Particle Number in Small SI Engine Using Gasoline and LPG as Fuel for Non-road Vehicle

This study measured the particle number (PN) emissions from spark ignition (SI) engines according to the use of gasoline fuel and liquefied petroleum gas (LPG) fuel for particles greater than 23 nm or 5 nm. A 0.8-L two-cylinder gasoline engine, which has variable valve timing system and electronic control unit, was used in the experiment. The engine was operated at 1500 rpm, 3000 rpm, low load, and high load, and the fuel injection timing, intake valve opening timing, exhaust valve closing timing, and valve overlap period were used as variables in the experiment. According to the experimental results, the gasoline engine emitted particulate matter (PM) is in the range of 1 × 10 9 to 3 × 10 13 #/kWh, whereas that of the LPG engine is in the range of 1 × 10 9 to 1 × 10 11 #/kWh. For the LPG engine, the operating conditions and experimental variables had minimal influence on the PN, whereas for the gasoline engine, the experimental conditions and experimental variables had a significant influence on the PN. For this test engine, the ratio of PM smaller than 23 nm increased as the emissions of PM larger than 23 nm decreased, which were observed for values between 1 × 10 10 #/kWh and 1 × 10 11 #/kWh.