Journal Article
A CFD Study of Fuel Evaporation and Related Thermo-fluid Dynamics in the Inlet Manifold, Port and Cylinder of the CFR Octane Engine
2012-09-10
2012-01-1715
Knock in Spark Ignited (SI) engines has received significant research attention historically since this phenomenon effectively restricts the compression ratio and hence the thermal efficiency of the engine. The latent heat of vaporization (LHV) of a fuel affects its knock resistance in production engines as well as affecting its Research Octane Number (RON) rating. The reason for this is that evaporative cooling of the fuel lowers in-cylinder gas temperatures resulting in reduced tendency for end-gas auto-ignition. Controlling of the fuel-air mixture temperature to 422 K at the inlet port as per the Motor Octane Number (MON) test method ensures full evaporation of the liquid fuel, and hence LHV is assumed to have little effect during this procedure. LHV therefore has a strong influence on a fuel's Octane Sensitivity (OS) - the difference between its RON and MON values.
