AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
An Aerosol Detection Technique for Diesel Fuel Contaminants
KAI XIAO, Jacob Swanson, Lin Li, Tsz Yan Ling, David Kittelson, David Pui, University of Minnesota
Abstract Number: 238 Working Group: Instrumentation and Methods
Abstract The High Pressure Common Rail (HPCR) fuel injection systems are designed to increase combustion efficiency and reduce particle emissions for modern Diesel engines. However, these systems are more sensitive to particle contaminants in the Diesel fuel due to higher pressures and smaller clearances. Damage to the injection system can be caused by submicron particles. However, the current detection standard only regulates particles larger than 4 microns, leaving an uncertainty in the concentration of smaller particles in the supply fuel. This standard is based on direct optical measurements of particles using a liquid particle counter. A limitation to easily extend this technique while retaining general procedure is due to the fact that contaminants in the fuel have similar refractive index as the fuel itself, which makes it difficult to distinguish smaller particles from the fuel.
A new aerosol-based detection technique was developed to characterize particle contaminants in Diesel fuel. The Diesel fuel, diluted by highly volatile hexane, is vaporized by a constant output atomizer. The atomized Diesel fuel was passed through a catalytic stripper that was used to separate the solid contaminants from the fuel and diluent. A water trap and a diffusion dryer were connected after the catalytic stripper to collect the generated water droplets and vapor. Remaining solid particles were measured using an aerodynamic particle sizer (APS), which provides information on the contaminant particles’ size distribution and total concentration. This technique is an effective means to transfer the liquid-borne particles into the gas phase and thus increase the distinction between particles and the background. Results reported include a comparison between this method and the current technique as well as fuel filter sample analysis. Results showed that the lower size limit of the aerosolization method can go down to as small as 0.5 microns.