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A 1.9L turbocharged direct-injection engine representing a model year 1998-2003 Volkswagen vehicle, equipped with the OEM diesel oxidation catalyst (DOC) and exhaust gas recirculation (EGR), was tested on an eddy-current engine dynamometer with a critical flow venturi-constant volume sampling system (CFV-CVS). The engine was operated over three steady-state modes: 1600 rev/min at 54 Nm; 1800 rev/min at 81 Nm; and 2000 rev/min at 98 Nm. Commercially available ultra-low sulfur diesel fuel (≺15 ppm S) was splash-blended with fatty acid methyl ester biodiesels derived from three different feedstocks: canola, soy, and tallow/waste fry oil. Test blend levels included: 0%, 2%, 5%, 20%, 50%, and 100% biodiesel for each feedstock.

The recent tightening of emission standards for new heavy duty engines has lead to the development and implementation of alternative fuel engines, particularly for urban transit bus applications. Alternative fuels are intended to offer a potential emissions benefit with regards to the regulated emissions, and especially the particulate matter, which has received the greatest degree of regulatory action. However, the entire composition of the engine emissions should be considered when evaluating the environmental benefits of these new fuels, and also the continued performance of these engines in actual fleet service. In this study the exhaust emissions from methanol, ethanol, and diesel - powered buses were determined during transient operation of the vehicles on a heavy duty chassis dynamometer. The tests of the alcohol fuelled buses, and a control diesel bus were conducted as the buses accumulated mileage in revenue generating service.

This paper presents the emissions testing results of various heavy duty engines and vehicles with and without retrofitted diesel oxidation catalyst technology. 1987 Cummins L10 and 1991 DDC 6V92TA DDECII engine results over the U.S. Heavy Duty Transient Test are presented for comparison to chassis test results. The vehicles in this study include two urban buses, two school buses and three heavy duty trucks. The Central Business District, New York Bus and New York Composite urban driving cycles have been used to evaluate baseline emissions and the catalyst performance on a heavy duty chassis dynamometer. The results demonstrate that 25-45% particulate reduction is readily achievable on a wide variety of heavy duty vehicles. Significant carbon monoxide and hydrocarbon reductions were also observed.

As more stringent vehicle emission standards are introduced worldwide, there is an increased need to provide a thorough assessment of the environmental impact of alternative fuels. With the advent of CNG as a viable transportation fuel, the development of advanced computer controlled fuel delivery systems is imperative in order to ensure acceptable emission performance. At present, the majority of light and medium duty engines operating on natural gas are primarily gasoline automotive engines which have been retrofitted to allow for the use of CNG. The Mobile Sources Emissions Division of Environment Canada and the Canadian Gas Association have conducted a joint test program in order to develop a database of exhaust emissions from vehicles typically converted for operation on either gasoline or natural gas at various operating temperatures.