Evaluating Nitrogen Oxides and Ultrafine Particulate Matter Emission Features of Urban Bus Based on Real-World Driving Conditions in the Yangtze River Delta Area, China

• Main Authors: Dengguo Liu, Diming Lou, Juan Liu, Liang Fang, Weiming Huang
• Format: Article
• Language: English
• Published: MDPI AG 2018-06-01
• Series: Sustainability
• Subjects: ultrafine particulate matter; NOx; PEMS; emission factor; real-world driving; Yangtze River Delta
• Online Access: http://www.mdpi.com/2071-1050/10/6/2051

A Portable Emission Measurement System was used in this study to evaluate the exhaust emission characteristics of nitrogen oxides (NOx), ultrafine particulate matter (PM), and ultrafine particulate number (PN) from buses in the Yangtze River Delta, China. Results showed that NOx emission factor (unit: g·km−1) increased from 5.0 to 19.1, and PM emission factor (unit: g·km−1) increased from 0.001 to 0.189. A nonlinear model was established based on scientific statistical method, which showed that NOx and PM emission factors significantly decreased with speed increasing. The model also showed a “long tail effect” of NOx and PM emission factors beyond 30 km·h−1. Furthermore, hybrid bus exhausted less NOx, PM, and PN emissions compared to conventional bus in the acceleration condition. Exhaust rates of NOx, PM and PN emissions (unit: g·s−1) increased with speed increasing under steady state driving condition, while PN emissions commonly showed a unimodal distribution at the speed of 20 km·h−1.