UNS: Shock Tube Measurements of Aldehyde and Ketone Rate Constants Using Enhanced Laser Absorption

Stanford University, Stanford CA

Investigators

Abstract

1508748 (Hanson) This project will investigate how basic elements of many commonly used fuels react under conditions typical in an engine. Laser-based optical methods will be used to track the behavior of these elements during reaction. The potential outcome of the proposed study will help to reduce emissions from engine combustion. The PI proposes to use a shock tube study to address aldehyde and ketone reactions, a topic having high level of relevance to the combustion of emerging biofuels. The emissions of aldehydes and ketones have important environmental and health consequences. Both types of species are formed in significant quantities as intermediates during the early stages of hydrocarbon oxidation, and significant emissions of these species can occur from engines if combustion is incomplete (e.g. quenched) before full ignition. Advanced, laser based diagnostics will be used for the experimental investigation, including laser absorption diagnostics for formaldehyde, acetaldehyde, and hydroxyl radical (OH), and laser absorption determinations for CO by using cavity enhanced absorption with emission from a quantum cascade laser, providing sub-ppm sensitivity. These measurements will take advantage of our recent development of an enhanced, ultra-high-sensitivity CO laser absorption diagnostic that can provide sub-ppm sensitivity in shock tube experiments.