Solutions for enhancing remote sensing high emitter vehicle screening procedures

The research presented here combines a carbon balance with fuel consumption estimates to convert emissions measured by remote sensing devices (RSD) from concentration to mass. In estimating vehicle fuel consumption rates, the VT-Micro model and a Vehicle Specific Power (VSP)-based model (the PERE model) are considered and compared. The results of the comparison demonstrate that both of the VT-Micro and PERE models provide reliable fuel consumption estimates (R² of 90% and higher for a 1993 Honda Accord with a 2.4L engine). RSDs capture only an instantaneous snapshot of a vehicle´s emissions, and how this single point measurement might be related to the vehicle´s overall emission status, to our knowledge, has not yet been mechanistically assessed. For the above sample vehicle, the in-laboratory mass emissions measured over an IM240 driving cycle identified the sample vehicle as a normal emitter in 100%, 97%, and 89% of the second-by-second measurements for HC, CO, and NO_X emissions, respectively. The estimated mass emissions based on concentration measurements and the modeled fuel consumption rate yielded normal emitter results in 100%, 97%, and 88% of the measurements. These results suggest a 100%, 100%, and 99% success rate relative to the results from in-laboratory measured emissions. The study clearly demonstrates that the proposed procedure works well in converting concentration measurements to mass emissions and can be applicable in the screening of HEVs and normal emitting vehicles for several vehicle types such as sedans, station wagons, full-size vans, mini vans, pickup trucks, and SUVs.