Thermal and Fluid Flow Effects of Ceramic Honeycomb on the Stabilization of Methanol Partial Oxidation Reaction

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In this paper, non-catalytic partial oxidation reaction (fuel-rich combustion) of methanol was investigated experimentally when the reaction was stabilized in the vicinity of the ceramic honeycomb as a porous material inserted in the reactor. The experiment was conducted under various conditions of the gaseous mixture flow rates and velocity profiles. Temperature distributions of combusting gas and honeycomb surface were measured and the flame shapes were observed to evaluate the reforming characteristics and the reaction stability. Better stability and higher conversion rate were achieved in a wide turn down ratio range when the conical flame was formed. However, in the considerably smaller flow rate conditions, the flame attached to the honeycomb and the methanol conversion was deteriorated due to the heat loss effect of the honeycomb. In too much high flow rate conditions, on the other hand, the flame was stretched asymmetrically and the reaction became unstable. By introducing the mixture gas as a central jet in the reforming chamber, the stability of the flame was improved without deteriorating the reforming efficiency since the smaller velocity gradient in the near-wall surrounding region enhanced the flame stability.