Instrumentation for the remote-sensing of PM and NOx from diesel vehicles

A team of researchers at Oak Ridge National Laboratory is developing prototype instruments to remotely and non-intrusively measure the NO _x and particulate matter (PM) emissions from heavy-duty trucks as they drive down the road. The instruments employ an ultraviolet (UV) absorption method to measure NO _x and a modified LIDAR method to measure PM concentrations in the exhaust plumes of moving trucks. The instruments have been modified since they were last reported on in 2003 to include array detection for the UV and a monostatic optical design for the LIDAR. The hardware cost for the prototypes is low, less than $10,000 per instrument, and the response time will allow multiple measurements of exhaust from a moving vehicle. The results of both laboratory and field experiments using various aerosols and diesel vehicles is reported. Chassis lab experiments were performed using a light-duty diesel vehicle and road testing was performed using the same light-duty diesel vehicle and two heavy-duty diesel vehicles. The instruments described here measure the concentration of emissions in air while emissions data are more typically provided in terms of grams-per-mile. The technique used to get from concentration to grams-per-mile is acoustic rather than optical and is described in other publications.