Effect of Varying Flowrate of Oxy-hydrogen (HHO) Gas Addition on Combustion and Emission Characteristics of Early Direct Injection Homogenous Charge Compression Ignition Engine

Early Direct Injection Homogenous Charge Compression Ignition (HCCI) helps in the reduction of NOx and smoke emissions. However, this strategy gives out higher carbon monoxide and hydrocarbon emissions with less power and fuel economy. To address this issue, experiments were carried out to investigate the effect of addition of oxy-hydrogen (HHO) gas in compression ignition engine with injection advance. The fuel injection timing and pressure were set to 45 bTDC and 600 bar, respectively. The production of HHO gas was done by the electrochemical splitting of water by electricity, and it was added in the intake manifold with a variable flow rate. The combustion and emissions characteristics were measured with a change in load at a constant speed. The In-cylinder Peak Pressure and Net Heat Release Rate improved with HHO gas addition. The ignition delay periods were longer, and combustion duration was reduced. Carbon Monoxide, Oxides of Nitrogen, and smoke opacity were reduced with the higher flow rate of HHO gas. However, Hydrocarbon and Carbon Dioxide emissions increased with the higher flow rate of HHO gas.