Thomas M. Baines

CHARACTERIZATION OF PARTICULATE AND GASEOUS EMISSIONS FROM TWO DIESEL AUTOMOBILES AS FUNCTIONS OF FUEL AND DRIVING CYCLE

Particulate and gaseous emissions from two-light-duty diesel vehicles were measured over eight operating schedules, using five different fuels. Characterization included regulated exhaust emissions and a number of unregulated constituents. Non-routine gas measurements included phenols, hydrocarbon boiling range, and aldehydes. Particulate characterization included mass rates and concentrations, visible smoke, aerodynamic sizing, total organics, sulfate, phenols, trace elements, and major elements. Statistical analysis of emissions data was undertaken using fuel properties and operating schedule statistics as independent variables. Regressions were computed for a few variables, and analysis of variance and multiple comparisons were used where the data were not suitable for regression analysis.

Simulation of High Altitude Effects on Heavy-Duty Diesel Emissions

Exhaust emissions from heavy-duty diesel engines operating at high altitude are of concern. EPA and Colorado Department of Health sponsored the project to characterize regulated and selected unregulated emissions from a naturally-aspirated Caterpillar 3208 and a turbocharged Cummins NTC-350 diesel engine at both low and simulated high altitude conditions (about 6000 ft). Emissions testing was performed over cold- and hot-start transient cycles as well as selected steady-state modes. Additionally, the turbocharged engine was operated with mechanically variable and fixed retarded fuel injection timing to represent normal and malfunction conditions, respectively. High altitude operation generally reduced NOx emissions approximately 10% for both engines. Average composite transient emissions of HC, CO, particulate matter, and aldehydes measured at high altitude for the naturally-aspirated engine were 2 to 4 times the levels noted for low altitude conditions. The same emission constituents from the turbocharged engine at high altitude with normal timing were 1.2 to 2 times the low altitude levels, but were 2 to 4 times the low altitude levels with malfunction timing.

EFFECTS OF FUEL VARIABLES ON DIESEL EMISSIONS

The body of information presented in this paper is directed towards engineers in the field of environmental sciences involved in measuring and/or evaluating the emissions from a variety of diesel engines or vehicles. This paper summarizes recent data obtained by EPA on identification and quantification of different emissions (i.e. characterization) from a variety of diesel engines. Extensive work has been done comparing emissions from some light duty diesel and gasoline passenger cars. The work on the diesel vehicles was expanded to include tests with five different diesel fuels to determine how fuel composition affects emissions. This work showed that use of a poorer quality fuel frequently made emissions worse. The investigation of fuel composition continued with a project in which specific fuel parameters were systematically varied to determine their effect on emissions. EPA is presently testing a variety of fuels derived from coal and oil shale to determine their effects on emissions. EPA has also tested a heavy duty Volvo diesel bus engine designed to run on methanol and diesel fuel, each injected through its own injection system. The use of the dual fuel resulted in a reduction in particulates and NO but an increase in HC and CO compared to a baseline Volvo diesel engine running on pure diesel fuel. Finally, some Ames bioassay tests have been performed on samples from the diesel passenger cars operated on various fuels and blends. An increase in Ames test response (mutagenicity) was seen when the higher aromatic blend was used and also when a commercial cetane improver was used. Samples from the Volvo diesel bus engine fueled with methanol and diesel fuel showed that use of a catalyst increased the Ames response.

A Study of the Potential Impact of Some Unregulated Motor Vehicle Emissions

Studies of emissions from vehicles equipped with catalysts have shown that some unregulated emissions can increase when a catalyst is used. One example of this is sulfuric acid, which has been studied extensively. Other unregulated emissions include ammonia and hydrogen cyanide. In a number of studies, these unregulated pollutant emissions have been measured from light-duty vehicles and heavy-duty engines. These emission levels were used in air quality dispersion models to predict the resultant air quality levels. The ambient concentrations predicted for each pollutant were then compared to suggested concentrations at which adverse health effects may be found to determine if additional monitoring or control would be indicated for these pollutants. It was determined that mobile source emissions of sulfuric acid, hydrogen cyanide, and ammonia do not in general result in ambient levels of concern for the air quality situations studied.

Emissions from two methanol-powered buses

Emissions from the two methanol-powered buses used in the California Methanol Bus Demonstration have been characterized. The M.A.N. SU 240 bus is powered by M.A.N.s D2566 FMUH methanol engine, and utilizes catalytic exhaust aftertreatment. The GMC RTS II 04 bus is powered by a first-generation DDAD 6V-92TA methanol engine without exhaust aftertreatment. Emissions of HC, CO, NO/subX/, unburned methanol, aldehydes, total particulates, and the soluble fraction of particulate were determined for both buses over steady-state and transient chassis dynamometer test cycles. Emission levels from the M.A.N. bus were considerably lower than those from the GMC bus, with the exception of NO/subX/. Comparison of emission levels from methanol-and diesel-powered buses indicates that substantial reductions in emissions are possible with careful implementation of methanol fueling.

