Performance, Combustion and Emission Analysis of a Compression Ignition Engine Fueled with Advanced Biofuel Blends

Abstract

Third-generation microalgae are considered superior to other biodiesel feedstocks. Biomass to-liquid (BTL) diesel, a renewable fuel, has emerged as a promising alternative for transportation due to its unique properties that enhance engine performance and reduce NOx emissions compared to conventional biodiesel. This study presents a numerical investigation into the effects of neat BTL diesel and four BTL diesel-microalgae biodiesel blends, prepared by mixing 20, 40, 60, and 80 vol% microalgae biodiesel into BTL diesel on the performance of a single-cylinder diesel engine. The study employs the RK multi-zone combustion model to simulate engine behavior across five injection timings (ITs) and validated against reliable experimental data. Neat BTL diesel demonstrated improved engine performance and exhaust characteristics compared to conventional diesel, except for NOx emissions. The ignition delay, combustion duration, and premixed peak heat release rate for the microalgae-BTL blends increased by 11.04–67.24%, 0.66–13.03%, and 5.25–29.87%, respectively, while peak cylinder pressure decreased by 0.72–5.26% relative to pure BTL diesel. The microalgae-BTL blends caused brake-specific fuel consumption to rise by 2.14–7.51% across all ITs. Brake thermal efficiency decreased by 0.2–1.6% for ITs between 1° and 4° CA bTDC, but increased for ITs between 7° and 13° CA bTDC with higher biodiesel content in the blends. Additionally, the microalgae blends reduced CO2, particulate matter (PM), and smoke emissions; however, the increased NOx emissions compared to neat BTL diesel. The optimum IT is identified as 4° CA bTDC for improved performance and reduced PM and smoke with an acceptable NOₓ trade-off.