Dataset of numerical study of the impact of two-step injection (direct and port) of hydrogen-enriched and natural gas mixtures on engine efficiency and exhaust emissions.

A study was conducted to examine the effects of two-step fuel injection on a modified four-cylinder engine that was converted from port to direct injection. The primary fuel source utilized was hydrogen-enriched compressed natural gas (HCNG), which replaced the conventional gasoline. In the initial phase of the procedure, compressed natural gas (CNG) was introduced into the intake manifold at a concentration of 10 % by mass, relative to the total fuel mixture. The remaining 90 % of the fuel consisted of HCNG, which was injected directly into the cylinders. The injection of compressed natural gas (CNG) commenced at 160° before top dead center (BTDC) with a 20° stroke duration. The HCNG fuel was injected in a two-step process. In the initial phase, HCNG was injected at 130° BTDC with a 50° stroke duration, with a stepwise increase from 0 % to 40 %. The study employed AVL software for the assessment of engine performance, efficiency, fuel consumption, and exhaust emissions. The data collected indicated that the injection of a 30 % HCNG blend resulted in an increase in brake power, brake thermal efficiency, and in-cylinder pressure (from 8 % to 13.64 %), as well as a reduction in specific fuel consumption (by 18 %). This improvement was attributed to an increase in flame propagation speed within the combustion chamber. Additionally, the percentage of excess hydrogen was found to decrease, resulting in a reduction of carbon monoxide and unburned hydrocarbons by up to 14 % due to complete combustion. However, NOx increased due to the rise in exhaust temperature.