Characteristics of Engine Emissions from Different Biodiesel Blends

Engine exhaust characteristics from two different biodiesel blends, formulated from soy and animal fat biodiesel blended with ultra-low sulphur diesel, were tested during two different test programs with similar operating conditions. Engine exhaust was measured in real-time for nitrogen oxides, total hydrocarbons, particle-bound polyaromatic hydrocarbons, and particle size distribution. Diesel particulate matter was collected on filters and subsequently analyzed for organic carbon, elemental carbon, soluble organic fraction, cations, and anions. The use of biodiesel was found to increase nitrogen oxide emissions, but decrease total hydrocarbons and particulate matter emissions. The most significant impact on emissions was the difference between the engine operating conditions rather than the fuel type. Minor differences were found between the soy and animal fat biodiesel blends through speciation of the diesel particulate matter.