Analysis of Flow Rate Inducing Voltage Loss in a 100 cm<sup>2</sup> Class Molten Carbonate Fuel Cell

Lee, Choong-Gon

doi:2011.2.1.20

J. Electrochem. Sci. Technol > Volume 2(1); 2011 > Article

Article

Journal of Electrochemical Science and Technology 2011;2(1):20-25.
DOI: https://doi.org/10.5229/JECST.2011.2.1.020

Analysis of Flow Rate Inducing Voltage Loss in a 100 cm² Class Molten Carbonate Fuel Cell

Choong-Gon Lee

Department of Chemical Engineering, Hanbat National University;

Abstract

This work focuses on the behavior of the overpotential increase due to a utilization rise in a molten carbonate fuel cell. The behavior is generally explained by Nernst loss, which is a kind of voltage loss due to the thermodynamic potential gradients in a polarization state due to the concentration distribution of reactant species through the gas flow direction. The evaluation of Nernst loss is carried out with a traditional experimental method of constant gas utilization (CU). On the other hand, overpotential due to the gas-phase mass-transport resistance at the anode and cathode shows dependence on the utilization, which can be measured using the inert gas step addition (ISA) method. Since the Nernst loss is assumed to be due to the thermodynamic reasons, the voltage loss can be calculated by the Nernst equation, referred to as a simple calculation (SC) in this work. The three values of voltage loss due to CU, ISA, and SC are compared, showing that these values rise with increases in the utilization within acceptable deviations. When we consider that the anode and cathode reactions are significantly affected by the gas-phase mass transfer, the behavior strongly implies that the voltage loss is attributable not to thermodynamic reasons, namely Nernst loss, but to the kinetic reason of mass-transfer resistance in the gas phase.

Key Words: Molten carbonate fuel cell, Nernst loss, Overpotential, Mass transfer, Voltage loss