Aspects of in-Cylinder Mixture Formation Study for a Diesel Engine Fuelled with LPG by Diesel-Gas Method

Abstract

The Liquid Petroleum Gas can be use for diesel engine fuelling with significant result in term of pollutant emissions improvement, with important reduction of nitrous oxides and smoke for a LPG dual fuelled diesel engine. Beside this the LPG fuelling affects the combustion process inside the cylinder and also the mixture forming. High degree of homogeneity of the air-LPG mixtures will accelerate the in-cylinder mixture forming between air-LPG and diesel fuel jets, since the LPG-air mixture combustion starts. The paper presents the results of a zero-dimensional, one-zone thermodynamic model developed by authors for diesel fuel jets vaporization and combustion at dual fuelling. The model shows the diesel fuel jet characteristic, the break-up period, the mass flow of vaporized substance on the particle surface, drops vaporization time, air-fuel mixture forming speed, drops combustion time and flame position, showing a significant influence of LPG cycle dose on their characteristic parameters. The drops vaporization and combustion duration decrease for dual fuelling and the flame radius increases. Thus, based on the experimental data, an evaluation model for mixture forming was developed for an automotive diesel engine fuelled with LPG and diesel fuel by diesel-gas method.