Exhaust Emissions Characteristics of Scooters on the Real World in Taiwan

Copyright 2013 SAE Japan and Copyright 2013 SAE International JSAE 20139050 / SAE 2013-32-9050 Exhaust Emissions Characteristics of Scooters on the Real World in Taiwan Su, Kao-Chun 1, Chuang, Chih-Wei 1 1 Deputy Engineer; Automotive Research & Testing Center Chen, Hsin-Yi 2, Pei-Chang Wen 3, Chen, Hsueh-Heng 4 2 Analyst; Chung-Hua Institution for Economic Research, 3 Research Fellow; Chung-Hua Institution for Economic Research 4 Assistant researcher; Chung-Hua Institution for Economic Research ABSTRACT Scooter is the most popular personal vehicle in Taiwan; however, it also causes serious air pollution, especially in big crowded cities. In traditional method, vehicle exhaust emissions are measured with specific driving cycle in laboratory, but the test results hardly reflect the authentic exhaust emission for real world driving and road conditions. In the recently, OBS (On-Board Emission Measurement System) is a technology which can be installed on vehicles to collect exhaust emissions instantaneously on different road condition and time. This paper uses OBS (developed by ARTC, Automotive Research & Testing Center) installed on testing scooters to collect instantaneous exhaust emissions on typical roads and time periods. The test results can be used to analyze the scooter running characteristics of emissions. INTRODUCTION With motor vehicle industry developing and economic growing rapidly, motor vehicle has become widely used. However exhaust emissions, the by-product of motor vehicle, have caused serious air pollution, especially in big and crowded cities. The motor vehicle exhaust emissions are composed of hydrocarbons (HCs), nitrogen oxides (NO x ), carbon monoxide (CO), and carbon dioxide (CO 2 ). Typically, motor vehicle exhaust emissions are measured and investigated in the laboratory using a dynamometer with standard (legislative) driving cycle. Although the ambient condition is under condition in the laboratory, the exhaust emissions data are still hard to reflect the real world road state because of very few speed fluctuations of standard driving cycle. In the real world road, many factors could affect the motor exhaust emissions, such as:traffic flows and signal plans, road level, and loads etc. Because of such complicated conditions, many studies start to focus on real world motor exhaust emissions for reflecting the authentic situation. The on-board system (OBS), a portable device which could be installed on motor vehicle, enables to collect emissions at any time and any location. In the past, because of the high price and technology development limitation, onboard system was not widely used. But now, it is available. The U.S. Environmental Protection Agency (EPA) is first to investigate emission by using on-board system in 1990. The on-board systems have also been developed, such as Clean Air Technologies International, Inc. (CATI), Sensors, Inc., Ford Motor Co., and Horiba. According on establishing the emissions on real world road conditions and on-board system technologies progress, there are many studies starting using on-board system to investigate the emissions characteristics. Qing et al. (2002) used on-board system which was installed on a van to describe the details of vehicle s driving pattern and emissions characteristic on real road condition of Tianjin. The study presents that the characteristic of driving pattern in Tianjin is very different from the characteristic of ECE-15 and FTP-75. Hawirko and Ceckel (2002) used an on-board system to record ambient conditions, driving behavior, vehicle operating parameters, fuel consumption and exhaust emissions. The results show that varying emission system anomalies were detected in virtually identical trips and were shown to have significant effect on the overall emission rates from the vehicle. Cheng et al. (2006) conducted on two heavy-duty diesel trucks on un-loaded and loaded condition by using a portable emission measurement system to measure real world vehicle emissions. The results indicate high fuel consumption and emission rates are concentrated on the high speed and acceleration areas of the speed-acceleration emission maps and the areas are much wider on loaded condition. All the studies listed above were conducted on passenger cars and light or heavy duty trucks, few study concerned the emission characteristics of scooter on real world. In Taiwan, scooter is the most popular personal vehicle. The amount of motor vehicle is about twenty millions, the scooter number is nearly 68% of the amount. Average rate of increment of scooter is 2.33% in the decade, from twelve million scooters in 2002 to fifteen million scooters in 2011. Although scooters bring the convenience, the exhaust emissions have become the main pollutant source, especially in big and crowded cities. This paper used an on-board measurement system to investigate the exhaust emission with two selected scooters during rush hours in different

