(422h) A Microchannel Water-Gas Shift Reactor Simulation and Optimization for a Mobile Application

A three-dimensional model is developed to simulate the behavior of a single-channel water-gas shift microreactor. The flow regime is assumed to be steady and laminar in a microreactor with isothermal walls. A water-gas shift reaction kinetic is applied to simulate the surface reaction over a 0.5 wt% Pt/TiO₂ catalyst with 41 m²/g specific surface area. The composition of the feed gas is taken as a typical outlet of an autothermal reformer (ATR). An assembly of such microreactors is intended for use as a component in a micro-fuel processor device for a low-power PEM fuel cell in a mobile application. Numerous parametric studies are conducted to investigate the effects of the feed gas temperature and moisture content, channel geometry (cross-sectional aspect ratio) and length, and gas space velocity on the performance of the microreactor. A statistical model is implemented to obtain optimum design and operating conditions of the reactor. It is revealed that, within our existing constraints, the optimal reactor consists of a square cross-section channel (100 µm hydraulic diameter) and 22 mm length, with feed gas temperature of 270°C and steam content of 24% at a space velocity of 1000 h^-1.