Sulfuric Acid Emissions from Light Duty Vehicles

Systems used by the Office of Mobile Source Air Pollution Control of EPA to measure and analyze automotive sulfuric acid emissions are discussed. This system involved mixing the entire vehicle exhaust with dilution air in a dilution tunnel. Sulfuric acid samples are collected by passing a small portion of the dilute exhaust through Fluoropore filters. The sulfuric acid content of the filters is determined by an automated barium chloranilate method. Test results from a number of advanced prototype vehicles including two stratified charge cars, a Dresser carburetor vehicle, three dual catalyst cars, and a 3-way catalyst car are described.

Heavy Duty Diesel Particulate Emission Factors

For the past several years, EPA has been measuring particulate emissions from a variety of heavy-duty diesel engines through contracts with Southwest Research Institute. Particulate emissions samples have been collected using an exhaust splitter to divert a fraction of the engine exhaust into a standard dilution tunnel. A small fraction of the diluted exhaust from the tunnel is pulled through a filter from which particulate mass and, in some cases, organic content of the particulate is determined. This paper discusses the sampling system and gives particulate emission factors that have been computed from truck and bus fuel consumption data as well as average truck and bus speed data from New York and Los Angeles (freeway and nonfreeway usage). Average particulate emission test results (steady state tests) for 2-stroke engines were 4.74 g/kg fuel and for 4-stroke engines were 2.64 g/kg fuel. Using average particulate emissions results, a particulate emission factor range of 0.8 to 1.3 g/km was computed. Na...

EPA MOTOR VEHICLE EMISSIONS CHARACTERIZATION PROJECTS ON LIGHT AND HEAVY DUTY DIESELS

The body of information presented in this paper is directed towards engineers in the field of environmental sciences involved in measuring and evaluating the emissions from a variety of diesel engines or vehicles. This paper summarizes recent data obtained by EPA on identification and quantification of different emissions (i.e. characterization) from a variety of diesel engines. The effects of turbocharging, advanced injection timing, indirect vs. direct injection, exhaust gas recirculation (EGR), and different fuel pumps on HC, CO, NO/sub x/, sulfates, aldehyde, and particulate emissions were determined by testing several heavy duty diesel engines. A heavy duty gasoline engine was tested for comparison. Limited testing was done on a diesel bus engine under malfunction conditions (conditions different from manufacturers recommended specifications).

HEAVY-DUTY DIESEL EMISSIONS AS A FUNCTION OF ALTERNATE FUELS

Exhaust emissions from a Mack EM6-300 heavy-duty diesel engine were characterized with five different fuels during transient and steady-state operation. A control fuel (Phillips D-2) was used for baseline emissions, and as a base stock in three alternate fuel blends containing EDS or SRC-II middle distillates or used lubricating oil. The fifth fuel tested was neat soybean oil, heated to 145 degrees. Emission measurements included HC, CO, CO2, NOx, visible smoke, particulate, IHC, aldehydes, odor (DOAS), phenols, sulfate, elemental composition, particle sizing, SOF, SOF boiling point distribution, BaP, Ames bioassay and HPLC fractionation. HC, CO, NOx and particulate emissions were similar for this engine on all fuels tested with exception of higher particulates for the soybean oil and higher NOx for the SRC-II blend. Ames response was highest for the EDS and SRC-II blends. The BaP level was highest for the soybean oil.

COMPARISON OF PETROLEUM AND ALTERNATE-SOURCE DIESEL FUEL EFFECTS ON LIGHT-DUTY DIESEL EMISSIONS

Exhaust emission data from several fuel effects studies were normalized and subjected to statistical analyses. The goal of this work was to determine whether emission effects of property variation in alternate-source fuels were similar, less pronounced, or more pronounced than the effects of property variation in petroleum fuels. A literature search was conducted, reviewing hundreds of studies and finally selecting nine which dealt with fuel property effects on emissions. From these studies, 15 test cases were reported. Due to the wide variety of vehicles, fuels, test cycles, and measurement techniques used in the studies, a method to relate them all in terms of general trends was developed. Statistics and methods used included bivariate correlation coefficients, regression analysis, scattergrams and goodness-of-fit determinations. Insertion of alternate-source fuel properties into exhaust emissions prediction equations based on petroleum fuel results indicated that the effects of alternate-source fuel property changes on exhaust emissions were statistically indistinguishable from those associated with petroleum fuels.