1. If the increase in fuel quality improvement of cetane number of diesel, can effectively reduce the diesel generator exhaust particles PM, CO and NOx emissions; reduce the amount of fuel in the S can be reduced 13 to 22% of the PM particulate emissions; reducing fuel aromatic ingredients that can reduce NOx emission “style =” float: right; clear: both; top: 0; vertical-align: top; “>
1. Improve fuel quality
If the increase in the cetane number of diesel, can effectively reduce diesel exhaust particles PM, CO and NOx emissions; reduce the amount of fuel in the S can be reduced 13 to 22% of the PM particulate emissions; reduce fuel aromatic ingredients that can reduce NOx emissions.
Measures to improve fuel as follows:
① According to the fuel distillation range, reasonable increase fuel cetane number.
② in diesel blended with a certain proportion of smoke additive metal barium, magnesium, zinc and other soluble alkaline or neutral salts as smoke additive, through the promotion of combustion of soot particles and then during the expansion process, and to promote the elimination of injector head soot can be reduced 30 to 50 percent of soot particles PM emissions.
③ reduce fuel sulfur content. In the combustion process, sulfur in diesel, about 98% is converted to SO2, the remaining 2% sulfate particles become, part of SO2 is further oxidized in conjunction with the combustion process to generate H2O, H2SO4, and the formation of sulfate (CaSO4, etc.), increased emissions of particles.
2. After the exhaust purification processing
Ternary oxide catalytic converter for diesel exhaust gas treatment can reduce emissions of HC and CO and particulate matter PM in the organic components; catalytic converter reduces NOx reduction in excess oxygen selective, with a particulate filter device collected diesel exhaust particulate substances.
① use of the particulate filter and regeneration of the particulate filter technology and by the particulate filter regeneration device component. Particulate filter which has a very small pore through the filter media (filter) trap diesel exhaust fixed carbon particles and adsorption of soluble organic components soot.
② install diesel oxidation-type catalytic converter installed oxidized catalytic converter is an efficient machine outside purifying exhaust gas and combustible gases commonly used measures SOF soluble organic components. Adding oxidized catalytic converter (platinum Pt, Pd precious metal palladium as a catalyst) to make HC, CO 50% reduction in particulate PM reduced by 50 to 70 percent, PAHs and nitro-PAHs are also significantly reduced .
At present the main research direction of ③ non-filter technology, there are two non-filter technology: electrostatic particle collector. Diesel Exhaust Particulates 70 to 80% were charged state, each with charged particles from about 1 to 5 basic positive charge or negative charge, as a whole is electrically neutral. Currently attached to the use of a strong electric field on the properties was charged soot particles electrostatic adsorption, and made certain test results, but because of the additional equipment bulky, complex structure and high-voltage supply source, etc., to bring some practical difficulties.
④NOx catalytic converter NOx catalytic converter for NOx in the temperature range 350 ~ 550 ℃ were good catalytic converter, the NOx emissions reduced by 20 to 30%. NOx catalytic converter technology can be divided into catalytic thermal decomposition and selective catalytic reduction two kinds. Catalytic thermal decomposition is the use of a metal ion zeolite, vanadium and molybdenum catalyst to reduce NOx thermal decomposition reaction activation energy, the NOx is decomposed into non-toxic N2, the reaction product of the method is simple and non-toxic; selective reduction is in the exhaust gas injected into the saturated HC and NOx, the reaction product was N2, CO2 and H2O, selective reduction reaction will generate additional CO2. (Editor: China full power) 3. Conducted within the diesel engine in the purification of diesel engine combustion process of purification is optimized so that the diesel engine to reach mixing, combustion, pastel work, reliable starting and reduce emissions. ① prevent the string into the oil burning “style =” float: right; clear: both; top: 0; vertical-align: top; “>
3. Purifying machine for Diesel Engine
Purification is to optimize the combustion process in the diesel engine, diesel engine to reach mixing, combustion, pastel work, reliable starting and reduce emissions.
