Premixed-compression-ignition natural gas engine
It is proposed that a premixed-compression-ignition natural gas engine could be realized by gaseous formaldehyde addition into the intake fuel/air mixtures. Large-scale natural gas engines could not be realized even by prechamber-type, spark-ignition engines due to knocking and/or flame propagation problems, nor by diesel operations due to poor ignition characteristics of the fuel. The formaldehyde addition would show a strong promoting effect for lean mixture ignition of natural gas. When suitable amount of formaldehyde is added into the intake fuel/air mixture the piston compression ignition will occur adequately near the top dead center. Confirmation experiments of the proposed concept were carried out herewith using a single-cylinder engine and a commercial natural gas 13A as fuel.