Impact of isopropanol butanol ethanol biodiesel diesel blends on combustion and emissions in a diesel engine with DOC SCR aftertreatment

Diesel oxidation catalysts (DOC) and selective catalytic reduction (SCR) systems are widely used effective aftertreatment technologies for reducing exhaust emissions from diesel engines. Isopropanol–Butanol–Ethanol (IBE) blends and safflower oil biodiesel are among the alternative fuels that support combustion and offer emission-reduction potential due to their high oxygen content and renewable properties. In this study, the effects of IBE, safflower oil biodiesel, and diesel fuel blends on engine performance, combustion characteristics, and exhaust emissions were experimentally investigated using DOC and SCR systems. The experiments were conducted at a constant engine speed of 1800 rpm with eight test fuels (Diesel, IBE5D95, IBE10D90, IBE15D85, B30, B30IBE5D65, B30IBE10D60, and B30IBE15D55) and four engine loads (10.98, 16.48, 21.97, and 27.46 Nm). The addition of biodiesel and IBE increased the fuel’s oxygen content and significantly improved combustion. The addition of IBE to diesel fuel has prolonged the ignition delay (ID) and significantly altered cylinder pressure and the maximum pressure rise rate (MPRR) by increasing heat release during the premixed combustion phase. The addition of biodiesel and IBE reduced carbon monoxide (CO) and hydrocarbon (HC) emissions, while nitrogen oxide (NOx) emissions increased due to the increased oxygen content in the fuel. DOC use achieved conversion efficiencies of up to 100% for CO emissions and 35% for HC emissions. The SCR system reduced NOx emissions by up to 76% and brought exhaust emission values closer to regulatory limits.