road level. The factors that affect emissions characteristics are discussed. EXPERIMENTAL SET UP Testing Vehicle Two testing scooters which are common in Taiwan were selected to measure the exhaust emissions. The specific information is shown on Table 1. Table 1 Basic information of scooters for emission test Brand A type B type Engine Type single cylinder single Cylinder 4 stroke 4 stroke Dry Weight Amount (kg) 104 110 Displacement (cc) 124.6 124.6 Max. Horsepower (ps/rpm) 10.5/8,500 9.6/7,500 Max. Torque (kg-m/rpm) 1.0/6,500 0.98/6,500 Transmission System CVT CVT fuel supply system carburetor Fuel injection Bore*Stroke (mm) ψ52.4 57.8 ψ52.4 57.8 Fuel Capacity (L) 6.0 6.0 Homologation(R.O.C.) Phase 4 Phase 5 Used Age (year) 8 2.7 Mileage(km) 29,749 9,815 Testing Road Two different roads, rural arterials (C2-7-2) and urban streets (C5-10-2), were selected to enable a comparison of the tests results. On rural arterials, motorcycle is tested in low mixed traffic with traffic islands where two directions of traffic movements are divided by raised crossing islands of loads; on urban streets, motorcycle is tested in highly mixed traffic on urban streets without traffic islands where traffic movements are managed by pavement markings, shown on Figure 1 and Figure 2. Instrumentation The on-board measurement system used for collecting exhaust emission in this study is called OBS-584 which is manufactured and developed by ARTC. In the recently, most studies focus on the light, heavy duty trucks and passenger cars. With limited space and loads of scooter, the on-board instrument has to be slim to fit onto the scooter. OBS-584 is composed of MEXA 584L manufactured by HORIBA as an analyzer, a speed sensor, an engine speed sensor, a gas flow meter, a humidity/temp meter, a battery, a GPS, and a data collecting system. OBS-584 can be installed in 10 minutes in motor vehicle. The connections are reversible and do not require any modifications to the vehicle. MEXA 584L is a portable emission analyzer and well used to measure exhaust emission in idle state. This on-board system is a new instrument. To verify the precision and accuracy of MEXA 584L as an on board system analyzer for OBS-584, it was tested by the Emission & Fuel Economy Testing Laboratory of ARTC which has been certificated by Administrations of R.O.C., TUV-Nord and US EPA on either full or partial terms. The testing experiment conducted measuring exhaust emissions of a scooter with a 150 c.c. cylinder on the dynamometer equipment and by the OBS-584 respectively, under three times of the standard driving cycle. Comparing the results, the error was less than 6% of all exhaust emissions. It reflected OBS-584 is of good precision and stability, shown on Figure 3 and Table 2. Figure 1 Rural arterials(c2-7-2) Figure 2 urban streets(c5-10-2) Figure 3 OBS-584 on-board system Figure 4. View of OBS-584 system installed in a vehicle Table 2 Comparing the instrumentation CO (g) HC (g) NO (g) CO 2 (g) On-board system: OBS-584 17.09 0.875 0.1628 422.63 Equipment of Laboratory: HORIBA-MEXA 9000 16.115 0.877 0.1660 418.75 Error (%) 6.2 - -1.8 0.9

EXPERIMENTAL RESULTS In this study, two selected scooters which fit the homologation of two periods respectively and are equipped with carburetor of A type scooter and with electronic injection system of B type scooter. Fig. 5 shows the comparison of total mass emissions of two type scooters on rural arterials. It can be found that B type scooter exhausted lower CO and THC emissions than A type scooter s, but NO and CO 2 emissions were opposed. There is not a big difference with fuel economy on rural arterials. Fig. 6 shows the comparison of total mass emissions of each two type scooters on urban streets. It also can be seen the trends of exhaust emissions are similar to rural arterials. C5 10 2 C2 7 2 A type B type A type B type Figure 6. The comparison of total mass emissions of each two type scooters on urban streets Figure 5 The comparison of total mass emissions of two type scooters on rural arterials Comparing with exhaust emissions on this two type scooters, on rural arterials, CO and THC emission of A type scooter are more than 7 times and 16 times as many as of B type scooter s, respectively; however, CO 2 and NO emission of A type scooter is less than 0.79 times and 0.56 times of B type scooter s respectively; on urban streets, CO and THC emission of A type scooter is more than 8 times and 15 times as many as of B type scooter s, respectively; nevertheless, CO 2 and NO emission of A type scooter is less than 0.77 times and 0.65 times of B type scooter s respectively. From the results that mentioned above, the

advanced electronic inject system that is equipped with B type scooter could effectively control CO and THC emissions, but NO is generated according to the engine combustion temperature, the higher temperature in combustion, NO is generated more. Fig. 7 and Fig. 8 show the comparing with exhaust emission of two type scooters on two different roads. It is obviously that most exhaust emissions of two scooters on urban streets are higher than rural arterials, especially CO and THC emissions. B type C2 7 2 C5 10 2 A type C2 7 2 C5 10 2 Figure 8. The comparison of total mass emissions of B type scooters on rural arterials and urban streets Figure 7. The comparison of total mass emissions of A type scooters on rural arterials and urban streets Comparing with exhaust emissions of A type scooter on this two different level road, CO, THC, NO and CO 2, emission on urban streets are more than 2.2, 2.9, 1.1 and 1.5, times than on rural arterials, respectively; CO, THC and CO 2 emissions of B type scooter on urban streets are more than, 1.4, 3.1and 1.6 times respectively, but NO emission is nearly even on rural arterials. Fig. 9 shows the comparing with speed distribution of two types of scooters on two different roads. This results show that different level roads, such as:traffic flows and signal plans, road level, and loads etc. greatly affect exhaust emission of scooters.

