New correlations for the overall heat transfer coefficient Uth, designed for use in one-dimensional reactor models for wall-cooled tubular fixed-bed reactors, are presented. These correlations are applicable for estimating both critical conditions related to thermal runaway and reactor performance under safe operating conditions. They were derived by comparing a 1D and a 2D model, initially for Fischer-Tropsch synthesis (FTS) as a case study, and subsequently extended beyond this specific reaction system. Additionally, a novel approach is introduced for estimating critical runaway conditions without relying on a reactor model. This method is based solely on reaction kinetics, the effective thermal conductivity λrad, and the heat transfer coefficient αwall, which accounts for heat transfer near the reactor wall.
Kern et al. (Wed,) studied this question.