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Development of Heavy Duty Vehicles CO2 certification for Heavy Buses and Medium Lorries

Abstract: 

In 2019, a Verification Test Procedure (VTP) – to be applied randomly on complete vehicles after the certification processes – became a part of the HDV CO2 Certification Regulation (EU/2019/318). The VTP consists of an on-road test to verify the CO2 emissions of new vehicles after production. At the same time, a new regulatory initiative aiming at the certification of the FC from HDVs not covered in EU/2017/2400 was initiated. The new methodology will also include a VTP test; however, adapted for vehicle categories such as Heavy Buses and Medium Lorries. In this framework, DG-GROW requested JRC to launch a test campaign to investigate the validity, accuracy, and feasibility of the proposed methodology for these vehicle categories. Experiments were conducted on four Euro VI HDVs; two Heavy Buses and two Medium Lorries. All on-road tests proved to be highly repeatable with the SE for the WSFC not exceeding 2%. Both Coaches showed a quite good agreement between the measured and simulated WSFC with the deviation not exceeding 5.5%. Medium Lorries exhibited a different behaviour mainly due to the overestimation of the electrical power demand of auxiliaries by VECTO in the VTP Mode. Overall, a less transient route, similar to the regulated, seems more appropriate for the VTP of Coaches. On the other hand, a more transient route might be more suitable for the VTP of Medium Lorries. Increasing the payload from 60% to 80% does not seem to affect the test repeatability. The CVTP for both vehicles fulfilled the pass criterion defined in 2019/318 for Heavy Lorries in all 14 tests. The FC data were analyzed to understand the suitability of different instruments to provide accurate FC measurements. The FC calculated from the PEMS CO2 emissions is generally close to the reference FFM FC with the averaged deviation not exceeding 4% in the vast majority of the tests. The ECU FC seems to be slightly less accurate compared to the PEMS FC. Both PEMS and ECU seem to perform equally well both under non-transient and highly transient conditions. Finally, one of the goals of the study was to collect experimental data of pollutant emissions during the VTP test. NOx emissions were generally low and did not exceed the EURO VI engine certification limit (0.46 g/kWh). The more transient routes exhibited higher NOx emissions pointing to a less effective operation of the catalyst under these conditions. CO emissions were generally low and well below the EURO VI engine certification limit (4.0 g/kWh).