Analysis of combustion process in a dual-fuel compression ignition engine fuelled with LPG in the liquid phase

Investigation on fuelling a dual-fuel compression ignition engine with various fuels, that are unconventional for this type of engine, was carried out for many years in the Department of Internal Combustion Engines and Automobiles in Technical University of Radom. Such fuels as methanol, ethanol and natural gas were applied in the investigation. Recently, the investigation regards application of LPG - a fuel that is very popular in Poland. Within the project No. 4T12D02226 of the Committee of Scientific Research, it was tested, among others, an engine equipped with injection system for diesel fuel pilot dose - a common rail type. As a result of the former investigation, load characteristics of specific energy consumption as well as CO, CO2, nox, HC and smoke emissions data were obtained [1]. In order to analyze variability of fundamental combustion process parameters, histories of the pressure inside combustion chamber have been registered during investigation. Investigation on changes of these parameters in the described engine version is particularly important due to possibility of knocking combustion occurrence that leads to the failure of such engine parts as piston or valves. Changes of these parameters versus engine load for various injection timing of diesel fuel pilot dose were analysed.