Emission factor development for light-duty vehicles based on real-world emissions using emission map-based simulation

Abstract

Transport emission factors describe pollutant emissions of vehicles by relating with vehicle activities such as traveled distance. Accurate emission factors are essential for estimating transport emission and making better decision to address air pollution and climate change. In this paper, map-based simulations were used to develop emission factors of CO₂, NOx and CO based on real-world emissions, as were measured with a Portable Emission Measurement System (PEMS). Vehicle dynamic-based simulation model were used to calculated emission factors using the emission maps as input data, which were developed from real-world emissions. We developed emission factors by fuel type, emission regulation, aftertreatment system and engine displacement. Among various factors, the introduction of Real Driving Emission (RDE) regulation had the greatest influence on the emission factor. For diesel LDVs, NOx and CO emission factors of the Euro 6 d-temp vehicles, which have been applied RDE regulation for the first time, were lower than those of the Euro 5 and Euro 6 b/c vehicles. However, the CO₂ emission factors of the Euro 6 d-temp was higher than those of the Euro 5 and Euro 6 b/c vehicles. In addition to calculating emission factors, the proposed methodology provides an improved process that simulate vehicle emissions based on real-world emissions.

Keywords: Emission factor; Emission map; Longitudinal vehicle dynamics; Real-world emission; Simulation model.