Engine Performance of High-Acid Oil-Biodiesel through Supercritical Transesterification

Area of Science:

• Chemical Engineering
• Renewable Energy

Background:

• High-acid oil is a relatively cheaper feedstock for biodiesel production.
• High free fatty acid (FFA) content can potentially enhance supercritical methanol transesterification.
• Biodiesel offers a renewable alternative to conventional diesel fuels.

Purpose of the Study:

• To produce biodiesel from high-acid oil using supercritical methanol transesterification.
• To evaluate the engine performance characteristics of the resulting biodiesel.
• To compare the biodiesel's performance against super-low sulfur diesel (SLSD).

Main Methods:

• Biodiesel synthesis via supercritical methanol transesterification.
• Engine performance analysis using a direct-injection diesel engine and dynamometer.
• Comparative evaluation of fuel properties and combustion characteristics.

Main Results:

• Biodiesel produced from high-acid oil exhibited adequate fuel properties.
• Compared to SLSD, the biodiesel had a lower heating value and equivalence ratio.
• Higher exhaust gas temperature, brake-specific fuel consumption (bsfc), and excess air ratio were observed for the biodiesel.
• Biodiesel combustion resulted in larger carbon residue compared to SLSD.
• Higher engine speeds led to increased exhaust gas temperature and equivalence ratio, but decreased bsfc and excess air ratio for the biodiesel.

Conclusions:

• Supercritical methanol transesterification effectively converts low-cost, high-acid oil feedstocks into renewable biodiesel.
• Biodiesel derived from high-acid oil demonstrates competitive engine performance.
• This process presents a viable pathway for producing sustainable biofuels from alternative feedstocks.