Search Results

Diesel particulate filters (DPFs) were loaded and fractured to determine the time effect of loading, and loading differences between ULSD and a B20 biodiesel blend. DPFs were loaded in parallel for exposure times of 1, 2, 5 and 10 hours. Scanning electron microscopy and Raman spectroscopy were used to visualize loading and analyze the carbon structure of particulates on the filter substrate. Images of the soot cake were captured and the ‘pore-bridge’ was identified as an important feature in DPF functionality. Raman analysis revealed that the nature of the carbon soot structure did not become increasingly graphitic with loading time; the soot cake was observed to be a disordered, variable feature.

An off-road direct injection diesel engine equipped with a catalyzed diesel particulate filter (DPF) was subject to two sets of experiments in which two fuels, ultra low sulfur diesel (ULSD) and 20 vol. % biodiesel blend (B20) were compared. In the first set of experiments lubricant oil consumption was measured by sulfur tracing. In the second set of experiments nanoparticle formation downstream of the DPF was assessed. It was found that number concentration of nanoparticles released from the catalyzed DPF depends on fuel type and on engine operating condition and hence the onset of filter regeneration. For low soot loading times B20 fueling produces lower number concentrations, whereas longer soot loading times produce lower number concentrations with ULSD fueling.

Particulate matter emissions from gasoline direct injection engines are a concern due to the health effects associated with ultrafine particles. This experimental study investigated sources of particulate matter emissions variability observed in previous tests and also examined the effect of ethanol content in gasoline on particle number (PN) concentrations and particle mass (PM) emissions. FTIR measurements of gas phase hydrocarbon emissions provided evidence that changes in fuel composition were responsible for the variability. Exhaust emissions of toluene and ethanol correlated positively with emitted PN concentrations, while emissions of isobutylene correlated negatively. Exhaust emissions of toluene and isobutylene were interpreted as markers of gasoline aromatic content and gasoline volatility respectively.

Crevices in the combustion chamber are the main source of hydrocarbon (HC) emissions from spark ignition (SI) engines fuelled by natural gas (NG). Instantaneous in-cylinder and engine exhaust port HC concentrations were measured simultaneously using a Cambustion HFR400 fast response flame ionization detector (FRFID) concentrated on the post-flame period. The raw data was reconstructed to account for variation in the FFRID sample transit time and time constant due to fluctuating in-cylinder pressure. HC concentration development during the post-flame period is discussed. Comparison is made of the post-flame in-cylinder and exhaust port HC concentrations under different engine operating conditions, which gives a better understanding of the mechanism by which HC emissions form from crevices in SI engines.

Biodiesel and other renewable fuels are of interest due to their impact on energy supplies as well as their potential for carbon emissions reductions. Waste animal fats from meat processing facilities, which would otherwise be sent to landfill, have been proposed as a feedstock for biodiesel production. Emissions from biodiesel fuels derived from vegetable oils have undergone intense study, but there remains a lack of data describing the emissions implications of using animal fats as a biodiesel feedstock. In this study, emissions of NOx, unburned hydrocarbons and particulate matter from a compression ignition engine were examined. The particulate matter emissions were characterized using gravimetric analysis, elemental carbon analysis and transmission electron microscopy. The emissions from an animal fat derived B20 blend were compared to those from petroleum diesel and a soy derived B20 blend.