Numerical Study of the Influence of the Photochemical Activation of Oxygen Molecules on Homogeneous Charge Compression Ignition Performance

Numerical analysis of the possibility of the combustion enhancement in a homogeneous charge compression ignition (HCCI) engine operating on methane via the production of O₂(a¹Δ_g) molecules or O atoms by resonance laser radiation in the 5 mm thickness layer, located near the cylinder head, is conducted for both the nominal- and low-load regimes. It is shown that the abundance of both singlet delta oxygen and atomic oxygen in such a layer substantially accelerates ignition phasing, enhances the combustion, and reduces the pollutant emission. Moreover, the advance in the specific work in these cases is higher than the energy put into the gas for producing O₂(a¹Δ_g) molecules or O atoms. In doing so, the production of O₂(a¹Δ_g) molecules is more effective for the combustion enhancement in a HCCI engine. At a low-load regime, the production of O₂(a¹Δ_g) molecules makes it possible to extend the range of stable combustion, to increase notably the engine power (by a factor of 1.4), and to reduce by a few times the emissions of CO, unburnt hydrocarbons, and organic compounds.