Experimental investigation of gaseous reactive flows around catalytically coated micro-wires

The advantages of catalytic heterogeneous combustion for compact, autonomous power generation have been highlighted by recent developments in the field of meso-scale burners. With this perspective, the reactive flow around catalytically coated cylinders, in the regime of Reynolds and Peclet numbers that are relevant to such small-scale devices, was investigated experimentally. Preliminary experimental results of premixed methane-air flows over a catalytically coated wire are presented. The configuration under investigation consists of a metallic cylinder of 0.6mm diameter coated with Pt on an alumina washcoat. Methane combustion was established on the surface of the catalyst by placing it in the outlet flow of a pre-heater that controlled temperature, composition and velocity of the methane-air pre-mixture. The flow was maintained at Reynolds numbers in the 11-24 range which have been shown to be appropriate values for gaseous flows in small-scale power generation. The temperature of the catalytic wire was measured with a thermocouple welded to the support metal of the wire. Gas chromatography/ mass spectroscopy of major combustion species was performed downstream of the catalytic wire. Both temperature and concentration of methane and CO follow a non-monotonic trend. PIV measurements of the flow were conducted and the resulting velocity fields show that both the Reynolds number and the equivalence ratio of the flow influence the structure of the flow field. Such behavior indicates the importance of diffusive/convective transport in addition to catalytic chemistry in this reactive flow.