Numerical Simulation Of Methanol Steam Reforming In Micro-channel Reactor

Aiming at the issue of hydrogen supply for Proton Exchange Membrane Fuel Cell (PEMFC), this dissertation brought forward the solution of on-spot Steam Reforming of Methannol (SRM). To make it true, a flat cascading micro-channel catalytic reactor was designed, in which the flow, mass and heat transfer, and reaction processes were numerically simulated. Firstly, this paper introduced the structure of the reactor, method for catalyst preparation and experimental devices system. Double-liquid-channel structure, which means the heat channel and the reaction channel, is used in the reactor. The former channel supplies the necessary heat energy for the catalytic steam reforming reactions which take place in the latter one, and they are separated to avoid the heat air and the reactant getting mixed. The catalyst gained from the technology of Cold Gas Drived Ejection (CGDE) is a layer of compact membrane ,and the reforming reactions just happen on the surface of that. Based on this, a 2D state model of one single reaction unit is eatablished. Resolution of the model is performed by the commercial CFD software FLUENT 6.1.22, in which there is a special module for wall surface reaction simulation. The kinetic model is cited from other's research because the experiment has not began yet. This paper simulates the effect of various channel sizes, inlet temperatures, inlet velocities, and inlet molar ratio of steam to methanol on the reaction, exhaust composition and outlet temperature, through which the best parameters are gained. They are: height and length of the reaction channel, 0.5 and 10 mm respectively; molar ratio of steam to methanol and inlet temperature of reactant, 1.3 and 523K respectively; inlet temperature and velocity of hot air in heat channel, 650 K and 3 m/s respectively. These parameters are then combined in a same case and the computation results shows that methanol is 100% conversed, CO volumetric fraction is 1.7%and 0.68 for H2 with the approximate selectivity to CO2 92.7%. The improvement in heat transfer caused by the use of micro-channel technology is calculated. The total heat transfer coefficient between the two channels makes 766.6 W /( m 2? K), while in common gas to gas case it is only 10~30 W /( m 2? K). At last the simulation results are validated by comparasion with the similar experimental outcomes of other's research.