Kevin A. Whitney

Emission Rates and Comparative Chemical Composition from Selected In-Use Diesel and Gasoline-Fueled Vehicles

Abstract Emission samples for toxicity testing and detailed chemical characterization were collected from a variety of gasoline- and diesel-fueled in-use vehicles operated on the Unified Driving Cycle on a chassis dynamometer. Gasoline vehicles included normal particle mass (particulate matter [PM]) emitters (tested at 72 and 30°F), “black” and “white” smokers, and a new-technology vehicle (tested at 72 °F). Diesel vehicles included current-technology vehicles (tested at 72 and 30°F) and a high PM emitter. Total PM emission rates ranged from below 3 mg/mi up to more than 700 mg/mi for the white smoker gasoline vehicle. Emission rates of organic and elemental carbon (OC/EC), elements (metals and associated analytes), ions, and a variety of particulate and semi-volatile organic compounds (polycyclic aromatic hydrocarbons [PAH], nitro-PAH, oxy-PAH, hopanes, and steranes) are reported for these vehicles. Speciated organic analysis also was conducted on the fuels and lube oils obtained from these vehicles after the emissions testing. The compositions of emissions were highly dependent on the fuel type (gasoline vs. diesel), the state of vehicle maintenance (low, average, or high emitters; white or black smokers), and ambient conditions (i.e., temperature) of the vehicles. Fuel and oil analyses from these vehicles showed that oil served as a repository for combustion byproducts (e.g., PAH), and oil-burning gasoline vehicles emitted PAH in higher concentrations than did other vehicles. These PAH emissions matched the PAH compositions observed in oil.

Relationship between composition and toxicity of motor vehicle emission samples.

In this study we investigated the statistical relationship between particle and semivolatile organic chemical constituents in gasoline and diesel vehicle exhaust samples, and toxicity as measured by inflammation and tissue damage in rat lungs and mutagenicity in bacteria. Exhaust samples were collected from “normal” and “high-emitting” gasoline and diesel light-duty vehicles. We employed a combination of principal component analysis (PCA) and partial least-squares regression (PLS; also known as projection to latent structures) to evaluate the relationships between chemical composition of vehicle exhaust and toxicity. The PLS analysis revealed the chemical constituents covarying most strongly with toxicity and produced models predicting the relative toxicity of the samples with good accuracy. The specific nitro-polycyclic aromatic hydrocarbons important for mutagenicity were the same chemicals that have been implicated by decades of bioassay-directed fractionation. These chemicals were not related to lung toxicity, which was associated with organic carbon and select organic compounds that are present in lubricating oil. The results demonstrate the utility of the PCA/PLS approach for evaluating composition–response relationships in complex mixture exposures and also provide a starting point for confirming causality and determining the mechanisms of the lung effects.

Emissions Comparison of Alternative Fuels in an Advanced Automotive Diesel Engine

Exhaust emissions mappings were conducted for six alternative diesel fuels in a Daimler-Benz (DB) OM6l1 diesel engine. The OM6l 1 engine is a 2.2L, direct-injection diesel with a Bosch, high-pressure, common-rail, fuel-injection system. The engine design closely matches the specifications of the Partnership for a New Generation Vehicle (PNGV) target compression-ignition engine. Triplicate 13-mode, steady-state test sequences were performed for each fuel, with a 2-D control fuel serving as the baseline. No adjustments were made to the engine to compensate for any performance differences resulting from fuel property variations.

Comparative Toxicity of Gasoline and Diesel Engine Emissions

Better information on the comparative toxicity of airborne emissions from different types of engines is needed to guide the development of heavy vehicle engine, fuel, lubricant, and exhaust after-treatment technologies, and to place the health hazards of current heavy vehicle emissions in their proper perspective. To help fill this information gap, samples of vehicle exhaust particles and semi-volatile organic compounds (SVOC) were collected and analyzed. The biological activity of the combined particle-SVOC samples is being tested using standardized toxicity assays. This report provides an update on the design of experiments to test the relative toxicity of engine emissions from various sources.

An Investigation of Sample Bag Hydrocarbon Emissions and Carbon Dioxide Permeation Properties

The equipment for collecting dilute exhaust samples involves the use of bag materials (i.e., Tedlar®) that emit hydrocarbons that contaminate samples. This study identifies a list of materials and tre tments to produce bags that reduce contamination. Based on the average emission rates, baked Tedlar®, Capran® treated with alumina deposition, supercritical CO 2 extracted Kynar® and supercritical CO 2 extracted Teflon NXT are capable of achieving the target hydrocarbon emission rate of less than 15 ppbC per 30 minutes. CO 2 permeation tests were also performed. Tedlar, Capran, Kynar and Teflon NXT showed comparable average permeation rates. Based on the criteria of HC emission performance, changes in measured CO 2 concentration, ease of sealing, and ease of surface treatment, none of the four materials could be distinguished from one another. Additional information from further testing would need to be added to the results of this study in order to choose a single optimum sample bag material for vehicle emission testing.

Development of a dedicated ethanol ultra-low-emissions vehicle (ULEV): Phase 3 report

The objective of the 3.5 year project discussed in this report was to develop a commercially competitive vehicle powered by ethanol (or an ethanol blend) that can meet California`s Ultra Low Emissions Vehicle (ULEV) standards and equivalent Corporate Average Fuel Economy (CAFE) energy efficiency for a light duty passenger car application. This particular report summarizes the third phase of the project, which lasted 12 months. Emissions tests were conducted with advanced after-treatment devices on one of the two, almost identical, test vehicles, a 1993 Ford Taurus flexible fuel vehicle. The report also covers tests on the engine removed from the second Taurus vehicle. This engine was modified for an increased compression ratio, fitted with air assist injectors, and included an advanced engine control system with model-based control.