| On-Road Measurements, Test Bench Measurements and Emission Simulations for a Tractor-Semitrailer in Trans-Alpine Operation |
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| Empa is involved in the German-Swiss-Austrian cooperation for the “Handbook Emission Factors for Road Transport” (HBEFA) and the European COST346 and ARTEMIS projects. All projects aim for accurate emission factors for different transport modes. For heavy duty road traffic, the engine emissions and fuel consumptions are measured on engine test benches in several laboratories across Europe. The emissions are then simulated for different engine- and vehicle classes (truck-trailer, tractor-semitailer, bus, etc.), for different payloads, for different driving cycles (congested urban, congested motorway, free flow motorway, etc.) and for different road gradients using the PHEM simulation tool from the Graz University of Technolgy . For the HBEFA , 31 driving cycles, 7 road gradients, 30 vehicle classes and 5 legislative emission levels (pre-Euro, Euro-1, Euro-2, Euro-3, Euro-4) are simulated which results in more than 30.000 emission factors per emission species (CO, THC, NOx, etc.). For the ARTEMIS project, even more situations will be covered. |
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| Tractor-semitrailer Volvo FH12, equipped with a 309 kW (420 HP) Euro-3 engine |
| | The project described here was the extension of a test bench engine measurement campaign for the emission factors programs: Before the standard program was driven, the Euro-3 D12D420 engine of a Volvo FH12 tractor was measured in the vehicle on the road using the Sensors Inc. Semtech-D portable emission measurement equipment. A tarp-semitrailer was used and the vehicle was loaded to its maximum allowed mass of 40 tons. |
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| Gotthard route |
| | The tractor-semitrailer was driven several times across Switzerland using two of the main Swiss Alp transit routes connecting Germany and Italy. All test runs started in Dübendorf (430 m above sea level) and headed, using the Gotthard tunnel (approx. 1140 m a.s.l.) |
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| San Berhardino Route |
| | or the San Bernardino tunnel (approx. 1620 m.a.s.l.), southwards to Bellinzona (250 m.a.s.l.). The way northwards back to Dübendorf was always driven on the same day so that a typical test run consisted of a 400-500 km long trip crossing twice the Alps. |
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| Vehicle instrumentation |
| | Apart from the concentration measurements of CO2, CO, THC, NO and NO2, several other values such as vehicle speed, engine speed, engine torque and the actual gear were recorded. Additionally, numerous pressures and temperatures as well as the vehicle’s GPS position were measured. This set of data allowed the determination of distance specific data (e.g. g/km) as well as engine work specific data (e.g. g/kWh). The on-road measurements gave reliable and interesting emission data. In trans-alpine operation, the truck with a total mass of 40 tons achieved average speeds around 65 km/h, emitted on the average around 9-10 g/km NOx and consumed on the average around 45-50 l/100 km fuel. |
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| Engine on test bench |
| | After the on-road measurements, the engine was dismantled and mounted on a dynamic engine test bench. The mobile measurement equipment was operated in parallel with the laboratory equipment which allowed the direct comparison of both technologies. |
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| Comparison of mass measurements (mobile equipment relative to test bench equipment) in different cycles |
| | The mobile concentration analyzer (Sensors Inc. Semtech-D) showed a good correlation with the high-precision laboratory system (Horiba Mexa 7400D) for NOx and for CO2. The correlation for THC and especially for CO was weaker. The fuel- and air flow measurement results with the on-road sensors correlated nearly perfectly with the laboratory equipment and the engine speed and torque recorded from the engine control unit (ECU) was normally very close to the test bench data. |
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| NOx emission from on-road and test bench measurement |
| | Even engine emission maps (emission versus engine speed and torque) could be built based on the emission data collected on the road, the accuracy turned out to be good for frequently measured operating points. |
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| Cumulated measured and simulated emissions during a Gotthard test run |
| | In a last step, the emissions from the vehicle test runs were simulated using the emission data measured on the test bench and the driving pattern (speed, road gradient) recorded during the vehicle test runs as inputs for the simulation tool. |
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| Cumulated measured and simulated emissions during a San Bernardino test run |
| | The simulated emissions and the emissions measured on the road match very well so that the basic methodology of the emission factors produced for the several projects mentioned above could be validated. |
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Publications
Soltic, P. and Hausberger, S., Emission Measurements and Modeling of a Tractor-Semitrailer in Trans-Alpine Operation, Proceedings of the 13th International Symposium “Transport and Air Pollution”, September 13-15, 2004, Boulder (CO), USA, pp 157-164 (available through the Atmospheric Chemistry Division, National Center for Atmospheric Research , PO Box 3000 , Boulder, Colorado 80305-3000, USA)
Soltic, P., On-Road Measurements, Test Bench Measurements and Emission Simulations for a Tractor-Semitrailer in Trans-Alpine Operation, Empa Research Report No. 200103, ISSN 1424-2532, PDF available on this website (see link on the upper right side), hardcopies are available for a nominal charge of CHF 50 through karin.lacher@empa.ch
Background Material
U.S. EPA Clean Air Act Enforcement Programme, Diesel Engine Consent Decree: In-Use Test Program
Update of the Emission Functions for Heavy Duty Vehicles in the Handbook Emission Factors for Road Traffic (download zipped Word file)
Comparison Study of Particle Measurements Systems for Future Type Approval Application, EMPA report to the UN-GRPE PMP programme
Sensors, Inc. on-vehicle emission test systems
EU Project on the development of a testing protocol for in-use conformity checking for heaby-duty vehicles (PEMS)
Contact
Dr. Patrik Soltic, Phone +41-(0)58-765 4624, E-mail: patrik.soltic@empa.ch
Acknowledgments
This work was partly financed by the Swiss Agency for the Environment, Forest and Landscape (SAEFL). |
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