Numerical Simulation Of The Effect Of Non-equilibrium Plasma On The Combustion Of Gasoline And Methane

Lean combustion technology is proposed with the energy shortage and environmentalpollution which is caused by the economic development. Lean combustion technologycan improve fuel efficiency, saving energy and reduce air pollution. However, with theincrease of air-fuel ratio, the premixed gas close to the flammable limit can lead toun-properly combustion. In order to ensure an reliable ignition and a normal combustionof lean fuel-air mixture, a special ignition measures must be taken to enhance thecombustion and increase the flame speed. Non-equilibrium plasma has been proved tobe an efficient way for the combustion enhancement of lean fuel air mixtures for thereason that it can both raise the temperature and increase the radicals’ concentration.In this paper, ignition of high-voltage nanosecond pulsed plasma for gasoline andmethane engine have been studied numerically. Discharge process and followingchemical reactions were simulated separately because of an essential difference in theirtime scales. A package ZDPlasKin, which coupling component concentration equation,the energy transfer equations and electronic Boltzmann equation, was used to calculatethe discharge process. The time-resolved particle number densities calculated forZDPlasKin are then imposed as an initial condition for a multi-zone chemical kineticmodel. The effect of discharge on the combustion of gasoline and methane is studied,and the essential reason of plasma assisted combustion in aspects of reaction rates andreaction paths of main particles is revealed.It turned out that, the non-thermal plasma generated by the discharge can promote thecombustion of gasoline, and reduce the period from ignition till the mass burned ratioreaching10%(θ IGN-MB10%). As compared with the fuel rich mixture, thecombustion enhancement of non-equilibrium plasma for lean mixture is morepronounced.The non-thermal plasma generated by the discharge can promote the combustion ofmethane/air mixture, reduce the period of θ IGN-MB10%, and advance the ignitiontime of central region, which illustrates that the non-equilibrium plasma can promotethe lean combustion of methane as well.