Computational insights into steady-state and dynamic Joule-heated reactors†

Abstract

Joule-heated reactors could drive high-temperature endothermic reactions without heat transfer limitations to the catalyst and with high energy efficiency and fast dynamics under suitable conditions. We use 3D computational fluid dynamics (CFD) to investigate the power distribution, temperature field, and flow patterns in continuous steady-state and rapid-pulse Joule heated reactors with carbon fiber paper as the heating element. The model is in good agreement with published experimental data. We demonstrate flow recirculation under typical conditions and derive criteria for their suppression. We showcase rapid (seconds or shorter) and uniform heating to very high temperatures (>1500 °C) with minimal heating of the flowing gas, which could reduce undesired gas-phase chemistry. A simple energy model indicates that a high applied voltage and heating elements of high electrical conductivity and low volumetric heat capacity accelerate heating. We report heat transfer enhancement during rapid pulsing, a form of process intensification enabled by dynamic operation.