Combustion and emission characteristics of RCCI engine fueled with hydrogen and karanja biodiesel renewable fuels

Abstract

In a diesel engine, heterogeneous combustion is more harmful, noisy, and uncontrollable. Reactivity-controlled compression ignition mode engines that run on low and high reactive fuel combinations are a smart way to deal with this. The current work modifies a diesel engine to run on gaseous fuels in reactivity controlled combustion ignition (RCCI) engine mode, namely. The main fuels are hydrogen enriched CNG (HCNG) and hydrogen (H₂), while the pilot fuel is a mixture of diesel and Karanja biodiesel (BD20). Determining the operational limitations of HCNG and H₂ fuels for cleaner emissions and quieter combustion is the goal of this study. Additionally, for full load operation, the relative air-fuel ratio (λ), cycle-to-cycle fluctuations, emissions, and combustion noise were examined. With a split injection approach, the common rail direct injection (CRDI) engine is tuned for diesel operation. The knock limitations for the major fuels, HCNG and H₂, are determined. At injector open time (IOT) 8 ms of LRF, the maximum in-cylinder pressures for HCNG and H₂ are 72 and 76 bar, respectively. Heat release rates of 86 and 87.9 J/deg, respectively, ES75 % and 22 % of LRF HCNG and H₂ were obtained. Using the RCCI mode of a modified diesel engine, an optimal of 75–80 % and 30–40 % ES of HCNG and H₂ LRFs is noted for clean combustion and emissions strategy. At optimum performance HC emissions of 42 and 138 ppm for H₂ and HCNG LRFs respectively were observed. At higher ES of LRF, lower CO emissions of 0.04 and 0.02 % are obtained.