Performance and emissions associated with natural gas injection in Diesel engine operating under dual fuel mode

Abstract

The use of alternative fuels such as compressed natural gas, as dual fuel for the diesel engine, is an interesting object of study and will diversify fuel sources, reduce fuel cost and carbon dioxide emissions. However, there are several issues that need to be considered, such as the specific tuning of the internal combustion engine for that fuel combustion. Also, the addition of a gaseous fuel to the mix will change the predominant properties associated to the combustion characteristics. In this study an experimental analysis of the use of compressed natural gas in a dual fuel Diesel engine connected to an eddy current dynamometer is presented. The present work involves laboratory experiments with these fuels in a light vehicle common-rail Diesel engine and performs a comparison of dual fuel mode to diesel fuels in terms of emissions (unburnt hydrocarbon, carbon monoxide, nitrogen oxide and smoke), torque, power and efficiency. It was necessary to modify the Diesel engine in order to perform the required tests, including changes in its electronic control unit. This was required to control load in order to optimize engine power/efficiency. The aim of reprogramming the electronic control unit in the Diesel engine was to preserve or even increase the original engine specifications, when increasing the incorporation of gaseous fuels, with the additional advantages on fuel consumption, engine efficiency, and reduction of gaseous emissions.