This year’s low-emission technology forecast for commercial vehicle diesel generator sets

In the fuel injection system that improves the combustion effect significantly, 'high-pressure injection' and 'injection freedom' have become important means in the current fuel injection system.The common rail injection system has entered the second generation, and can achieve an injection pressure of 160-180MPa and five multi-stage injections within the variable range of the injection period above 180°C.In the future, through measures such as improving the strength of each part of the common rail injection system and reducing oil leakage, it is expected to achieve high-pressure injection above 200MPa.
In the future, there are methods to improve combustion such as premixed combustion and low NOx combustion. In order to achieve premixed combustion, measures such as multi-stage injection and switching combustion methods that can promote premixing are adopted, which requires a higher degree of injection freedom.In addition, due to high EGR and low NOx combustion, it is necessary to consider further increasing the injection pressure as a black smoke countermeasure when the O2 concentration in the intake air is greatly reduced.On the other hand, the combination of the fuel injection system and after-treatment technology is also important. The NOx adsorption and reduction catalytic converter requires a different post-injection mode from the DPF.While strengthening injection freedom and high-pressure injection, it is expected that concepts such as 'change in combustion method' and 'combination with post-processing' will be added to new keywords.To control the compression ignition combustion of a uniform premixed gas, it is necessary to control very difficult physical quantities such as the pre-ignition temperature history and the gas composition and heat capacity in the cylinder that affect the chemical reaction that governs fuel oxidation. It is expected that the computing power of the sensor and control unit will be greatly reduced. Realize practicality.The 'premixed combustion' proposed by Kamimoto et al. avoids combustion in the NOx and carbon smoke generation areas on the flame temperature and equivalence ratio (T-Φ) diagram, achieving ultra-low emissions.
In addition, the improvement of thermal efficiency is also an important factor.The 'Clean Diesel Combustion' concept proposed by the (EPA) and the 'ACTION' concept proposed by the British Ricardo Research Institute are to reduce the O2 concentration in the cylinder to 11%-14%, achieving a reduction without reducing combustion efficiency. NOx emissions are 90%.In order to realize this concept, to take into account both supercharging and high EGR without increasing fuel consumption, it is necessary to rely on technologies such as low compression ratio, two-stage supercharging, electric compressor and low-pressure circuit (LPL) EGR. The basics are EGR+ air volume control and promotes the mixing of fuel and air to suppress soot generation.On the other hand, premixed diesel engine combustion is a combustion method that aims at not overlapping the fuel injection period and the combustion period and not causing diffusion combustion (i.e., non-homogeneous).Injecting fuel earlier before top dead center or injecting fuel during the expansion stroke to fully ensure ignition delay has great potential for reducing emissions.