Low Temperature Combustion of Jet Propellant-8 Fuel in Compression Ignition Engine with the Low Compression Ratio

Abstract

Jet Propellant-8 (JP-8) is used as a fuel for a standard Compression Ignition (CI) engine instead of diesel oil, especially in the military applications. The properties of a kerosene-type fuel, which is JP-8, encourage us to test different strategies of mixture creation and combustion which could be more effective for this fuel, than these elaborated for diesel oil. The experiment aimed to show whether it is possible to realise an effective Low Temperature Combustion (LTC) strategy in a CI engine with a low compression ratio for JP-8 fuel. The tests were focused on combustion of a lean homogeneous JP-8/air mixture close to the knock limit. Additionally, the combustion process of the homogeneous mixtures diluted with EGR was examined. AVL research engine with common rail system and low compression ratio (CR=12) was adapted for the tests. In order to create a homogeneous mixture early, multi injection of JP-8 under high (90 MPa) was applied. The results of the HCCI operation were compared to the Partially Premixed Combustion (PPC) mode without EGR, tested on the same engine with a low CR. The experiment showed that it is possible to realise LTC process for the HCCI engine fueled with JP-8, though the knock confined the engine load. The application of EGR allowed to control the phase and rate of the heat release. The higher share of EGR made the HCCI engine cycles less repetitive. Generally, For the HCCI engine operation, CO and total hydrocarbons (THC) emission were on a high level. The PM emission was also relatively high, whereas NOx was maintained on a low level for all of the examined points.

Keywords

• low temperature combustion
• hcci engine
• partially premixed combustion
• jet propellant-8