THE USE OF INTAKE CONDITION MODIFICATIONS TO CONTROL DIESEL EMISSIONS

摘要

Diesel engines have the inherent capability of producing emissions, such as NOx, particulates, unbumed hydrocarbons, and noise which at certain levels and concentrations are considered to en vironmentally unfriendly. To control these emissions, techniques have been developed which are aimed at reducing the amount of pollutants formed in the combustion process or preventing them from reaching the atmosphere (after treatment). The initial condition of the in-cylinder reactants and diluents affects how the combustion process proceeds and hence influences the formation and rate of formation of the pollutants. Thus, one approach to emission control is to modify the intake oxidant conditions, i.e., the composition and thermodynamic state of the working fluid. This modification can be accomplished by the use of exhaust gas recirculation (EGR).EGR has been extensively developed for use with SI engine emission control systems and for specialised diesel engine operations where synthetic atmospheres are used (underwater) or where operations take place in contaminated environments (underground). More recently EGR has been considered as a technique for helping reduce NOx emissions from conventional diesel engine systems. Usually, experimental investigations involving EGR have dealt with the global effects on emissions and performance but in the research reported in this paper efforts have been made to identify the specific effects of altering intake conditions, e.g., oxygen concentration, on the operation of an Indirect-Injection (IDI) diesel engine.