Study of different designs of methanol steam reformers: Experiment and modeling

Abstract

Three reformers with different designs (multi-channel, radial and tubular) were developed for thermal integration with a high temperature polymeric electrolyte membrane fuel cell (HT-PEMFC). They were characterized experimentally at temperatures between 443 K and 473 K, using the commercial catalyst G66 MR from Sud-Chemie (CuO/ZnO/Al2O3). The reactors were modeled and simulated using a computational fluid dynamics (CFD) analysis. The models were validated using experimental data. The results showed that the multi-channel design is the best solution for thermal integration with a HT-PEMFC, presenting high methanol conversion and low pressure drop. Regarding the heat transfer ability, the multi-channel showed also the best performance, presenting the lowest temperature sink among the studied reformers. The low flow velocities and the absence of metallic surfaces in the radial reformer had detrimental effect on the heat transfer. Concerning the flow distribution a coefficient of variation of 0.6% was observed in the multichannel reformer. A quasi plug flow behavior was found in the tubular and a multichannel (channels region only) reformer, while in the radial a not fully developed laminar flow was found. At temperatures lower than 473 K was found that the reformate stream did not require further purification to be fed to a HT-PEMFC due to the low CO concentration (<1600 ppm). The advantages and limitations of each design is discussed based on experimental data and CFD modeling. Copyright