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Abstract

Low-Temperature combustion (LTC) has demonstrated huge potential to simultaneously control nitrogen oxide (NOx) and particle matter (PM) significantly in automotive engines. Hydrocarbons (HCs) and carbon monoxide (CO) are key challenges due to low combustion temperatures in dual fuel combustion. The selection of diesel oxidation catalyst (DOC) and precious group metal (PGM) content is critical for low-temperature combustion (dual fuel) to control HC and CO emissions norms. An experimental test bed study was conducted in a 3.8 litre diesel common rail engine with a gasoline port injection to evaluate the after-treatment strategy in low and high-reactive fuel. Three DOCs with different PGM content were tested along with different dual fuel compositions to understand their effectiveness and particle matter composition. The chemical composition of exhaust particles from engine Out and DOC out are compared. An increase in low reactive fuel (D15G85) and an increase in PGM content highlights a significant reduction in PM from 31 mg/kWhr to 2 mg/kWhr. The major reduction in particle size distribution observed with high PGM loading is 40 nm with a dual fuel configuration of D15G85 as the best approach to meet emission standards. Additionally, a detailed study was made to investigate the characteristics of particle mass and particle size distribution in the engine and after-treatment emissions. The particle number (PN) and their correlation for engine out, DOC Out, and DPF out emission are demonstrated with different dual fuel combinations of D50G50, D25G75, and D15G85 compared with diesel fuel. To comprehend its characteristic of particle number and particle mass correlation, dual fuel is tested in different ratios. A linear correlation of PM and PN emissions is observed between engine out and DOC out as particulate diameter of the particle size with the total number concentration of particles in engine and DOC out. The nonlinear trend is observed for DPF out due to small particle size (around 5nm) with different ratios of dual fuel. Particle matter filter paper analyses were performed to understand chemical composition with different DOCs and dual fuel ratios to understand Soluble Organic Fraction (SOF) and Insoluble Organic Fraction (IOF) content.