Evaluation of flash point and calorific value of nanostructured rapeseed oil biodiesel as an automotive fuel

Abstract

The growing need for energy and the emphasis on reducing emissions have brought attention to the importance of developing renewable energy sources, specifically biofuels. However, using vegetable oils directly in diesel engines is hindered by their high viscosity, low ability to evaporate, and high content of polyunsaturated fats. Nanoemulsions, which are created without traditional surfactants, have demonstrated remarkable thermodynamic stability. This offers a potential solution to the challenges encountered with biofuels. This paper aimed to study the system of rapeseed oil-ethanol and 1-heptanol to understand the effects these nanoemulsions have on the calorific value and flash point. Ternary fuel blends with varying amounts of ethanol, rapeseed oil, and 1-heptanol were studied at constant weight percentages of 20% 1-heptanol and 30% rapeseed oil. The calorific value was determined by using a bomb calorimeter, and the results show that increasing the amount of 1-heptanol and rapeseed oil was able to increase the calorific value of the blend and maintain it close to that of diesel fuel. The flash point was determined using the Pensky Martens Closed Cup Method according to the American Society for Testing and Materials D93 standard (ASTM Standard D93-02a, 2002), and results show that only blends at 20% and 30% 1-heptanol at a constant of 30% rapeseed oil complied with the flash point requirement for diesel. This finding highlights the potential of the tricomponent fuel being used in an internal combustion engine without modification to the engine. The improved calorific value and flash point of the blends could be attributed to the co-solvent behaviour of 1-heptanol on rapeseed oil and ethanol.