Progress, key problems and prospect on low temperature plasma assisted combustion

Low-temperature discharge plasma-assisted combustion has become a research hotspot to achieve rapid ignition 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 believed 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 features, 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 ionization 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 parameters, and analyze how their electrode structures and discharge forms affect combustion. 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 simulation of plasma-assisted combustion, and the development of plasma generation power supply.