Thermodynamic and sustainability assessment of real-time non-surfactant crude palm oil emulsion fuel in a compression ignition engine

Biodiesel fueled diesel engines are a viable alternative to conventional diesel systems, but the inherently lower calorific value of biodiesel increases the fuel demand for achieving the same power output. Water-in-fuel emulsions can partly offset this drawback by promoting micro-explosion driven by secondary atomization, which enhances fuel air mixing and improve combustion. This study presents an experimental energy, exergy, entropy (3E), and sustainability assessment of a compression ignition engine operated with a real-time non-surfactant emulsion fuel supply system (RTES) using crude palm oil water emulsion. The in house RTES eliminates the need for chemical surfactants and delivers emulsion fuel in real time, preventing phase separation and enabling more effective secondary atomization. Results show that the total fuel energy and exergy requirement decreased for emulsion fuel by 7.7% and 5.6%, respectively, while energy efficiency and exergy efficiency improved by 8.4% and 5.3%, respectively. Due to the cooling effect offered by the water emulsion reduced, exhaust energy losses by about 39.4%. Entropy generation decreased by 8%, indicating a shift toward more ideal thermodynamic behavior. Sustainability index analysis confirms that crude palm oil exhibits improved sustainability when supplied as a water-in-fuel emulsion.