The trends of exhaust emissions of B type scooter are as same as A type scooter, but the maximum intensity of CO emission was occurred at maximum deceleration of vehicle. The exhaust emissions of B type scooter in each speed and acceleration range under urban streets exhaust emissions are increased with velocity and acceleration increased, but CO maximum intensity of B type scooter under urban streets is occurred at maximum deceleration and velocity. Figure 9. Comparing with speed distribution of two type scooters on two different roads Fig. 10 and Fig. 11 are the matrix of exhaust emissions for each velocity and acceleration on urban streets of two scooters. For the A type scooter, the maximum intensity of CO, NO and CO 2, were occurred at maximum speed and acceleration range which are 46 to 50 kph and 4 to 10 kph/s. The maximum intensity of THC falls within the area of maximum accelerations and speed range 31~36 kph. Figure 11. The exhaust emissions of B type scooter in each speed and acceleration range under urban streets Table 3 Emission standard of Scooter in Taiwan Standard CO HC NOx HC+NOx (g/km) (g/km) (g/km) (g/km) Phase 4 7 - - 2 Phase 5 2 0.8 0.15 - Table 4 Test results on real word in Taiwan Scooters Road level CO THC NO (g/km) (g/km) (g/km) A type Urban street 17.19 3.23 0.4 (Phase 4) Arterial street 7.86 1.13 0.36 B type Urban street 2.7 0.22 0.62 (Phase 5) Arterial street 1.98 0.07 0.64 Figure 10. The exhaust emissions of A type scooter in each speed and acceleration range under urban streets The emission standard of scooter and the test results on real word in Taiwan are shown on table 3 and table 4. Comparing with CO emission, A type scooter driven on urban and arterial street is more 2.46 and 1.12 times than

emission standard of scooter in Taiwan respectively; moreover, B type scooter driven on urban and arterial street is more 1.35 and less 0.99 times than standard respectively. On the other hand, although THC (HC and CH 4 ) and NO are acquired in this paper, the emission standard of scooter in Taiwan is HC and NO x, it can not be comparison between the test results and standard in this paper. CONCLUSIONS This study used two types of scooters installed with the OBS-584 (developed by ARTC) to measure exhaust emissions from driving on different roads of the real world. 1. The result shows the scooter which is equipped with advanced electronic fuel injection system (B type) could well control CO and THC emissions which reduce nearly 84% and 93% respectively, but NO reversely increased 55%. 2. The result shows the scooter which is equipped the advanced electronic fuel injection system (A type) could perform better fuel economy which increased nearly 9% on urban streets. 3. The exhaust emissions are also affected by road level, all exhaust emissions on urban streets are significantly higher than on rural arterials. 4. The result also shows that exhaust emissions increased with velocity and acceleration increased, but CO maximum intensity of B type scooter under urban streets is occurred at maximum deceleration and velocity due to the engine characteristic that inadequate air intake causes incomplete combustion which results in CO instead of CO 2 when high speed engine suffers abruptly deceleration. 5. Comparing the test results and emission standard of scooter in Taiwan, it shows the advance engine control module have better exhaust emission control of CO emission. of Mass Emission of NOx, Fuel Consumption, Road Load and Engine Output for Diesel Vehicles, SAE paper 2000-01-1141, 2000 7. K. Nobutaka, and T. Tokihiro, Real-time On-board Measurement of Mass Emission of NOx, Society of Automotive Engineers of Japan volume 23-00, pp13-16, 2000 8. F. Zhao, Technologies for Near-Zero-Emission Gasoline-Powered Vehicle, SAE International, Warrendale 2007. 9. Y. Gao and M.D. Checkel, Emission Factors Analysis for Multiple Vehicles Using an On-Board, In-Use Emissions Measurement System, SAE Technical Paper series 2007-01-1327, 2007. ACKNOWLEDGMENTS This work is supported by Research of vehicle dynamic energy consumption and greenhouse gas emissions characteristic - the example within less than 150 c.c. motorcycle MOTC-IOT-101-PDB001 of the Institute of Transportation MOTC, Taiwan, R.O.C. REFERENCES 1. H. C. Frey, A. Unal, N. M. Rouphail, and J. D. Colyar, On-Road Measurement of Vehicle Tailpipe Emissions Using a Portable Instrument, Journal of the Air & Waste Management Association, Technical Paper, volume 53, pp992-1002, 2003 2. P. D. Haan and M. Keller, Emission factors for passenger cars: application of instantaneous emission modeling, Atmospheric Environment volume 34, issue 27, pp4629-4638, 2000. 3. M. Jerzy, P. Jacek, and P. Ireneusz, Road Test Emissions Using On-board Measuring Method for Light Duty Diesel Vehicles, Jordan Journal of Mechanical and Industrial Engineering, volume 5, issue 1, pp89-96, 2011. 4. J. Jetter, S. Maeshiro, S. Hatcho, and R. Klebba, Development of an On-board Analyzer for Use on Advanced Low Emission Vehicles, SAE TECHNICAL PAPER 2000-01-1140 5. S. Cernushi, M. Giugliano, A. Cemin, and I. Giovannini, Modal Analysis of Vehicle Emission Factors, Sicence of the Total Environment volume169, issues1-3, pp175-183, 1995 6. N. Kihara, T. Tsukamoto, K. Matsumoto, K. Ishida, M. Kon and T. Murase, Real-time On-board Measurement