Theoretical Modeling of methane production in pressurized micro-tubular R-SOFC

Abstract

Power-to-syngas using reversible solid oxide fuel cell (R-SOFC) can efficiently store intermittent renewable energy in the form of syngas. RSOC function in both solid oxide electrolysis cell (SOEC) mode for renewable energy storage and solid oxide fuel cell (SOFC) mode for converting syngas back to electricity. R-SOFC thus can be used as fuel cell or electrolysis cell depending on the renewable energy outputs and user loads. Pressurized R-SOFC is able to remarkably improve the cycle efficiency and reduce the system size.In this paper, pressurized high temperature R-SOFC reactor has been designed for the test of micro-tubular R-SOFC. Experiments have been performed in pressurized R-SOFC at 650 ℃ in the pressure range from 1 bar to 4 bar on a Ni-YSZ/ScSZ/LSM-ScSZ micro-tubular cell. A muti-scale and muti-physics two-dimensional (2D) micro-tubular R-SOFC model is developed. This model couples the electrochemical reaction, charge transfer, mass transfer, momentum transfer, heat transfer as well as the parameters of microscale porous electrodes. The experimental data obtained experimentally is used to validate this model. Therefore, the model is able to offer reliable guidance for the micro-tubular R-SOFC at various operating conditions. The effects of pressure on the cell performance and methane production has been discussed in detail. The methanation reaction rate distribution is discussed at pressure range from 1 bar to 4 bar. Competition between methanation reaction and electrolysis are found to control the methanation reaction rate distribution. Higher pressure are favored in methane synthesis, while electrolysis can further enhance the methane production process.