A Porous Media Burner for Reforming Methanol for Fuel Cell Powered Electric Vehicles

This work examines the characteristics of a methanol fueled porous media burner, the principles of which may be used as a basis for a practical radiant heat source for an on-board catalytic methanol reformer. The burner uses a conventional engine port fuel injector designed for methanol use.

The spray from the injector was impinged upon the bottom of a stack of two or three pieces of ceramic foam. The ceramics were 2.5 cm thick, 10 cm in diameter and were enclosed in a quartz cylinder for visualization. The upstream ceramic acted as a flame holder and the surface of the downstream ceramic was the radiation source. The range of air and fuel flow rates over which stable combustion was possible was investigated. Fuel flow rates between 0.12 and 0.48 gm/s were examined. Overall equivalence ratios between 0.65 and 0.2 resulted in stable combustion. Complete combustion of the methanol was not achieved within the ceramics under most conditions, in which case a non-premixed (diffusion) flame was emitted from the downstream ceramic.

Temperature profiles measured along the exit planes of the 2nd and 3rd ceramics showed the combustion was taking place along the central axis of the burner within a 5 cm diameter region. This was due to the relatively narrow spray angle of the injector nozzle. The temperature profiles were relatively flat within the central area, with surface temperatures approximately 750°C for the lowest fuel flow rate and 1050°C for the highest fuel flow rate. Based upon black body behavior these correspond to radiant emissions between 62 and 174 kW/m² for the 5 cm diameter high temperature core region.