The exhaust gas emission technical route is usually expressed in uppercase English letters.
What do you mean by English letters? What role does it play in exhaust gas processing?
Before we get to know these English letters, we must first understand that the engine exhaust includes gaseous pollutants and particulate pollutants. Among them, gaseous pollutants are carbon monoxide (CO), nitrogen oxides (NOx, equivalent nitrogen dioxide (NO2), hydrocarbons (HC); particulate pollutants (soot) are mainly carbon, condensed hydrocarbons, sulfuric acid brine Therefore, in order to make the exhaust emission meet the specified limit, it is necessary to install corresponding processing devices, and these devices are usually indicated by abbreviations.
Diesel engine exhaust gas purification principle
DOC (Oxidation Catalytic Converter): To achieve oxidation treatment of carbon monoxide and hydrocarbons.
SCR (Selective Catalytic Reduction System): Considering the corrosivity, toxicity and strong irritancy of ammonia, the reducing agent (urea) is used to selectively reduce nitrogen oxides to nitrogen in an oxygen-rich environment under the action of a catalyst. water.
EGR (Exhaust Gas Recirculation): In order to reduce the nitrogen oxide content in the exhaust gas, the OEM has chosen to inject the exhaust gas into the engine cylinder for combustion, thereby reducing the nitrogen oxide content in the exhaust gas.
Hi-SCR (hydrocarbon catalytic converter): mainly used in combination with SCR (selective catalytic reduction system) and DOC (oxidation catalyst) to reduce the nitrogen oxide content in the exhaust gas.
DPF (Particle Trapper): The unoxidized particles (soot particles) in the exhaust gas are trapped in the trap, and the high-temperature combustion emits carbon dioxide which is harmless to the human body.
ASC (Ammonia Oxidation Catalyst): The conversion of reducing agent (urea) to ammonia, both DOC and ASC can significantly improve the conversion efficiency of SCR.
Guoliu emissions require strict 3- to 5-fold nitrogen oxide content in the exhaust gas
The reason why the national six emissions are called the most stringent emissions in history, is mainly reflected in the exhaust gas NOx emission limit is 3-5 times stricter than the national five. After understanding the incomprehensible English abbreviations and their effects, it can be found that both EGR and Hi-SCR have the effect of reducing the nitrogen oxides content in the exhaust emissions. Therefore, the exhaust gas treatment technology of the national six engines on the market has also appeared different.
What are the mainstream technical routes of the country? What are their respective advantages?
At present, domestic mainframe factories have two main routes to achieve the national six emission standards, and there are two routes of EGR and no EGR.
National Sixth Emissions Mainstream Technical Route
The EGR technology route, the technical route represented by EGR+SCR+DOC+DPF is the most common. Because this technical route is the inheritance of the national four and five national technologies, it is a safer solution to use EGR in the era of entering the sixth year. . There are many domestic OEMs adopting this emission route. For example, Xichai 's Aowei series, Jinwei series and Dachai's full-platform models adopt this technical route.
Xichai Aowei 13-liter national six engine
The same is because this technology is relatively mature and easy to maintain, so there are few "weird" faults in the process of use. Compared to the technical route without EGR, the advantages of the technical route with EGR are:
1. The post-processing system is more stable;
2. The amount of urea used in daily use is significantly reduced;
3. The working noise is reduced and there is a good customer experience in use.
Domestic mainstream engine enterprise technology route
Non-EGR mainly uses DOC+DPF+Hi-SCR technology. The domestic main engine factory adopts this technical route. For example, the most familiar with the high-powered and fuel-efficient Weichai WP13 engine .
Weichai WP3 engine
Compared to the technical route with EGR, the non-EGR technology route reduces parts related to EGR, such as EGR coolers. Without the EGR cooler, the engine load is reduced and the power performance is naturally improved. The most obvious advantages of non-EGR routes are:
1. The power performance has been greatly improved;
2. Fuel economy has improved;
In addition, it must be said that the non-EGR technology route treats all pollutants to the aftertreatment system to reach the emission limit, so the performance requirements of the in-cylinder combustion technology and the aftertreatment system are high.
Having said that, I must have a new understanding of the national six emission technology route. In general, both the EGR technology route and the non-EGR technology route have obvious technical advantages. For example, the EGR route is stable and the technology is mature and stable; the non-EGR route is outstanding in power and economy.
I believe that many card friends have already used the National Six engine. Their performance advantages are consistent with the theory. They have their own conclusions through personal experience. It coincides with the upgrade of the National Sixth. It may wish to leave your own opinion and let more friends. When you choose a car, you can buy your favorite product.
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