Preliminary results of the transformation of a car's DI diesel engine into a dual fuel one with common rail injection

摘要

A car Diesel engine has been transformed into a dual fuel engine for operation on natural gas. The potential reduction of polluting emissions makes natural gas a very interesting alternative fuel for automotive applications. The aim of he present investigation is the transformation of a D.I. Diesel engine into a dual fuel engine with pilot injection via the common rail injection system used to ignite the CNG-Air charge. The standard injection pump creates some instability of the system that makes the ignition at low flow rates and high engine speed not possible and, consequently, the use of the dual fuel configuration as well. Adopting the new common rail system it has been possible to ignite the fuel in all conditions with an amount of gas oil less than 8% of the entire energy requested by the engine nominal power. In some cases even 3% of the total energy requested by the engine was enough to ignite the fuel. Furthermore, an increase of the power compared to the gas oil fueled engine has been reached with an overall efficiency similar to the standard engine or, in some cases, even better. The paper refers to the experimental investigation carried out on a 1929 cc D.I. turbo-charged engine and presents the preliminary results.