Comparison of equilibrium-based and kinetics-based models for evaluating the impact of hydrogen carrier reforming on SOFC system

Abstract

This paper evaluates the computational risks of using Equilibrium-Based Models (EBMs) and Kinetics-Based Models (KBMs) interchangeably for simulating the external reformer in Solid Oxide Fuel Cell (SOFC) Balance of Plant (BoP). Various reforming processes, including steam reforming, partial oxidation, and autothermal reforming of hydrocarbons are assessed. The study systematically investigates the effect of reformers operating parameters, such as temperature, pressure, steam-to-carbon ratio, and oxygen-to-carbon ratio, on SOFC performance captured by EBM and KBM. In contrast to EBM, the KBM consistently provided a more detailed and accurate measures of system behaviour. This is more evident, especially under conditions where reaction kinetics play a crucial role, such as in high-pressure scenarios or significant variations in the steam-to-carbon ratio. The KBM captured the details of reaction kinetics and mass transfer limitations that the EBM, with its inherent assumption of near-instantaneous equilibrium, could not fully replicate. While EBM is computationally effective for minimising modelling complexity/time at the system level, it has limitations in scenarios that require detailed reaction kinetics due to the nature of reaction or fuel mixture. EBM and KBM results deviations are quantified to identify regions where these risks are either significant or tolerable.