Measuring Ignition Temperature and Heat Generation From Ethanol-Oxygen-Water Mixtures on Platinum

The surface temperature and heat generation from reactions of ethanol-water-oxygen-nitrogen mixtures on a platinum wire catalyst were determined using microcalorimetry. A 127-micron diameter, 99.95% Pt coiled wire was placed crosswise in the quartz tube of a plug flow reactor. A sourcemeter with a four-lead technique allowed the platinum wire to measure its average temperature by serving as a resistance thermometer, and enabled us to determine the amount of heat generated from surface reactions. Ignition temperatures varied from 380 to 570 K and heat generation from 0.8 to 11.8 W/cm² depending on the absolute amounts of ethanol and oxygen, the ethanol:water ratio, and the fuel-oxygen equivalence ratio. The addition of water to ethanol showed little to no effect on either the ignition temperature or the heat generation on the platinum wire at the maximum 60:40 ethanol:water mole ratio (∼83:17 ethanol:water liquid volume ratio) reported here. These experimental results aid in understanding the heat transfer processes of catalytic igniters used to ignite fuel-lean mixtures.