MODELING OF DIRECT-INJECTION DIESEL-ENGINE COMBUSTION AND EMISSIONS -AN EASY AND RELIABLE METHOD

Modelling of combustion and emission phenomenon in diesel engines is o n the cross roads. Because of the availability of super computers, hig hly sophisticated multi-dimensional models are being developed making global thermodynamic models obsolete. However, multi-dimensional model s are quite expensive from the point of view of memory and computer ti me, whereas simple thermodynamic models lack accuracy. Ln this paper, a via media approach between the global and multi-dimensional models i s attempted. The model employs a two-zone approach dividing the combus tion chamber into burning and non-burning zones. The burning zone is i dentified by the spray characteristics and air entrainment. Formulatio n and solution of energy and mass conservation equations in the spray zone and the rest of the cylinder results in the determination of burn ing zone, non-burning zone and the average cylinder gas temperatures. This helps in the prediction of thermal efficiency and most importantl y the emission characteristics.