低温等离子体辅助燃烧的研究进展、关键问题及展望

Progress, Key Problems and Prospect on Low Temperature Plasma Assisted Combustion

利用低温放电等离子体在各种极限条件下实现快速点火,稳定燃烧和提高燃烧效率减小对环境的污染是近年来等离子体应用研究的热点之一。基于相关研究现状,归纳了低温等离子体辅助燃烧的机理,从实验研究、仿真计算、ns重频脉冲电源研制等各方面,介绍并讨论了这些研究的进展。目前一般认为等离子体化学反应产生的活性基团和气流温升是提高燃烧效率的主要因素,尤其是氧原子对燃烧过程影响较大。作为物质第四态的等离子体具有快速的热效应、比较高的自由电子能量和一些长寿命激发态粒子,且在放电过程中等离子体对流场的影响会改变气体的输运特性。这些共同因素的作用使得燃料气体的电离及输运时间缩短,能够有效降低点火温度,提高燃烧效率,拓展燃烧极限。在实验研究方面,介绍了各研究机构独特的燃烧器设计方案和相关参数,分析了不同电极结构和放电形式对燃烧的影响。最后提出在未来的研究中,应重点关注的问题包括:流动环境下大气压均匀等离子体的产生;大气压低温等离子体的非介入式测量与诊断;等离子体辅助燃烧的建模与仿真;等离子体激发电源的研制。

Low-temperature discharge plasma-assisted combustion has become a research hotspot to achieve rapid igni- tion and stable combustion in a variety of extreme conditions. On the basis of the reported researches, we summarize the relevant mechanisms of low-temperature plasma-assisted combustion, present and discuss the progress of these studies from the aspects of experimental research, simulation, ns repetitive pulsed power supply, etc. Currently, it is widely be- lieved that active radicals and air temperature rising due to plasma chemical reactions, especially those involving oxygen atoms, are the main factors to improve the combustion efficiency. As the fourth state of matter, plasma has its unique fea- tures, such as fast thermal effect, high-energy electrons, and long-life excited-state particles, and in discharge processes, gas transport properties will be changed because of the change of flow field. These factors together speed up fuel gas io- nization and transportation, and consequently reduce the required ignition temperature, improve the combustion efficiency, and expand the combustion limit. In the aspects of experiment, we introduce some unique burner designs and related pa- rameters, and analyze how their electrode structures and discharge forms affect combustiol~. Finally, it is proposed that, for future studies, attention should be focused on issues including uniform plasma generation in ambient atmospheric flow, non-intrusive measurement and diagnosis of plasma under low temperature atmospheric pressure, modeling and simula- tion of plasma-assisted combustion, and the development of plasma generation power supply.