CFD Analysis

Abstract

Molten carbonate fuel cell (MCFC) is a promising technology for distributed power generation. The core of a MCFC power generation unit is the stack, where various fuel cells are connected together in series and parallel in order to obtain the desired voltage and power. Stack geometry and configuration are major engineering topics, as inhomogeneous temperature or mass fractions cause inefficient performances of the fuel cells, as efficiency and power smaller than the expected and shorter lifetime. A detailed model is a useful tool to improve stack performances, through design improvements. In this paper, a 3D model of a stack composed of 15 circular MCFC, considering heat, mass and current transfer as well as chemical and electrochemical reactions is presented. The model validation is conducted using some preliminary experimental data obtained for a MCFC stack developed in the Fabbricazioni Nucleari laboratories. These results are examined in order to improve the stack configuration. It is shown that power density may be increased of about 20% through double side feeding. In addition, the average temperature gradients in the axial direction are reduced of more than 70%. Significant reductions in the temperature gradients, especially in transversal direction, can be achieved by adjusting the mass flow rate of cathodic gas supplied to the various cells. NOMENCLATUREEffective diffusion coefficient (m 2 s -1 )Mass diffusion coefficient (m 2 s -1 ) Apparent activation energy (K -1 ) Faraday constant (96487 C mol -1 ) Specific enthalpy (J kg -1 ) M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 4 Viscosity (m s -2 ) Density (kg m -3 ) Electric conductivity (Ω -1 m -1 ) Tortuosity Mass fraction of species i

Modelling High‐Temperature Electrochemical Cells: An Engineering Perspective

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Three-dimensional modeling of polarization characteristics in molten carbonate fuel cells using peroxide and superoxide mechanisms

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Entropy Generation Minimization for the Optimal Design of the Fluid Distribution System in a Circular MCFC

“…Numerical independence analysis has been performed in (Verda and Sciacovelli, 2011).…”