Numerical Study on NO Conversion Characteristics of Ceramic and Metallic Monoliths Under Steady-State External Heat Loss in Marine After-Treatment System

This study aims to numerically analyze the ceramic and metallic monoliths as a catalyst substrate of selective catalytic reduction (SCR) system in marine applications. The representative elementary volume of each catalyst substrate was chosen and pressure drop through the volume was numerically calculated to estimate the parameters for the porous model. The fixed-bed experiment using a powder catalyst of 3V7MO/TiO₂ was conducted in the way to estimate the global one-step reaction kinetics. Thus, the NO conversion from both ceramic and metallic monolith catalysts was calculated by a porous model with a simplified reaction mechanism to numerically investigate the flow and thermal characteristics within the two types of catalyst substrate. As an extreme condition, an external heat loss with an ambient temperature of 300 K was set to the reactor wall. Predicted results indicate that the NO conversion performance of ceramic monolith is better in general due to the lower heat loss from the cold wall. However, it is found that there is a trade-off relationship between the residence time and the external heat loss. Heat management such as thermal insulation plays an essential role to maximize the benefits of using metallic monolith as a catalyst substrate for practical marine applications.