Abstract Ultrafine particles (UFP, diameter < 100nm), which dominate diesel engine emissions, are known to cause adverse health effects in humans (aggravated asthma, decreased lung function, irregular heartbeat, and nonfatal heart attacks) (EPA, 06JUL2011). Previous studies have shown changes in both particle mass (PM) and particle number (PN) emissions when diesel engines are fueled by different blends of biodiesel and petrodiesel as opposed to neat petrodiesel.
The objective of this research was to quantify the differences in particle number (PN) emissions for a single light-duty diesel engine operating on 5 different fuel blends (B0, B10, B20, B50, and B100). PN distributions were measured from a 1.9L Volkswagen diesel engine coupled to an eddy current dynamometer in real-time for neat and blended petro-diesel and ASTM grade waste cooking oil biodiesel with a TSI Engine Exhaust Particle Sizer (EEPS, 32 channels, 5.6-560nm range). The engine was run through a transient drive cycle developed from on-road data collected from a Volkswagen TDi vehicle while it was operated through urban driving conditions in the New England landscape.
The data collected by the EEPS in the UFP range show an increase compared to petrodiesel in particle number throughout the UFP size range for B10, a decrease UFP throughout the size range for B20, followed by subsequent increases of UFP for B50 and B100 below 60nm. This leads to changes in total UFP emissions by factors of 2, 0.85, 1.8, and 3 relative to petrodiesel for B10, B20, B50, and B100 respectfully. In addition to investigating possible mechanisms that could cause such a relationship, the effect of engine operating conditions on UFP emissions were examined.