Biodiesel is currently used by a relatively large number of mining operations in the U.S. to control exposures of underground miners to aerosols emitted by diesel-powered vehicles. The National Institute for Occupational Safety and Health (NIOSH) conducted a study with the objective of quantifying and characterizing the effects of soy derived fatty acid methyl ester (FAME) biodiesel fuels on physical and chemical properties of aerosols emitted by diesel engines.
The effects of two biodiesel blends (B20, B50) and neat biodiesel (B100) were qualitatively compared with the corresponding effects of neat ultralow sulfur diesel (ULSD) fuel. The experimental work was executed at the diesel laboratory at the NIOSH Office of Mine Safety and Health Research using naturally-aspirated mechanically-controlled Isuzu C240 engine equipped with diesel oxidation catalytic converter (DOC) coupled to eddy-current dynamometer. The measurements and sampling was done for four steady-state engine operating conditions. The aerosol measurements and samplings were performed in exhaust diluted in a two-stage partial flow dilution system. Number concentrations and size distribution of aerosols in diluted exhaust were continuously measured using a scanning mobility particle sizer spectrometer. The concentrations of elemental (EC) and total carbon (TC) in diluted exhaust were assessed using the results of thermal optical analysis performed on the samples collected on quartz fiber filters. The detailed speciation was done on particle bound and semi-volatile species using gas chromatography mass spectrometry. The effects of tested fuels on physical and chemical properties of aerosols were found to be strongly influenced by engine operating conditions and fuels. Under the majority of conditions, the biodiesel?containing fuels produced lower mass and number concentrations of aerosols.
The count geometric mean diameter of emitted aerosols was found to decrease with an increase in biodiesel content in the fuels. For all test conditions, the engine emitted less EC and TC when fueled with fuels containing biodiesel (B20, B50, and B100) than with ULSD. However, the reductions in concentrations and correlation between biodiesel content in the fuels and reductions were found to be strongly dependent on engine operating conditions. The detailed chemical speciation showed major impact of fuels on the chemical composition of particle bound and semi-volatile organic compounds.
Last Updated: 19/05/2020 01:10:47pm