The laminar flame speeds of C 3 oxygenated fuels ( n -propanol, propanal and acetone) and hydrocarbon (propane) were measured in a combustion bomb to compare combustion characteristics of C 3 alcohol, aldehyde, ketone, and alkane Propanal shows the highest flame speeds while acetone gives the lowest one The experimental observations are further interpreted with chemical kinetic models The effects of distinctive molecular structures on the fuel consumption pathways are clarified Propanal generates a large H atom pool that enhances the oxidation, leading to the highest flame speeds However, acetone forms methyl radical (CH 3 ) and has lower flame speeds as a consequence The calculated maximum concentrations of H, OH, and CH 3 confirm this analysis It is found that propanal yields the highest H and OH concentrations while acetone produces the lowest H and OH concentrations among all tested fuels Moreover, acetone presents higher CH 3 concentration, especially for fuel rich condition n -Propanol and propane show comparable flame speeds and similar radical concentrations, especially H and OH The different kinetics among hydrocarbon species with the same carbon numbers can provide a horizontal view in the hierarchical hydrocarbon chemistry

A comparative study of n-propanol, propanal, acetone, and propane combustion in laminar flames

Cold start emissions of an ethanol-fuelled engine with heated intake air and fuel

This work describes the improvements on exhaust emissions and cold start obtained through utilization of a new type of cold-start auxiliary system for ethanol-fueled engines. Lower amounts of the gasoline used to help cold start and of ethanol injected during cold start and warm-up were used via introduction of a fuel injector in the new cold-start auxiliary system. The redesigned system allowed for faster and uniform cold start, in comparison to the conventional system, of around 31.1%. Reductions of raw hydrocarbon and carbon monoxide emissions in the cold stage of the FTP-75-based emissions test cycle were about 8.6 and 17.2%, respectively, while oxides of nitrogen and aldehyde emissions remained unchanged.

Reducing exhaust emissions in ethanol-fueled engines during cold start

This work presents results and analysis of experiments on aldehyde and the regulated pollutants CO, HC, and NOA emissions, with varying engine-running parameters. An ethanol-fueled vehicle was tested in a chassis dynamometer, following a standard urban cycle test procedure. The test simulated a medium-distance trip in an urban area, of approximately 5.8 km, with a warmed-up engine. The running parameters tested in the experiments were mixture equivalence ratio, the additional air flow used in decelerations (dash pot), the fuel interruption function in decelerations (cutoff), and gear-change speed. The results pointed to a reduction on aldehyde emissions for lower gear-change speeds and for richer fuel mixtures.

Influence of engine operating parameters on aldehyde emissions from an ethanol-fueled vehicle

Aqueous fueled engines have the potential for lower emissions and higher engine efficiency than engines fueled with gasoline or diesel fuels. Past attempts to burn aqueous fuels in over-the-road vehicles have been unsuccessful due to difficulties in initiating combustion under varying environmental conditions. Ethanol-water mixtures, called Aquanol, require no special emulsifications to create and should provide significant emission reductions in CO and NOx, while producing no net CO2 emissions. Aldehydes, a part of the hydrocarbon emissions, are expected to increase with alcohol-based fuels. Understanding what parameters affect aldehyde formation will help create reduction strategies. Detailed detection of exhaust emissions is necessary for a quantitative comparison. Redundant measurements with two special purpose detectors will be used for emission comparisons. A van supplied by Valley Transit of Lewiston, Idaho has been converted to catalytic ignition. In order to make the vehicle operate on either gasoline or Aquanol, modifications to the fuel handling, engine management, and ignition system were necessary. A three-part vehicle test plan is currently underway to compare performance, fuel economy, and emissions between Aquanol and gasoline fuels.

Catalytic ignition of aquanol

Aldehyde formation and emissions from alcohol fueled engines are presented in this paper Several chemical kinetic models on the mechanism leading to aldehyde formation have been examined to explore the appropriate control methods to reduce exhaust aldehyde emissions Control of aldehydes in exhaust emissions by suitable alteration of engine operating parameters, by in cylinder treatment with additives like aniline and water, by external treatment like airpreheating, secondary air injection cooling water rate and exhaust treatment are examined The concept of surface ignition for alcohol fuels is briefly presented as a long range objective for using alcohols with minimal aldehyde emissions

B. S. Murthy

Papers

Formation and control of aldehydes in alcohol fueled engines