Analysis of Engine Characteristics and Emissions Fueled by In-situ mixing of Small amount of Hydrogen in CNG

This paper examines the performance and emission of a direct injection (DI) spark-ignition engine when a small amount of hydrogen (0%, 3%, 5% and 8%) is added to the CNG using in-situ mixing. The study was carried out on a CNG-DI, four-stroke single-cylinder research engine. The injection timing was set to 300° BTDC, the air-fuel ratio was kept at stoichiometric (lambda = 1.0), while the ignition timing was adjusted to obtain the maximum brake torque. The experiments were performed at low, optimum and high engine speeds of 2000, 3000, and 4000 rpm with each one operating at wide open throttle (WOT) conditions. The results showed that the introduction of a small amount of hydrogen had improved the engine performance, Brake Specific Energy Consumption (BSEC), and cylinder pressures as well as emissions at low engine speed. In general, significant changes have been observed with the engine characteristics at low engine speed but the rate of increase/decrease of the parameters decreased was less significant with the addition of higher percentages of hydrogen as well as with the increase in engine speeds.