At present, the emission reduction policy of mobile sources has been promoted rapidly, and the environmental protection management documents of mobile sources have formed a system, including 1 general document, 3 key projects and 3 special projects. The research plan of mobile source in autumn and winter is carried out at the same time. The regulatory authorities have made great efforts in strictly implementing the adjustment of transportation structure, speeding up the elimination of old vehicles (national III and IV), severely investigating and punishing excessive emissions of motor vehicles, strengthening the supervision and management of oil products, and building an integrated monitoring system for motor vehicles (online monitoring system). For the future development trend of emission standards, there will be "National Seven" after "National Six", and the supervision of emissions will only become stricter and stricter. At present, the potential of emission control technology has been able to support ultra-low and near-zero emission control requirements, but the development of emission control technology will also bring new challenges, such as NO (nitrogen oxides), NH (ammonia) emissions and mixed emissions. It is worth noting that the coordinated emission reduction of greenhouse gases is a problem to be considered in the future mobile source standards of China.
Among them, in the study of engine oil management, the particulate matter emitted by the engine is composed of soot and semi-active substances adsorbed on the surface or gap. Semi-active substances generally include organic hydrocarbons and sulfur-containing inorganic components. Hydrocarbon components include hundreds of highly toxic and carcinogenic complex organic compounds, such as polycyclic aromatic hydrocarbons. Therefore, the volatility of particulate matter emitted by engine is one of the important criteria to evaluate the harm degree of particulate matter.
Organic carbon (organic? Carbon? OC) and elemental carbon (elemental? Carbon? EC) is the main component of engine exhaust particles, and the semi-volatile components in OC overlap greatly. EC is one of the important factors that affect atmospheric visibility. Occasionally, the formation mechanism of exhaust particles in different particle size ranges is different, resulting in different particle sizes and their components. Therefore, it is necessary to study the volatility and composition of exhaust particulate matter under different engine conditions on the basis of distinguishing the particle size.
Suride technology focuses on the research and development of industrial application-grade OBD CAN bus data and emission products, and is constantly exploring industrial applications and needs. It adopts automobile-class, distributed and modular underlying architecture design. 20 19 adopts intelligent automatic adaptation and 5G technology for the first time, and there is no need to crack the agreement to adapt to different brands of vehicles, thus ensuring the rapid and efficient completion of project testing and implementation. In 20 16, the local standard DB1-1475 was established with China Automobile Research Institute, Tsinghua University, Ministry of Environmental Protection and Bureau of Metrology in the monitoring technology of vehicle exhaust emission exceeding the standard. 20 16 laid out the on-line monitoring technology of automobile exhaust emission exceeding the standard, responding to the national call for industry customers and winning the national "blue sky defense war". In order to study oil products, we choose a four-cylinder, naturally aspirated and direct injection diesel engine. The engine is connected with a dynamometer, and the rotating speed and torque of the engine are adjusted through the dynamometer system. In order to ensure the repeatability and comparability of the test, the cooling water of the engine is automatically controlled at 80 degrees Celsius with an error of 2 degrees, while the oil temperature is controlled at 90- 100 degrees.
Three different fuels, ultra-low sulfur diesel (ULSD), biodiesel (BD) and low sulfur diesel (LSD), were selected to study the particulate emission characteristics of compression ignition engines. The sulfur content of ultra-low sulfur diesel oil is lower than 10PPM. Biodiesel comes from restaurant waste oil and is purchased from DP company. Its physical and chemical properties meet the European biodiesel standard EN 142 14, and the sulfur content of low sulfur diesel is about 400PPM.
The test data are as follows:
Note: 20 degrees means measuring at 20 degrees, 40 degrees means measuring at 40 degrees,%? Wt stands for mass percentage.
Particulate matter produced by biodiesel and ultra-low sulfur diesel combustion first decreases and then increases with the increase of coincidence degree, while the volatility of low sulfur diesel particles increases monotonically with the increase of coincidence degree. Under low load condition, due to the low combustion temperature in the cylinder, there are a lot of unburned hydrocarbons or lubricating oil components in the engine exhaust, which can be converted into a lot of volatile particles in the process of tail gas dilution and condensation, which can explain the relatively high volatility of biodiesel and ultra-low sulfur diesel particles under low load condition.
Under high load conditions, unburned hydrocarbons and lubricating oil components have little contribution to the volatility of particulate matter due to the high combustion temperature in the cylinder, while high combustion temperature promotes the transformation process of sulfur components in fuel to sulfuric acid or sulfate, so sulfuric acid or sulfate is an important component of volatile particulate matter under high load conditions. Because of the relatively high sulfur content, the formation mechanism of this volatile particulate matter is more obvious when burning diesel with relatively high sulfur content.
Conclusion:
1, burning biodiesel can effectively reduce the quantity and quality of particulate matter emissions. Compared with low sulfur diesel, the inhibition of biodiesel on particulate matter is reflected in the whole particle size range, while for ultra-low sulfur diesel, it is mainly reflected in large particle size.
2. Qualitative and quantitative measurement based on the volatility of particulate matter shows that burning biodiesel can effectively reduce the emission of volatile particulate matter in the whole particle size range compared with ultra-low sulfur diesel, while biodiesel can lead to higher emission ratio of volatile matter, mainly concentrated in the small particle size range.
3. For the particulate emissions produced by three different fuels, the mass ratio of volatile substances first decreases and then increases with the increase of particle size, while the quantity ratio monotonously decreases with the increase of migration particle size.
4. Burning biodiesel can obviously reduce the content of polycyclic aromatic hydrocarbons in particulate matter, especially for the high molecular weight polycyclic aromatic hydrocarbons produced by combustion (professional experiments, only results can be obtained).
5. The toxicity analysis based on BaPeq shows that the small particle size shows strong equivalent toxicity, and burning biodiesel can obviously reduce the equivalent toxicity and equivalent toxicity concentration of particles.
With the continuous improvement of detection technology, people's research on vehicle particulate emissions has developed from smoke measurement and mass weighing to detailed analysis of quantity concentration, particle size distribution and various related physical and chemical characteristics, including particle morphology, internal microstructure, oxidation activity, various detailed chemical components and volatility. Through the analysis of various physical and chemical characteristics of particulate matter, it is helpful to better study the formation mechanism of particulate matter, its harm to people and its elimination methods, and provide reference for the formulation of relevant policies and regulations in the sixth and seventh countries in the future. To this end, the National Bureau of Ecology and Environment issued a document, and from 2020, it will implement the national six B emission standards for new light gasoline vehicles and heavy diesel vehicles in other industries.
By the end of 20 17, the number of automobiles in China was 2170,000, and the number of diesel vehicles169.09 million, accounting for only 7.8%. However, the nitrogen oxides emitted by diesel vehicles accounted for 57.3% of the total vehicle emissions, and the particulate matter emitted accounted for 77.8% of the overall level, which was the main contributor to vehicle pollution emissions.
By the end of 20 18, the total number of diesel trucks in China was18/0/80,000, accounting for 7.9% of the total number of vehicles, but nitrogen oxide emissions accounted for 57.3% of the total and particulate matter accounted for 78%. Unreasonable transportation structure, high density of diesel trucks and oil quality problems are the main reasons for this phenomenon.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.