Formation and control of aldehydes in alcohol fueled engines

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

Abstract: 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

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

Abstract: This works presents the exhaust emission levels from a flexible fuel engine with heated intake air and fuel during cold start operation. A vehicle powered by an ethanol-fuelled flexible fuel engine was used in the experiments, following the US FTP-75 test schedule. The conventional gasoline injection system for cold start assistance was removed. Heating of intake air and fuel was provided by electric resistances. The results demonstrate that intake air and fuel heating can attend cold start expectations and simultaneously reduce exhaust hydrocarbon and carbon monoxide emissions.

Reducing exhaust emissions in ethanol-fueled engines during cold start

Abstract: 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.

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

Abstract: 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.

Catalytic ignition of aquanol

Abstract: 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.

Emissions from Combustion Engines and Their Control

Abstract: This standard text for the automotive industry explains in detail the fundamentals of emission formation and control for gasoline and diesel engines. These concepts can be applied to other combustion systems, such as gas turbines and stationary power plants. Topics of discussion include: combustion in homogeneous mixtures; effect of design and operating variables on gasoline engine exhaust emissions; hydrocarbon evaporation emissions; diesel engine combustion emissions and controls; emission instrumentation; and automotive exhaust emission testing. 200 references, 197 figures.

A Single-Cylinder Engine Study of Methanol Fuel-Emphasis on Organic Emissions

Abstract: Exhaust emission and performance characteristics of a single-cylinder engine fueled with methanol are compared to those obtained either with gasoline or a methanol-water blend. Our measurements of engine efficiency and power, and CO and NO/sub x/ emissions agree with trends established in the literature. Consequently, the emphasis is placed on organic emissions (unburned fuel including hydrocarbons, and aldehydes), an area in which there is no consensus in the literature. In all cases with methanol fueling, the unburned fuel (UBF) emissions were virtually all methanol as opposed to hydrocarbon compounds. Without special measures to overcome methanol's large heat of vaporization, UBF emissions were four times greater with methanol than those with gasoline. Similarly, aldehyde emissions were an order of magnitude greater with methanol. These high levels of organic emissions with methanol were related to inadequate fuel-air mixture preparation, which was caused by methanol's large heat of vaporization. Modifying the single-cylinder engine intake system to improve vaporization reduced UBF emissions 80 to 90% with methanol and 30 to 50% with gasoline. Aldehyde emissions were also significantly reduced by improving mixture preparation, but remained three to four times greater for methanol than for gasoline. Blending 10% water with methanol resulted in: (1) reducedmore » engine efficiency and power, (2) increased UBF emissions, (3) no measurable effect on aldehyde and CO emissions, and (4) reduced NO/sub x/ emissions. Our tests indicate that the advantages of blending water with methanol are outweighed by the disadvantages.« less

Effect of compression ratio on exhaust emissions and performance of a methanol-fueled single-cylinder engine

Abstract: One of the reasons methanol is considered an attractive alternative fuel for automobiles is its high octane quality, which may allow the use of high compression ratio (CR) engines. To evaluate compromises between engine efficiency and exhaust emissions, a methanol-fueled single-cylinder engine was run at CR's from 8 to 18. At each CR, engine speed and airflow were constant at 1200 rpm and about half throttle, respectively; equivalence ratio (phi) was varied from 0.7 to 1.1; and spark timing was varied from best power (MBT) to 10/sup 0/ retarded. Knock was observed only at CR = 18 with MBT spark timing. Increasing CR from 8 to 18 while maintaining MBT spark timing increased efficiency about 16%, but also increased NO/sub x/ and unburned fuel (UBF) emissions. Some previous studies have reported decreased NO/sub x/ emissions with increased CR, possibly because MBT spark timing was not maintained. Results of this study indicate that constant NO/sub x/ emissions can be maintained by retarding spark timing while increasing CR to improve efficiency. Retarding spark timing, however, only marginally reduced UBF emissions. Vehicle tests are necessary to define the optimum CR for methanol fueling because exhaust emission trends and knocking tendency may be differentmore » than those observed with this single-cylinder engine.« less