Evaluating Real Driving Emissions of Compressed Natural Gas Taxis in Chongqing, China—A Typical Mountain Cities
Wei Hu,
Linfeng Duan,
Min Tang,
Rui Yuan,
Gaiyan Lv,
Pingjiang Lv,
Zhenliang Li,
Ling Li,
Hualong Xu,
Jiajia Ding,
Dan Zhang
Affiliations
Wei Hu
Chongqing Key Laboratory of Green and Low-Carbon the Evaluation and Control of Green Low-Carbon Emissions from Mobile Sources, Chongqing Research Academy of Eco-Environmental Sciences, Chongqing 401147, China
Linfeng Duan
Key Laboratory of the Three: Gorges·Reservoir Region’s Eco-Environment, Ministry of Education, Chongqing University, Chongqing 400045, China
Min Tang
Chongqing Ecological and Environmental Monitoring Center, Chongqing 401122, China
Rui Yuan
Chongqing Key Laboratory of Green and Low-Carbon the Evaluation and Control of Green Low-Carbon Emissions from Mobile Sources, Chongqing Research Academy of Eco-Environmental Sciences, Chongqing 401147, China
Gaiyan Lv
Chongqing Key Laboratory of Green and Low-Carbon the Evaluation and Control of Green Low-Carbon Emissions from Mobile Sources, Chongqing Research Academy of Eco-Environmental Sciences, Chongqing 401147, China
Pingjiang Lv
Chongqing Key Laboratory of Green and Low-Carbon the Evaluation and Control of Green Low-Carbon Emissions from Mobile Sources, Chongqing Research Academy of Eco-Environmental Sciences, Chongqing 401147, China
Zhenliang Li
Chongqing Key Laboratory of Green and Low-Carbon the Evaluation and Control of Green Low-Carbon Emissions from Mobile Sources, Chongqing Research Academy of Eco-Environmental Sciences, Chongqing 401147, China
Ling Li
Chongqing Key Laboratory of Green and Low-Carbon the Evaluation and Control of Green Low-Carbon Emissions from Mobile Sources, Chongqing Research Academy of Eco-Environmental Sciences, Chongqing 401147, China
Hualong Xu
China Automotive Engineering Research Institute Co., Ltd., Chongqing 401122, China
Jiajia Ding
Chongqing Key Laboratory of Green and Low-Carbon the Evaluation and Control of Green Low-Carbon Emissions from Mobile Sources, Chongqing Research Academy of Eco-Environmental Sciences, Chongqing 401147, China
Dan Zhang
Chongqing Key Laboratory of Green and Low-Carbon the Evaluation and Control of Green Low-Carbon Emissions from Mobile Sources, Chongqing Research Academy of Eco-Environmental Sciences, Chongqing 401147, China
Compressed natural gas (CNG) taxis represent the most ubiquitous and dynamically active passenger vehicles in urban settings. The pollutant emission characteristics of in-use CNG taxis driving on a typical mountain city before and after three-way catalyst (TWC) replacement was examined using a modular on-board portable emissions measurement system (PEMS), the OBS-ONE developed by Horiba. The results showed that the exhaust NO of CNG taxis equipped with deactivation TWC exceeded the emission limits, even higher than gasoline vehicles. The high emission rate of CNG taxis is mainly concentrated on road slopes between a 2% and 6% gradient and a deceleration rate in the interval of [0.5, 4], respectively, which results in higher emissions from CNG taxis traveling in the mountain city of Chongqing than other cities and vehicles. Moreover, the pollutant emission rates of the in-use CNG taxis were highly correlated with the velocity and the vehicle specific power (VSP). After a new TWC replacement, the emission factors of carbon monoxide (CO), total hydrocarbons (THC), nitrogen oxides (NOx), and particle number (PN) decreased by 85.21–89.11%, 68.71–85.49%, 60.91–81.11%, and 62.26–68.39%, respectively. Our results will provide guidance for urban environments to carry out the comprehensive management of in-use vehicles and emphasize the importance of TWC replacement for CNG taxis.
