Abstract
Keywords: Hydrogen Assisted Jet Ignition (HAJI), Lean Burn, Reformed Fuel, Prechamber, Syngas
Gas assisted jet ignition is an advanced ignition process that allows ignition of ultra lean mixtures in an otherwise standard gasoline fuelled spark ignition engine. Under typical operating conditions, a small amount of gaseous fuel is injected into a prechamber and then ignited by a spark plug. Upon ignition, the fuel rich prechamber mixture generates a jet of chemically active combustion products that issue through an orifice, which connects to the main chamber, and burns the main charge rapidly and with almost no combustion variability (less than 2% COVIMEP even at l=2.5). Thus gas assisted jet ignition has many of the desirable qualities of HCCI but with the ability to operate without throttling, EGR or thermal intake management over the entire load-speed range. In order to overcome the refuelling and storage problems associated with H2, the conventional prechamber fuel used in this process, the viability of other prechamber fuels is assessed based on criteria such as combustion stability, lean limit and emission levels. The prechamber fuels tested consist of syngas or simulated reformed petrol (CO, H2 and N2) and variants of reformed fuel with different component ratios.