Experimental investigation on the combustion and emissions characteristics of an N-butanol/CTL dual fuel engine

•First study on N-butanol/CTL dual fuel combustion.•Dual fuel combustion features lower NOx and PN than single-fuel combustion.•The combined results of combustion and emissions have been further improved by optimizing combustion boundary conditions.•Increasing the n-butanol ratio promotes the conversion of particulate to nuclear mode.