Reduction of Nitrogen Oxides by Means of Highly Turbulent Combustion and Modification of Air Composition

通过高湍流燃烧和空气成分改变来减少氮氧化物

基本信息

批准号：
07455096
负责人：
IKEGAMI Makoto
金额：
$ 4.86万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

This study aims at obtaining suggestions for reducing NOx and clarifying the marginal limit of the reduction in the heterogeneous combustion process in practical burners and power systems. The contents of the present study are summarized as follows :1.Production and destruction of NOx in the dilution process of fuel-rich burnt gases are investigated based on detailed chemical kinetics. It was shown that fast mixing due to strong turbulence enables a great deal reduction in NOx formation, and that NOx concentration can be halved if the temperature decreases with the volume expansion in a high-speed piston-engine motion prior to the heat release due to dilution.2.A high swirl burner was tested to investigate the mechanism of the flame stability and the NOx formation. The obtained results showed that a diffusion flame having the same low-NOx level with that in a premixed flame would be formed under a higher swirl number and a stoichiometric fuel-air ratio. Furthermore, the NOx reduction by means of burnt-gas addition in the diffusion combustion was investigated based on a detailed chemical kinetics. It was shown that the burnt-gas temperature should be reduced during recirculation process to reduce NOx, and that a lower temperature can reduce NOx a great deal.3.Exhaust-water-selective recirculation, which operates as a closed system without a supplementary water charge, was proposed for reducing NOx in diesel engine exhaust. The feasibility of the system was experimentally assessed on a single-cylinder test engine. In addition, the effects of intake-air dilution with N2 and CO2 and EGR on the exhaust emissions were predicted and discussed based on a stochastic model. The predicted results showed that cold EGR does not much affect the average temperature, but diminishes gas pockets having a higher-temperature greater than 2,500K,resulting in a great reduction of NO formation.

这项研究旨在获得减少NOX的建议，并阐明实用燃烧器和电力系统中异质燃烧过程减少的边际限制。本研究的内容总结如下：1。基于详细的化学动力学研究了NOX的生产和破坏。结果表明，由于湍流强大而引起的快速混合可以大大降低NOx的形成，如果温度随着体积的膨胀而在高速活塞 - 发动机运动中的体积膨胀下降低，则NOX浓度可能会减少一半。获得的结果表明，在较高的旋转数和化学计量燃料空气比率下，在预混合火焰中具有相同低NOX水平的扩散火焰将形成。此外，基于详细的化学动力学研究了扩散燃烧中通过燃烧的加气的减少NOx。结果表明，在再循环过程中应降低燃烧气体的温度，以减少NOX，并且较低的温度可以大大降低NOX。3。提议在没有补充水电的情况下以封闭的系统作用，以减少柴油发动机排气中的NOX，作为封闭系统的运行。在单缸测试引擎上对系统的可行性进行了实验评估。此外，根据随机模型预测并讨论了使用N2和CO2和EGR的进气空气稀释对排气排放的影响。预测的结果表明，冷EGR不会影响平均温度，但会降低气口较高的气口大于2500k，从而大大降低了无构造。