Heat energy transport characteristics of microchannel reactors for hydrogen production by steam-methanol reforming on copper-based catalysts

Abstract

Numerical simulations are carried out to understand the heat energy transport characteristics of microchannel reactors for hydrogen production by steam-methanol reforming on copper-based catalysts. Enthalpy analysis is performed and the evolution of energy in the oxidation and reforming processes is discussed in terms of reaction heat flux. The effects of solid thermal conductivity, gas velocity, and flow arrangement on the thermal behavior of the reactor is evaluated in order to fully describe the thermal energy change in the reactor. The results indicate that the thermal behavior of the reactor depends upon the thermal properties of the walls. The change in enthalpy is of particular importance in exothermic and endothermic reactions. The net enthalpy change for oxidation and reforming is negative and positive, but the net sensible enthalpy change is always positive in the reactor. The wall heat conduction effect accompanying temperature changes is important to the autothermal design and self-sustaining operation of the reactor. The solid thermal conductivity is of great importance in determining the operation and efficiency of the reactor. The reaction proceeds rapidly and efficiently only at high solid thermal conductivity. The reaction heat flux for oxidation and reforming is positive and negative. The change in flow arrangement significantly affects the reaction heat flux in the reactor. The parallel flow design is advantageous for purposes of enhancing heat transfer and avoiding localized hot spots.