Influence of coconut oil-based biodiesel-diesel blends on injection timing in mechanical-injection diesel engines = Ảnh hưởng của hỗn hợp diesel-biodiesel gốc dầu dừa đến thời điểm phun trong động cơ diesel phun nhiên liệu kiểu cơ khí

Abstract

This study investigates the influence of coconut oil-based biodiesel blends on start of injection timing (SOI) in a diesel engine equipped with a mechanically controlled fuel system. Experimental tests were conducted using a four-cylinder diesel engine, with SOI determined from high-pressure line pressure signals. Results show that increasing the biodiesel blending ratio consistently advances SOI due to the higher bulk modulus of biodiesel compared with fossil diesel. For instance, at IMEP = 0.35 MPa, SOI shifted from 14.3° before TDC (Diesel) to 14.6° (B10) and 14.7° (B30). Such shifts may significantly affect combustion characteristics and emissions, warranting careful consideration in biodiesel applications.