Experimental Investigation for Accessing the Effect of Preheating of Biodiesel Blend (B20) on Performance and Emission Characteristics of a 10-kW Diesel Engine

The purpose of the current study was to carry out an experimental evaluation of the performance and emission profile of a 10-kW water-cooled direct injection four-stroke single-cylinder diesel engine using diesel, B20 (80% v/v diesel and 20% v/v palm biodiesel), and HB20 (B20 at 55 °C preheating temperature) as a fuel. The performance and emission profile of an engine were evaluated in terms of exhaust gas temperature (EGT), brake specific fuel consumption (BSFC), brake thermal efficiency (BTE), carbon monoxide (CO), hydrocarbon (HC), and oxides of nitrogen (NO_x). During the experimental investigation, the engine was operated at constant loads (0, 25, 50, 75, and 100%). Palm oil was used for producing biodiesel (B100) following transesterification using potassium hydroxide (KOH) and methanol (CH₃OH). A separate external fuel preheating system was developed to supply preheated fuel to the engine at a specific temperature. This experiment determined a preheating temperature of 55 °C for B20 because, at this temperature, HB20 exhibited diesel-like viscosity and density. The engine performance and fuel characteristics (density and viscosity) were enhanced while emissions (CO and HC), excluding NO_x, were reduced for HB20 (B20 at 55 °C) compared to non-heated B20. Preheating the biodiesel blend (B20) reduced the viscosity and density, which might improve the spray characteristics and atomization of fuel particles at a higher fuel inlet temperature. Due to this, better evaporation occurred, and a homogenous mixture was produced, which helped enhance the combustion reaction, resulting in better performance, better fuel combustion, and reduced emission except for NO_x compared to the non-unheated biodiesel blend (B20).