Search Results

An intermittent sampling valve was used to investigate local fuel H/C ratio and species concentrations in an operating DI diesel engine. Additionally, predictions of carbon and hydrogen originating from particulates and nonmethane hydrocarbons (carbon and hydrogen remainders) were made by calculation. Sample H/C ratio was used to assess local fuel phase as gaseous or liquid. Evidence of intermediate species quenching in the lean region between spray plumes was found under low swirl. Reduction in the rate of penetration under high swirl may account for the observed loss in efficiency under this condition.

This paper describes a method and apparatus intended to minimize hydrocarbons (HC), carbon monoxide (CO), and nitric oxide (NO) in spark ignition engine exhaust by utilizing the unused displacement of the engine at part loads as an internal thermal reactor. The method used is to induct exhaust gas plus air into one portion of the cylinder and unthrottled fuel-air charge into the balance. The fuel-air charge is rich to minimize NO formation, but, as a result, the products of combustion contain HC and CO. Air is added to these products before re-induction to provide additional oxygen to complete the oxidation which is promoted by the high pressures and temperatures of compression and combustion. Load control is achieved by varying the relative amounts of fuel-air charge and recirculated exhaust. Experimentally, it was shown that the necessary stratification existed until the spark occurred but not thereafter.

This paper indicates why certain exhaust constituents from automotive vehicles are considered pollutants, describes the formation of these pollutants in automotive operation, and details techniques being used and considered to control these pollutants. The formation of pollutants-carbon monoxide, nitric oxide, hydrocarbons, particulates, and odor-in a variety of engine types and under a variety of conditions is described in detail. Vehicle emissions are also analyzed for real motor vehicle operation.

Ethylene, propylene, n-butane, and 1-butene, which make up a large portion of the photochemically reactive hydrocarbons in automobile exhaust, were reacted individually and as a mixture in a turbulent flow, heated reaction tube made of mild steel. Methods of predicting the total hydrocarbon disappearance by use of a general empirical equation are presented. Techniques for using hydrocarbon composition and carbon monoxide data to predict exhaust photochemical reactivity and CO concentration from total hydrocarbon disappearance correlations are suggested. Results show that total hydrocarbon reaction was generally strongly dependent on temperature and on oxygen concentration between 1% and 5%, and was less dependent on initial hydrocarbon concentration. Gas Chromatograph data showed that during certain individual hydrocarbon reactions, the formation of other photochemically reactive hydrocarbons could increase smog-forming potential despite a decreasing total hydrocarbon concentration.

This paper describes a method for studying reactions of hydrocarbons in S.I. engine exhaust gases. The reaction of ethane is described using an Arrhenius model (experimentally E = 86,500 cal/mole) for the rate of ethane diappearance and empirical correlations for distributions of the products carbon monoxide, ethylene, formaldehyde, methane, acetylene, and propane as a function of the fraction of ethane reacted. The results show that the nature of partial oxidation products from a nonreactive hydrocarbon may be less desirable from an air pollution viewpoint than the initial hydrocarbon.

To determine the effects of knock in a spark-ignition, single-cylinder engine with cooled exhaust upon the exhaust composition, exhaust products (CO, CO2, and total hydrocarbons) were measured by non-dispersive infrared analyzers (NDIRA) and by a flame ionization detector (FID). Individual hydrocarbons were separated on a gas-liquid chromatograph. In fuel-rich mixtures, the FID indicated noticible decreases in the hydrocarbon concentrations in the presence of knock. The NDIRA did not indicate a decrease in the hydrocarbons at knock of lower intensities but showed decreases in hydrocarbons at knock of higher intensities. Chromatograms indicated a preferential decreases in acetylene at the time of knock, causing different responses at lower intensities. In fuel-lean mixtures, no apparent effect of knock on the hydrocarbons was indicated.

This paper reviews the source of the different emissions from an automobile. The exhaust is the major source of air pollution. This is composed of completely oxidized constituents such as H2O and CO2, both of which are considered harmless. Emphasis is placed on the partially oxidized components -- nitrogen oxide, carbon monoxide, and hydrocarbons -- as being the major pollutants. NO and CO are formed primarily in the bulk gases, whereas hydrocarbons are formed in the quench area. Discussed are several possible methods that could be considered in attempting to eliminate these pollutants. The authors are confident an answer will be found to this emission problem and that internal combustion engines will be used to power private vehicles rather than electricity.

The purpose of the tests conducted on a single-cylinder laboratory engine was to determine the mechanism of combustion that affect exhaust emissions and the relationship of those mechanisms to engine design and operating variables. For the engine used in this study, the exhaust emissions were found to have the following dependence on various engine variables. Hydrocarbon emission was reduced by lean operation, increased manifold pressure, retarded spark, increased exhaust temperature, increased coolant temperature, increased exhaust back pressure, and decreased compression ratio. Carbon monoxide emission was affected by air-fuel ratio and premixing the charge. Oxides of nitrogen (NO + NO2 is called NOx) emission is primarily a function of the O2 available and the peak temperature attained during the cycle. Decreased manifold pressure and retarded spark decrease NOx emission. Hydrocarbons were found to react to some extent in the exhaust port and exhaust system.