① prevent the oil stream into the combustion chamber due to the considerable part of diesel exhaust particulate matter is composed of a string of oil into the combustion chamber of incomplete combustion, it should be possible to reduce the amount of oil string.
② the use of electronically controlled high pressure diesel injection technology and diesel electronic control technology from the position control of the first generation, the second generation of the time control to today’s Common Rail high-pressure injection. Electronically controlled high pressure injection control of the fuel injection control law, according to the diesel engine operating conditions to achieve the best fuel injection, and combustion by controlling the ratio of premixed combustion and diffusion, which can reduce harmful diesel emissions and air-fuel ratio control, help outside the machine to achieve effective purification measures.
③ improve the fuel injection pressure and nozzle diameter is reduced to improve the fuel injection pressure and reduce the nozzle diameter particles can significantly reduce PM emissions. In order to avoid high-pressure injection increases NOx caused, due to lower requirements for air swirling motion, improve the compression ratio and a variable fuel injection timing of its adapting to achieve the purpose of controlling the particle PM and NOx emissions.
④ improve the combustion system to improve combustion system refers to the shape of the combustion chamber, fuel system, intake best match flow. In the diesel engine should ensure that the entire range of operating conditions, uniform distribution of fuel in the combustion chamber, a suitable gas flow, there are reasonable rules and injection timing of fuel injection. Using electric fuel pump control, electronically controlled pump – nozzle, electronic speed regulator, variable swirl system, multi-valve fuel injectors and central configuration and other measures, can improve engine performance, but also reduce diesel exhaust emissions, especially PM particulate matter emissions.
⑤ using exhaust gas recirculation (EGR) EGR exhaust gas is introduced into the part of the intake system, by reducing the maximum temperature of the combustion chamber to reduce NOx emissions. The use of EGR to reduce NOx emissions, electronic control combined with the need, according to the engine load, speed, cooling water temperature sensor and starter switch signal from the ECU rate of EGR and EGR random controls to ensure that in the performance of the diesel engine has little impact conditions , reducing NOx emissions.
⑥ Turbocharged Turbocharged technology increases the average temperature in the cylinder mean effective pressure, and excess air ratio over the cycle, can reduce the emissions of diesel particulate matter by 50% and reduce CO and CH emissions. The use of cooling technology, NOx emissions can be reduced by 60 to 70%. So the use of a turbocharged and intercooled is one of effective measures to reduce vehicle emissions of diesel exhaust. (Editor: China full power) 4. Use of alternative fuels using alternative fuels will be an important method for controlling diesel and gasoline engine emissions. Currently alternative fuels are mainly natural gas (compressed natural gas CNG, liquefied natural gas LNG), liquefied petroleum “style =” float: right; clear: both; top: 0; vertical-align: top; “>
4. Use of alternative fuels
Use of alternative fuels will be an important method for controlling diesel and gasoline engine emissions. Currently alternative fuels are mainly natural gas (compressed natural gas CNG, liquefied natural gas LNG), liquefied petroleum gas (LPG), methanol, ethanol, hydrogen fuel and diesel fuel blended compound, wherein methanol, natural gas, liquefied petroleum gas is considered to be the most promising clean energy alternative fuels. Alternative fuels features:
① low natural gas car costs, abundant reserves, mainly compressed natural gas vehicles CNG represented. CNG gaseous fuel itself, without atomization, combustion, low CO content in the exhaust, no smoke, but the power reduced by 10%, to bring inconvenience.
② methanol having a high octane, low-calorie, low-pollution and smoke-free features. But methanol is low cetane number, ignition poor, need to install an ignition device, poor cold start, corrosive, and to resolve Japanese oil consumption process to reduce emissions of unburned methanol.
5. The diesel exhaust purification device
With increasing car ownership, car exhaust on human health hazards and environmental pollution is also increasing intensity. In this regard, countries in the world to develop the appropriate regulations and standards, in order to control harmful emissions cars at a lower level. In order to meet emission standards for diesel engine exhaust gas must be purified. In recent years, the automobile industry to develop and create many new technologies and means of purifying the exhaust gas.
