| According to the shortage of the fossil fuel and CO2 emission reduction pressure, the diesel engine are more and more widely used for its advantage. But the emission of the diesel engine which contained NOx, PM and other pollutant also increased quickly. Countries unveil new emission regulations to limit pollutions, especially NOx. The SCR(Selective Catalyst Reduction) technology is a developed technology for diesel engine after-treatment. The urea injector which used as the key part of the SCR system could influence the SCR effect.We built the drop size test system and engine dyno system for the research. And introduced the composition, principle and measuring instrument, including the HELOS-VARIO laser analyzer, engine etc. Experiment research on the flow-rate characteristics, spray angle, distance, SMD and its distribution in space. We found the air-assisted is better than air-less one according to the compare test at the first stage. Therefore, different kinds of air-assisted rotational flow injectors have been developed and test. Based on the test result, an new external mixing injector have been developed to reduce the particle size at the outside of the spray cone. According to the test, we got two superior injectors with 85°~95°and 50°~60° spray angle. And the SMD range is 30~150?m and 25~120?m.Finally, the new design injectors have been verified on the engine dyno system with the urea dosing system... |
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