Characterization of the emission of particles larger than 10 nm in the exhaust of modern gasoline and CNG light duty vehicles

Abstract Current particle number (PN) emission limits set by regulation, involve counted particles with a dimension >23 nm. The measurement procedure is specified and involves the dilution of exhaust gas in so-called constant volume sampling (CVS) device. Research efforts are concentrating further development existing techniques order to capture smaller down 10 nm, given their higher health threatening potential. In present study, six state art, Euro 6, gasoline vehicles addition, one compressed natural (CNG) light duty vehicle, have been measured on chassis dynamometer during different test cycles. Three lines used, two parallel at CVS, counting >23 nm third directly tailpipe vehicle. results allow detailed evaluation emitted PNs. differences emissions patterns direct fuel injection (DI) multi point port (MPI) could be identified. During cold starts, separated distinctive size classes obtain relevant number-size distributions. Counting >10 nm resulted roughly doubling PN respect those when This relation holds for all examined driving PNs CVS where significantly than tailpipe, especially capturing also particles. identified contributing increase registered numbers cycle parts no or very low engine emissions. Lowest combination CNG between DI MPI lower expected from previous studies. While emit more start, larger high loads. smallest evident. increased rated power displacement ratio modern engines, based current “downsizing” trend, shows good correlation