Diesel exhaust nanoparticles characterization by multiwavelength techniques, laser induced incandescence and ELPI

Two different optical techniques for detection, sizing and counting nanoparticles were applied to undiluted exhaust from 16 v - 1900 cc Common-Rail diesel engine upstream and downstream of a Catalyzed Diesel Particulate Filter (CDPF): Broadband Ultraviolet-Visible Extinction and Scattering Spectroscopy (BUVESS) and Laser-Induced Incandescence (LII). They are powerful "in situ" and non-intrusive techniques; they are able to measure mass concentration and size of particles, considering their chemical properties. BUVESS overcomes the intrinsic limitations of single wavelength techniques because it takes advantage of data at several wavelengths to retrieve primary particle size distribution. LII measures mean size of primary particles with a large dynamic range, not limited by aggregate size and by complex retrieving procedure. In this work, different engine operating conditions were selected in order to evaluate dynamic range of the techniques with respect to the low-mass particulate emission. The optical results were compared with those obtained by conventional methods like sampling of Particulate Matter for mass concentration and Electrical Low Pressure Impactor (ELPI) for sizing.