Enhancement performance and exhaust emissions of rapeseed methyl ester by using n-hexadecane and n-hexane fuel additives

A lot of studies were conducted in recent years to improve of biodiesel performance. It has been stated that the addition of additives in biodiesel reduces emissions of unburned hydrocarbon (HC), carbon monoxide (CO) and particulate matter (PM). It makes a significant improvement in thermal efficiency (BTE) and heat dissipation rate (HRR). The additives are attractive in automotive applications due to their excellent phase stability and clean combustion ability. Engine performance and exhaust emissions are mainly based on air-fuel ratio, cetane number, oxygen content of fuel, fuel atomization and the other features. In this study, two different additives were added to the biodiesel to change the number of cetane. In addition, engine performance and emission changes were investigated experimentally. The viscosity and density of fuels were reduced by additives. Compared to R0 fuel, torque increased by 9.74% and 7.22% in RHD20 and RHX20 fuels respectively. While specific fuel consumption decreased by 9.58% and 6.50% respectively. The ignition delay and combustion times decreased due to combustion quality. Maximum cylinder pressure and heat release rate values increased after additives adding in fuels. With the increase of the additive rate, HC (RHD20 23.68%, RHX20 21.05%), CO (RHD20 16.89%, RHX20 15.81%), and soot (RHD20 34.35%, RHX20 26.19%) emissions reduced while NOx (RHD20 2.26%, RHX20 3.21%) emissions increased. •n-hexadecane and n-hexane additives were added into biodiesel to improve properties of biodiesel.•Combustion, performance and emission characteristics were examined.•In RHD20 fuel 9.74% torque increase obtained and 7.22% increase in RHX20 fuel.•Addition of additives was increased cylinder pressure and ignition delay reduced.•CO, HC and smoke emissions decreased while NOx emissions increased partially.