Heat Transfer Enhancement of Steam Reformation by Passive Flow Disturbance Inside the Catalyst Bed

Because of the potential for high efficiency and low emissions, hydrogen powered systems are considered to be the next generation power source for both stationary and transportation applications. Providing a hydrogen source is a critical challenge. Steam reforming processes are demonstrated for producing hydrogen for fuel cell and other applications. Generating hydrogen via steam reformation requires that heat energy be transferred to the reactants to support the endothermic reaction. For a cylindrical steam-reforming reactor, large thermal gradients between the heat source (reactor wall) and reactor centerline create a nonideal condition for complete conversion. This gradient is caused by insufficient heat transfer inside the catalyst bed. Passive flow disturbance inside the catalyst bed is a potential method to enhance the heat and mass transfer in the steam-reforming process. This paper presents experimental research that investigates the effect of changing the flow pathway inside the reactor to improve the heat and mass transfer and thus enhance fuel conversion. Based on the experimental results, a 14% increase of methanol fuel conversion was achieved via the passive flow disturbance enhancement. The tradeoff was an extra pressure drop of 2.5 kPa across the reactor. A 30 h experimental run does not show a significant change in degradation rate for the passive flow disturbance. The results of this study contribute to the improvement of reformer design for better fuel processing system performance.