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.

High-Purity Hydrogen Production by CO2 Addition for Sorption-Enhanced Steam Methane Reforming at a Temperature Below 600 °C

“…The proton exchange membrane fuel cell (PEMFC) is a promising energy technology that uses hydrogen to generate electricity, offering the advantages of zero pollution and high efficiency. PEMFCs have potential applications in various fields such as portable power, transportation, and stationary power generation. − The main methods for H 2 production from fuel reforming include steam reforming (SR), partial oxidation, autothermal reforming, and decomposition, − among which steam methane reforming (SMR) is a mature and commercialized technology. The traditional SMR reactor is operated at high temperature and pressure, typically 800–900 °C and 20–30 atm .…”