Micro-emulsification vs. transesterification: an investigation of the efficacy of methanol use in improving vegetable oil engine performance

Abstract

Biofuels have gained increasing prominence in recent times. Vegetable oils such as jatropha, koranja, and coconut oil have been investigated as alternatives to diesel in reciprocating engines. However, their use faces some challenges, prompting research into various methods for improving their performance. Among these, transesterification and micro-emulsification with methanol have emerged as key approaches. However, both require the use of additional materials and energy investments, which increases cost and reduces suitability. Despite this, the question of the comparative benefits of these approaches has not been thoroughly addressed. This work investigates the use of transesterification and micro-emulsification in improving coconut oil performance in a compression-ignition engine. Five fuels were tested, including diesel, biodiesel, and three methanol emulsions. Engine performance and emissions were assessed for each fuel at various engine load conditions. The additional energy requirement for both approaches was also considered. Both methods resulted in an improvement in combustion efficiency as compared to petro-diesel, but the additional energy requirement for biodiesel was higher. Micro-emulsification proved to be more energy efficient and yielded better emissions. The use of methanol in micro-emulsifications therefore has a clear advantage over its use in transesterification, for improving the performance of engines running on vegetable oils.

Keywords:

• Methanol
• vegetable oil
• transesterification
• biofuels
• blending
• emulsions

Acknowledgements

The authors of this work would like to acknowledge the support of the technical staff, Mechanical and Manufacturing Engineering Department, at the University of the West Indies. Their assistance was critical in making this work possible. We would also like to recognise Mr Peter Ransome and the laboratory staff of the Trinidad and Tobago National Petroleum Marketing Company Ltd. Their assistance was critical in determining key fuel properties and characteristics. Lastly, the authors would like to specially acknowledge the European Development Fund for funding this work, and the Ministry of Education, the Government of the Republic of Trinidad and Tobago, who served as the fund’s administrators. Without their support, this work would not have been possible. We are indeed very grateful.

Conflict of interest

No potential conflict of interest was reported by the authors.