Effect of hydrogen addition on combustion, performance and emission of stoichiometric compressed natural gas fueled internal combustion engine along with exhaust gas recirculation at low, half and high load conditions

Abstract

Petrochemicals are the main source of pollution that can be controlled with the implementation of hydrogen fuel in transportation sector due to the property of carbon free structure. In the present study, experiments of gas engine have been conducted under a wide range of hydrogen percentages (0–50% in volume) in CNG fuel, EGR rates (0–26%), spark timings (14-42°CA bTDC) and loads (25%, 50% & 75%) at stoichiometric operating condition. Performance and emissions of compressed natural gas fueled internal combustion engine has been achieved and analyzed at different EGR rates and ignition timings at stoichiometric combustion and half load condition. These parameters have been further studied with the enrichment of hydrogen fractions in CNG fuel, regulation of EGR ratios and spark timings at low, half and high loads. Total ten parameters have been investigated that included: brake thermal efficiency, cyclic variation, in-cylinder pressure, temperature, mass fraction burned, heat released rate, NOx, carbon monoxide, total hydrocarbon, and methane emissions to evaluate the fitness of laboratory-based spark ignition CNG engine. Engine’ emissions have been analyzed with respect to emission mechanisms simulated by GRI Mech3.0.Maximum brake timing advances by 2° to 3°CA with each addition of EGR ratio by 3%, while it retarded by the same angle with each enrichment of 10% hydrogen fraction in compressed natural gas. The smaller H2/EGR ratio (HCNG10 & EGR = 10%) is the best mixture at low load conditions, medium H2/EGR ratio (HCNG50 & EGR = 14%) is suitable for half load conditions and larger H2/EGR ratio (HCNG50 & EGR = 26%) is appropriate charge composition for high load conditions.