Analyses of Mechanism on Roadside Pollution by On-Board Emissions Measurement System

Abstract

An on-board measurement system that can simultaneously obtain such information as road infrastructure, traffic conditions, driver's operations, vehicle running conditions, and exhaust mass emissions was installed in a light duty freight vehicle with an EGR system and in a minivan without an EGR system. In order to analyze the mechanism of roadside pollution caused by vehicles, road tests were carried out in real traffic conditions. The light duty freight vehicle showed intensive NOx pollution at the roadside in a vehicle start, in which the EGR rate was low, but it was effective to reduce NOx mass emissions at low speed running in traffic jams where the EGR rate was rather high. In the case of the minivan, intensive NOx pollution was observed in low speed running such as in traffic jams. The reduction of NOx during vehicle starts is important for vehicles with an EGR system to reduce intensive NOx pollution at roadsides.EGR system and in a minivan without an EGR system, and examined factors of intensive NOx pollution such as infrastructures of roads, traffic environment, and vehicle motion by measuring instantaneous NOx mass emissions. Thus, NOx pollution at local roadsides was analyzed from the aspects of vehicle motion and engine operation, by studying the relation of instantaneous vehicle speeds and instantaneous NOx emissions factors, the relation of instantaneous CO 2 and NOx mass emissions, and the relation of engine speed, engine torque, and instantaneous NOx emissions factors.