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Abstract
In this experimental study, a novel combustion technique, “reactivity-controlled compression ignition” (RCCI), has been investigated using alcohols acting as low-reactivity fuel (LRF) and mineral diesel acting as high-reactivity fuel (HRF). Combustion experiments were performed in a single-cylinder research engine at a constant engine speed of 1500 rpm and a low engine load of 3 bar brake mean effective pressure (BMEP). RCCI combustion is a practical low-temperature combustion (LTC) concept, which was achieved using three primary alcohols: Methanol, Ethanol, and Butanol in different premixed ratios (rp = 0.25, 0.50, and 0.75) with mineral diesel. Results showed a relatively superior performance and emissions characteristics of RCCI combustion than the conventional compression ignition (CI) combustion. The influence of LRF was visible in the RCCI combustion, which exhibited a more stable combustion than the baseline CI combustion. Retarded start of combustion (SoC) with increasing rp was exhibited by all alcohols; however, this trend was more dominant for Methanol/diesel- and Ethanol/diesel-fueled RCCI combustion. The presence of moisture traces in Ethanol was clearly observed in Ethanol/diesel-fueled RCCI combustion. Butanol/diesel-fueled RCCI combustion showed more significant similarity with conventional CI combustion at the lower rp. RCCI combustion-fueled with different alcohols produced relatively lower emissions of oxides of nitrogen (NOx); however, hydrocarbon (HC) and carbon monoxide (CO) emissions were higher than that of baseline CI combustion. Among different alcohols, Methanol/diesel and Ethanol/diesel showed a higher reduction in particulate matter (PM) emissions than the Butanol/diesel-fueled RCCI combustion. At higher rp, particulate characteristics of RCCI combustion were similar to that of spark ignition (SI) engines. Correlation between the total particulate mass (TPM) and the NOx emissions showed a strong possibility of significant emission reduction by employing RCCI combustion in the engines while ensuring energy diversification and use of biofuels in an efficient manner. 1212 total citations on Dimensions.
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