Experimental investigations on a hydrogen diesel homogeneous charge compression ignition engine with exhaust gas recirculation

•HCCI with hydrogen induction, diesel injection realized without heating inlet air.•High thermal efficiency with low emissions in a BMEP range of 2–4 bar achieved.•Proper combustion phasing was abtained by suitable hydrogen to EGR ratio.•Best hydrogen, diesel and cold EGR proportions were identified at different outputs.

In this experimental study, hydrogen was inducted along with air and diesel was injected into the cylinder using a high pressure common rail system, in a single cylinder homogeneous charge compression ignition engine. An electronic controller was used to set the required injection timing of diesel for best thermal efficiency. The influences of hydrogen to diesel energy ratio, output of the engine and exhaust gas recirculation (EGR) on performance, emissions and combustion were studied in detail. An increase in the amount of hydrogen improved the thermal efficiency by retarding the combustion process. It also lowered the exhaust emissions. Large amounts of hydrogen and EGR were needed at high outputs for suppressing knock. The range of operation was brake mean effective pressures of 2–4 bar. The levels of HC and CO emitted were not significantly influenced by the amount of hydrogen that was used.