Numerical Simulation of an Internal Reforming Solid Oxide Fuel Cell Unit Fueled with Hydrogen-Natural Gas Mixtures

Abstract

Blending hydrogen into natural gas grid can effectively reduce carbon emissions and promote the development of the hydrogen economy. Utilizing hydrogen-natural gas mixtures through internal reforming solid oxide fuel cells (SOFCs) can convert the chemical energy of the fuels direct into electricity, which is a promising technology for combined heat and power systems. In this study, a three-dimensional model for an internal reforming solid oxide fuel cell unit is developed coupling chemical and electrochemical reactions, mass, momentum and heat transfer processes. The influences of the hydrogen addition on the distributions of temperature, gas compositions, and current density are studied by changing the hydrogen ratios in the inlet gas mixtures. The simulation results show that the addition of hydrogen affects the coupling of the endothermic reforming reactions and exothermic electrochemical reactions, which leads to improved temperature uniformity and lower fuel utilization of the SOFC unit compared with pure methane feeding. In order to further enhance the heat transfer between the exothermic and endothermic regions, a heat-pipe enhanced interconnect is introduced in the model. The introduction of the heat pipe is demonstrated to have the ability to decrease the temperature gradient and increase the electrochemical performance.