Harmful emissions (1) diesel engine
Piston internal combustion engine powered cars is one of the main sources of urban air. The main pollutants in vehicle emissions of carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx) and particulates. CO is a product of incomplete combustion of fuel, is a colorless, odorless, tasteless gas. It affinity with the hemoglobin in the blood is 300 times that of oxygen, so when people inhale CO, absorption and transport of oxygen in the blood can be reduced, resulting in dizziness, headache and other symptoms of poisoning. When inhaled volume containing a concentration of 0.3% CO gas, can cause people to death. NOx mainly refers to NO and NO2, produced in the combustion chamber high temperature oxygen-rich environment. NOx concentration in the air at 10 ~ 20ppm can stimulate the oral and nasal mucosa, cornea and so on. When NOx exceeds 500ppm, a few minutes can make the person died of emphysema. (Editor: China full power) (2) secondary air injection system (Figure 1) Figure 1 – secondary air injection system is equipped with a lot of automotive diesel secondary air injection system. While the secondary air injection system have a variety of structures, but its function is basically the same “style =” float: right; clear: both; top: 0; vertical-align: top; “>
(2) secondary air injection system (FIG. 1)
Secondary air injection system of Figure 1 –
Many diesel cars equipped with secondary air injection system. While the secondary air injection system have a variety of structures, but the same basic function, namely the use of an air pump fresh air into the spray nozzle through the air exhaust passage or catalytic converters, exhaust gas CO and HC further oxidation or combustion to carbon dioxide (CO2) and water (H2O). (Editor: China full power) (3) three-way catalytic converter (Figures 2, 3) three-way catalytic converter using a catalyst role in the exhaust gas CO, HC and NOx is converted to harmless gas An exhaust gas purification device, also known as catalytic transfer “style =” float: right; clear: both; top: 0; vertical-align: top; “>
(3) three-way catalytic converter (Fig. 2,3)
Three-way catalytic converter is the use of a catalyst role in the exhaust of CO, HC and NOx is converted to harmless gas in an exhaust gas purification device, also known as catalytic converters. Platinum, palladium or rhodium can be used as a catalyst. In the chemical reaction, the catalyst only a part of the promotion of the reaction, the reactants are not.
Figure 2 Figure 3
Catalytic converter oxidation catalytic converter and the three-way catalytic converter. Only the oxidation catalytic converter in the exhaust gas HC and CO oxidized to CO2 and H2O, so that the catalytic converter is also called two yuan catalytic converter. Secondary air as the oxidant must be supplied to the oxidation catalytic converter, in order to make it work effectively. Three-way catalytic converter which can reduce CO, HC and NOx emissions, it exhaust CO and HC as a reducing agent, the NOx is reduced to nitrogen (N2) and oxygen (O2), and the reduction in CO and HC It is oxidized to CO2 and H2O. When simultaneously using two converters, usually both placed in the same converter housing, and three-way catalytic converter in front of the oxidation catalytic converter. After the exhaust gas through the catalytic converters, some not oxidized CO and HC in the oxidation catalytic converter to continue with the secondary air supplied to the oxidation reaction. (Editor: China full power) (4) diesel particulate filter (Fig. 4) diesel exhaust particles (mainly soot – the main component of soot) is a prominent problem of diesel engine emissions. Vehicle handling of diesel exhaust particulate, the main filtration “style =” float: right; clear: both; top: 0; vertical-align: top; “>
(4) diesel particulate filter (Figure 4)
Diesel exhaust particles (mainly soot – the main component of soot) is a prominent problem of diesel engine emissions. Vehicle exhaust treatment for diesel particulates, mainly filtration.
A particulate filter made of a porous ceramic filter which has high filtration efficiency. Exhaust gas through the porous ceramic filter into the exhaust pipe, and the particles are retained on the filter. After the filter working for some time, the need for timely remove particles accumulated in the filter, the filter to restore the ability to work and reduce exhaust resistance. For this purpose, a burner at the entrance to the filter by injecting a small amount of fuel injector into the burner, and the secondary air supply, the use of a spark plug or glow plug to ignite the particles retained in the filter burn out.