In-situ Laser Induced Incandescence technique for measurement of full stream fast transient soot emissions in real-time

The Laser Induced Incandescence technique (LII) is an emerging optical method for the reliable spatially and temporally resolved measurement of soot concentration and potentially for monitoring primary soot particle size. Due to its origin, this method appears to be suitable for the measurement of fast transient soot emissions from Diesel engines, which form the main fraction of total emissions during standardised test cycles. Current existing commercial LII devices require modifications in the exhaust gas flow, dilution, and measuring with a partial stream in a preconditioned cell. The results from the development of a single window access in-situ LII setup for rapid measurement of soot emission during the combustion process from a Diesel production engine, suitable for direct full stream, measurements in the tail-pipe without the need for dilution or a sampling cell are presented here. Furthermore, the issue of the optical window cleaning, background incandescence due to the laser - tailpipe interaction and possible suppression of disrupted emission by means of time delay constant is addressed. The obtained and corrected in-situ LII results are further compared to commercially available devices for the measurement of soot emissions. Static and dynamic emission tests have been performed in order to demonstrate the viability and applicability of proposed single access optical probe for full stream fast transient soot emission measurement in real-time.