Numerical Investigation of the Transport Phenomena in Microchannel Steam Reforming Reactors for Hydrogen Production

Abstract

The fundamental transport phenomena in microchannel steam reforming reactors for hydrogen production are studied using dimensionless numbers. Numerical simulations are performed using chemical kinetics coupled with fluid mechanics to study different phenomena that lead to transport. The dimensionless numbers in transport phenomena are principally analyzed to provide insight into the reaction behaviors and characteristics. The effects of reaction pressure, catalyst porosity, and inlet Reynolds number are evaluated to understand the physical and chemical processes involved in the systems. The results indicate that hydrogen productivity is favored kinetically at higher pressures, but high process efficiency is difficult to achieve. Momentum diffusivity dominates the diffusion behavior, and heat diffuses slowly. Catalyst porosity is vital to ensuring effective operation. Higher levels of porosity allow more efficient hydrogen production and may resolve the problem of mass-transfer limitation. Convective rates dominate mass transfer, and diffusion contributes insignificantly. The tortuous Reynolds number depends heavily on the level of porosity. The Nusselt and Sherwood numbers depend heavily on the pressure but do not vary significantly with the Reynolds number.