I am very confused that which kind of plasma is more appropriate to assist combustion and how to judge it.
The non-thermal plasma is said to assist the combustion with less energy consumption than the thermal plasma. But is it really true under any conditions?
Also the non-thermal plasma could be produced with different methods like DBD, gliding arc, rf, microwave etc. Which one is better or how to choose the right one in the practice? Could you give me some examples and suggestions. Thank you!
It depends. I suggest you do some sensitivity analysis of detailed elementary reactions which include electrons. as you may know, scattering time of electron is very short, but it is very long for ions and other heavy species(almost 3 orders ). From this point of view, non-thermal plasma only has effect in very short time (~ns at 1 atm), but this can active many species. I have to go.
Beware. Even if most chemical species are basically at local thermodynamical equilibrium e.g. in lean premixed combustion, those species whose reactions involve free electrons (notably, CHO ions) do not satisfy such requirement and require dedicated, detailed kinetic treatment. Assessing plasma impact on combustion requires therefore such treatment, even if the plasma of choice is a thermal plasma.
Plasma provides an unprecedented opportunity for combustion and emission control owing to its unique capability in producing active species and heat and modifying transport processes. New reaction pathways, such as atomic O production from the collisions between high energy electrons/ions and oxygen molecules, can be introduced into combustion systems to modify the fuel oxidation pathways considerably.
Plasma is a collection of neutral and charged particles which are electrically neutral on average and exhibit collective effects.
There are two types of plasmas, one is the equilibrium plasma in which the electron temperature, rotational and vibrational temperatures of particles are in equilibrium and the neutral gas temperature and electron number density are very high.
The plasma torch and spark plugs belong to this category.
The other is the non-equilibrium plasma in which the electronic, vibrational, and rotational temperatures are very different and the neutral gas temperature and electron number density are relatively low.
Plasmas such as microwave discharge, dielectric barrier discharge, gliding arc, streamer discharge, and glow discharge belong to this category.
Compared to equilibrium plasma, non-equilibrium plasma has higher electron temperature (1–100 eV) and is more kinetically active due to the rapid production of active radicals and excited species via electron impact dissociation, excitation, and subsequent energy relaxation.
Hope you can now select the plasma for your pupose.
How can one ensure that the combustion efficiency of a gas turbine using plasma will be higher than that of conventional methods. Also, how to ensure that the emission levels (especially NOx) are reduced compared to conventional method?
- Badges
- Science topic
- Similar topics
- Geoscience
- Asia
- India