THE INFLUENCE OF HEAT RELEASE AND THE COMBUSTION CHAMBER SHAPE ON THE CONCENTRATION OF UNBURNED HYDROCARBONS IN THE EXHAUST GASES

The paper presents the results of experimental studies of the influence of heat release and the combustion chamber shape on the concentration of unburned hydrocarbons in the exhaust gases of reciprocating electric power plants with spark ignition. The authors determined that the increase in the combustion chamber area causes the increase in the unburned hydrocarbons concentration due to the increase in the area of near-wall layers formed on the combustion chamber walls. Moreover, it was noted that, except the combustion chamber shape, the process of fuel combustion in the final phase of combustion, the intensity of which was estimated by the heat release value, played the important role in the mechanism of unburned hydrocarbons formation. The analysis of experimental data showed the tendency of reduction of the unburned hydrocarbons concentration with the heat release increase. The authors also revealed the reasonability of application of complex influence of fuel-air mixture composition, the combustion chamber design, and the processes in it on the unburned hydrocarbons dynamics. The authors proposed using the K parameter complex considering the influence of carbon, hydrogen and oxygen mass fractions in the fuel mixture, the combustion chamber area, and the heat release during combustion final phase on the unburned hydrocarbon emission. It is expected that the measures aimed to increase thermal power density and to reduce carbon concentration in the fuel-air mixture will reduce K, and the unburned hydrocarbons concentration as well. The authors received the linear relationship between the proposed K parameter complex and the unburned hydrocarbons concentration. Thus, the use of K complex during the stages of design and operational development of power plants will allow evaluating the effectiveness of design solutions aimed to improve environmental performance.