NH3 sliding limits were applied under China V when the NH3 sliding limit was 25 ppm (peak) and 10 ppm (cycle mean). For China VI, the NH3 sliding limit is 10 ppm (cycle average). In addition to more realistic test cycles and strict emission limits, China`s VI standard also introduces additional requirements for off-cycle testing, including the World Harmonized Not-to-Exceed (WNTE) test and a comprehensive PEMS test for vehicles. The test requirements and emission limits of the WNTE test in China VI are euro VI compliant. requirements for the position and orientation of the exhaust outlet to facilitate the testing of vehicle emissions, the observation of a remote sensing device and the conduct of a PEMS test. The State Council of the People`s Republic of China (State Council Document No. 22, 2018) (7) on March 3,22, 2018) The «Three-Year Action Plan for Victory in the Blue Sky Defense War» issued in July 2018 urges the early implementation (by July 1, 2019) of the China VI standard for heavy vehicles in key areas (including the Beijing-Tianjin-Hebei region and surrounding areas) to prematurely implement China`s Standard VI for heavy vehicles (including the Beijing-Tianjin-Hebei region and surrounding areas) (by July 1, 2019). Yangtze River Delta, Fenhe and Consecration Plains), Pearl River Delta and Chengdu-Chongqing Region. Higher requirements and tighter timelines pose challenges for the implementation of the standard. The publication and implementation of China VI emission standards for heavy-duty diesel vehicles is one of the important steps to comply with China`s Blue Sky defense action plan.
This paper analyses the basis of the technical requirements and their effects by interpreting the context and main technical content of China`s Vi emission standards. In addition, the main differences between the China VI and China V emission standards and the Euro VI regulations are highlighted, hoping to give the relevant industry an in-depth overview of the new standard. Unlike previous standard phases, which closely comply with European emission standards, China 6 combines the best practices of European and American regulatory requirements and creates its own. In particular, the standard features: China VI standards include two phases, China VI-a and China VI-b. China VI-a is largely euro VI compliant. China VI-b introduces stricter testing requirements (including a PR limit of 1.2×1012 kWh-1 for PEMS testing for the entire vehicle) and a remote monitoring system. China VI is implemented in two stages: VI-a and VI-b according to the rigor of technical requirements. The standard applies to diesel-powered vehicles and gasoline-powered vehicles. As shown in Table I, the effective date of this standard varies due to the different levels of preparedness of the two industries for different types of vehicles and different levels. With regard to the environmental conditions of the PEMS test, the China VI standard, based on its own national situation, introduces different height requirements than those of EU legislation. Since one third of the country`s territorial area is greater than 2000 m, China VI increases the altitude range of the PEMS test to 2400 m (from phase VI-b to be performed) to meet the requirements of controlling motor vehicle emissions in high-altitude areas and to cover provincial capitals such as Kunming City and Xining City. The China VI standard proposes stricter emission limits and adds relevant technical requirements, drawing on international experience and taking into account China`s specific administrative needs.
In addition, this standard incorporates the many changes made to the Chinese environmental management system for mobile sources, which, together with the main technical contents of this standard, are analyzed in detail in the following sections. China VI`s regulations include OBD requirements based on the Euro VI OBD program. An OBD system must be installed in all China VI engines and vehicles to identify, record and communicate the types of malfunctions. The OBD limits are listed in Table 7. If emissions exceed an OBD threshold over a period of time, a permanent code must be stored on the computer. An operator incentive system is also required which, when activated, reduces the vehicle`s torque and/or limits the maximum speed . The China VI regulation includes a multi-component compliance program that includes emissions tests carried out by authorities and manufacturers during the pre-production, production and use phases. It also includes comprehensive PEMS testing requirements for vehicles based on European PEMS regulations. According to the China VI standard, emission tests for road vehicles include gaseous pollutants (NOx, CO) and PR as well as CO2 emissions. The PEMS test in European and US regulations also sets the measurement and limits for total hydrocarbons (THC). However, since THC emissions from heavy-duty diesel vehicles are generally very low and the compressed hydrogen required for flame ionization detector (FID) as recommended in the regulations presents a potential risk, associated with the high cost of meters and operating requirements, the PEMS test specified in China VI does not make the thc test mandatory for diesel-powered vehicles.
To date, the Euro VI Regulation does not explicitly set an EBSM emission limit value for particulate matter. Given the level of air pollution in China, the Chinese government considers it necessary to add relevant requirements for particulate matter in China VI. Since the accuracy of the PEMS-PN test is better than that of the PEMS-PM test, China VI provides for the PEMS-PN test and its emission limits.