The Investigation of Combustion and Emissions of Jp8 Fuel in an Auxiliary Power Unit

The US Army Single Fuel Forward policy mandates that deployed vehicles must be able to operate with aviation fuel JP-8. It is for this reason that it is vital that an investigation into the impact of JP-8 on a diesel engine performance be conducted. The author investigated the injection, combustion, and performance of JP-8, 20-50% by weight in diesel no. 2 mixtures in a small indirect injection, 77mm separate three vortex combustion chamber engine, with a high compression ratio, in order to evaluate its\u27 effectiveness for application in Auxiliary Power Units (APUs). The new fuel mixtures were created at room temperature. For proper injection, the diesel engine requires a fuel viscosity between 1-10cSt, therefore, the new fuel can contain up to 100% JP-8 (J-100). This was verified by the piston-plunger type pump injection system. All blends were shown to have a good ignition with the ignition delay remaining constant in correlation with the amount of JP-8. The heat release for all blends displayed a similar development compared with the diesel fuel, the premixed phase being combined diffusion combustion. The maximum combustion pressure remained relatively constant for all fuel blends. The maximum temperature shifts later in the crank angle as JP-8 percentage increases, all the while retaining a higher temperature for a longer duration. The exhaust temperatures remained relatively constant for all blends. The heat flux in the engine cylinder showed similar values for all fuels, while the cylinder heat losses were at a minimum during combustion before TDC with increased convection losses at TDC for all fuels and first part of power stroke. The heat losses associated with the system increased slightly with the addition of JP-8 without any shifts extending for the duration of cycle. The engine investigation demonstrated that up to 50% JP-8 by weight in diesel can be injected and burnt in a diesel engine at a residence time of 5ms from the start of injection, while maintaining the overall efficiency performance. The study validates that the JP-8 is an excellent source for power generation in a diesel APU (auxiliary power unit) based on its combustion characteristics