Single Fuel Research Program Comparative Results of the Use of JP-8 Aviation Fuel versus Diesel Fuel on a Direct Injection and Indirect Injection Diesel Engine

During the last years a great effort has been made by many NATO nations to move towards the use of one military fuel for all the land-based military aircraft, vehicles and equipment employed on the military arena. This idea is known to as the Single Fuel Concept (SFC). The fuel selected for the idea of SFC is the JP-8 (F-34) military aviation fuel which is based upon the civil jet fuel F-35 (Jet A-1) with the inclusion of military additives possessing anti-icing and lubricating properties. An extended experimental investigation has been conducted in the laboratory of Thermodynamic and Propulsion Systems at the Hellenic Air Force Academy. This investigation was conducted with the collaboration of the respective laboratories of National Technical University of Athens and Hellenic Naval Academy as well. The main scope of this investigation is to evaluate the use of JP-8 aviation fuel as a full substitute for Diesel Fuel in various types of diesel engines, namely Direct and Indirect Injection Diesel Engines respectively. The present contribution is a review work concerning experimental data for performance and exhaust emissions coming from the operation of the two types of diesel engines with JP-8 fuel. Specifically, the present work covers a range of engine load and speed operating conditions under JP-8 and normal diesel operation (baseline conditions), comprising measurements of cylinder pressure and Injection pressure diagrams, fuel consumption and the concentrations of exhaust gas emissions (Nitrogen Oxide (NO), Carbon Monoxide (CO), Unburnt Hydrocarbons (HC) and Soot) for both types of engines. The differences in the measured performance and exhaust emissions data are determined for the JP-8 fuel engine operation against the normal diesel operation. According to the results presented in this work, for both types of engines (DI and IDI) examined it is revealed a significant effect of JP-8 fuel combustion on some basic engine operating parameters (maximum combustion pressure, ignition delay period etc.) compared to standard diesel operation. As far as the exhaust emissions are concerned, the full substitution of diesel fuel with JP-8 affects positively (reduction) the values of the Carbon Monoxide concentrations while it seems to have a negligible influence on the concentrations of Nitrogen Oxide emissions for both types of engines. On the other hand the operation of each type of engine with JP-8 fuel seems to affect seriously the values of the unburnt hydrocarbons and soot emission concentrations compared to the respective values observed under normal diesel operation.