performance combustion and emissions characterization of partially premixed combustion strategies of n butanol diesel blends in a multi cylinder common rail direct injection engine

Abstract

The main objective of this research was to effectively employ the n-butanol fuel in an advanced combustion strategy, partially premixed combustion (PPC) , and provide the maximum possible replacement of diesel fuel. An experimental study was performed on a multi-cylinder turbocharged intercooler CRDI engine to optimize the diesel/n-butanol blended fuels, injection timings, pilot/main fuel ratio, pilot-main interval and fuel injection pressure based on performance, emissions, and combustion characteristics, including cyclic variability to achieve the PPC strategy without giving a significant penalty on thermal efficiency. After optimizing the injection timing and n-butanol/diesel blends. The combustion characteristic analysis indicates that adding n-butanol fuel into diesel fuel, combined with advanced injection (16° CA BTDC) timing, leads to a drastic decrease in smoke emission as well as an increase in NOX emission compared to diesel fuel. However, DB20 fuel at 8° CA BTDC injection timing achieved low-temperature PPC mode and reduced NOX (8.08%and#8595;) and smoke (48%and#8595;) emissions simultaneously compared to diesel fuel at 2 bar BMEP engine load. Apart from that, wavelet power spectrum (WPS) and global wavelet spectrum (GWS) analysis have been used to analyze the temporal and spectral variations in the partially premixed combustion parameter (indicated mean adequate pressure) at optimum injection timing (8° CA BTDC). Results reveal that DB20 possesses lesser cyclic variations with higher frequency (at period 2-6 cycles) intermittent fluctuation in partially premixed combustion at 2 bar BMEP engine load than other tested fuels. DB20 fuel may be used in PPCI engines without requiring any modifications to achieve higher brake thermal efficiency, a significant reduction in NOX and soot emissions, and improved combustion stability. Results indicated that the early start of injection (SOI) timing of 12º CA BTDC has a lower standard deviation in the time-series data of IMEP than the late SOI timing. Moreover, when