AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
An Aerosol Detection Technique for Diesel Fuel Contaminants
KAI XIAO, Chenxing Pei, Jacob Swanson, David Kittelson, David Y. H. Pui, University of Minnesota
Abstract Number: 291 Working Group: Instrumentation and Methods
Abstract High Pressure Common Rail injection systems are designed to increase combustion efficiency and to reduce particle emissions for modern Diesel engines. The rising pressure and reduced clearances make the system more sensitive to contaminants which may cause a higher injector leakage and increased emissions. These issues have raised the need of more efficient fuel filters and a fast and reliable monitoring method for small contaminants in the fuel. The most used way to measure the concentration of liquid-borne particles is based on direct optical measurements of particles using a liquid particle counter. A limitation to easily improving this technique is due to the fact that contaminants in the fuel have similar refractive index as the fuel itself.
An aerosol-based detection technique was developed to characterize particle contaminants in Diesel fuel in the size range of 0.5-4μm. By transforming the liquid-borne particles in the fuel to airborne with a constant output atomizer, the background is changed from relatively opaque Diesel fuel to air. With the help of a catalytic stripper, fuel droplets are removed and particles are detected by the aerosol instrument downstream. The size range of aerosol instrument enables a lower size limit as small as 0.5 µm. Filtered Diesel fuel seeded with monodisperse silica particles has been used for calibration purposes. The sizing tests with three different size (0.73, 1.8 and 3.6 µm) seed particles indicate that the system is able to precisely (measured diameter within 5% of manufacturer’s value) determine the size of the contaminants in the fuel. In concentration tests, the air-borne and liquid-borne particle concentrations have been found to follow a linear relationship for all three sizes, although different sizes have different slopes. A compensation procedure was proposed to account for this difference. Using this procedure, liquid-borne concentration could be predicted from the measured airborne concentration.