Numerical investigation of hydrogen-diesel dual fuel engine: Combustion and emissions characteristics under varying hydrogen concentration and exhaust gas recirculation

Abstract

This study investigates the impact of hydrogen addition and exhaust gas recirculation on combustion characteristics and emissions in a diesel-hydrogen dual-fuel engine. A 3D CFD model of a heavy-duty diesel engine is utilized under full load and constant speed conditions at 1600 rpm. Hydrogen is introduced into the intake system at varying percentages 0 %, 10 %, 20 %, 30 %, 40 %, and 50 % of total thermal energy, while exhaust gas is utilized at 5 % and 10 % of gas intake volume with 40 % hydrogen. Results show that increasing hydrogen percentage enhances engine efficiency. CO and soot emissions decrease significantly up to 33 % and 88 %, with 50 % H2 and 40 % H2 addition respectively, while NOX emissions increase notably by 57 % at 50 % hydrogen. Additionally, utilizing exhaust gas at 10 % intake volume effectively reduces NOX emissions but caused CO to increase. These findings underscore the substantial influence of hydrogen percentage on combustion characteristics and emissions formation, emphasizing the potential for emissions mitigation and improved combustion efficiency in dual-fuel engines.