Abstract
A novel technique that focuses on light scattering from soot aggregates is proposed to simultaneously measure size and concentration of soot aggregates in diesel exhaust. A vertically polarized laser beam illuminates a small exhaust jet containing soot particles and the scattered light is detected at two scattering angles from which the size and soot mass concentration are calculated using the soot aggregate scattering theory that is based on Guinier law. The performance of the instrument built is assessed by comparative experiments with the light extinction method. Using the scattering method, soot mass concentrations before and after a diesel particulate filter are simultaneously measured to allow calculation of transient filtration efficiency that characterizes the particulate filter performance. Another application is demonstrated in which soot loading in a filter is estimated from measurements of scattering intensity and the intake air flow rate.
