Abstract
On-road vehicle tests of three diesel trucks were conducted by a portable emission measurement system (PEMS) in Chengdu, China. SEMTECH-ECOSTAR provided by Sensors, Inc and MI2, an emissions measuring instrument powered by the Pegasor Particulate Sensor (PPS) were employed to detect gaseous and particle emissions during the tests. The impacts of speed and acceleration on emissions were analyzed. The average NOx emission factors of the heavy duty diesel truck (HDDT), medium-duty diesel truck (MDDT), light duty diesel truck (LDDT) were 7.29, 5.29 and 5.53 g/km, all of which were in excess of their emission limits. The particle emission factors were 0.60, 0.30 and 0.14 g/km, generally higher than the results for similar reported in the previous studies. Both gaseous and particle emission exhibit significant correlations with the change in vehicle speed, acceleration and power demand. The highest emission for each vehicle were generally found in high-VSP. High engine power caused by aggressive driving or heavy load is the main factor of high emissions for the vehicles in real-world situation. Introduction Due to their high toxicity, adverse health effects and their abundance near the roads, particularly in urban areas, diesel emissions are of high concern in recent decades. Gaseous emissions from vehicles, including NOx, THC, and CO, have been as the primary precursors of photochemical smog. Fine particles have attracted increasing attention due to their strong impact on aerosol formation[1, 2] . PM and NOx emissions from vehicles account for about 50% of emission inventories[3]. This study focuses on the real-world operating condition and emission characteristics of diesel trucks for logistics transportation. This research was motivated by the recognition that in most Chinese cities, diesel trucks are the most widely used logistics transportation. The diesel trucks are the major contributors to the urban environmental pollution. To better understand the emission characteristics of diesel vehicles, many measurements have been conducted in recent years. Emissions measurements for diesel vehicles have been made using chassis and engine dynamometer, remote sensing, tunnel studies and on-board measurements (PEMS)[4, 5]. PEMS has been developed as an effective and practical method to quantify vehicle emission levels with real-world vehicle activities [6, 7]. Previous studies have conducted numerous tests to measure the emissions from different type vehicles using PEMS, which revealed that vehicle emissions are strongly related with driving cycle, fuel quality, and after-treatment equipment[8, 9]. PEMS testings have also been carried out in Chinese cities [10-12]. These studies have produced many results for in-use vehicle emission characteristics and have laid a foundation for policy-making in vehicle pollution control in China. A few works have studied impacts of vehicle speed and acceleration on vehicle emissions. For the time being, most published studies on real-world vehicle emissions focuses on 2014 International Conference on Social Science (ICSS 2014) © 2014. The authors Published by Atlantis Press 171 automobiles[10, 13], however very little work have been published on urban logistics transportation vehicles. The purpose of the current research was to survey correlation of pollutant emissions and driving conditions. Three Euro III emission level trucks were chosen for this survey, because most of Chengdu trucks are using this type engine after renewed in the year 2008. In this study, high-precision vehicle emissions testing system (PEMS) was used to get the logistics vehicles emissions data under actual operating conditions in Chengdu, calculate the emission factor, and analyze such vehicles emission characteristics. Materials and methods Tested trucks The on-road emission tests were conducted in 2014 in Chengdu. Several vehicle types were selected in this study, including a heavy duty diesel truck (HDDT), medium-duty diesel truck(MDDT), light duty diesel truck(LDDT),. The specifications of the test vehicles were listed in Table 1. Each vehicle type satisfies the latest emission standards in Chengdu. The diesel fuel used in the test were obtained directly from the petrol station. The fuel quality met the requirements of the local standard equivalent to Euro 3.The sulfur content of diesel fuel should be controlled below 0.035%. Table 1 Test vehicle specifications. Vehicle type heavy duty diesel truck medium-duty diesel truck light duty diesel truck Fuel type Diesel Diesel Diesel GVWR (kg) 16000 8100 4320 Engine type Diesel engine Diesel engine Diesel engine Displacement (L) 3.9 2.77 2.77 Emission standard Euro 3 Euro 3 Euro 3 Model year 2011 201
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