Abstract
The widespread use of biofuel-based power generation technologies is expected to not only reduce CO2 emissions but also help electrify developing countries. CO2-expanded hexane is the preferred extractant for isolating oil with a low phosphorus concentration at a high yield, and the optimal extraction conditions have been determined (temperature = 25 °C; pressure = 5.1 MPa; CO2 mole fraction = 0.87; and CO2-expanded hexane per gram of rice bran = 0.2 moles). Combustion tests were conducted using a commercially available diesel engine to evaluate the feasibility of using rice bran oil extracted under these ideal conditions. Although the engine operated at a speed of 3200 rpm within a torque range of 2–6 Nm, the output exhibited significant instability, and the thermal efficiency was ~15 % lower than that when operating on an ideal light oil. This discrepancy is attributed to the notably high total contamination (546 mg∙kg-1), substantial acid value (17.7 mgKOH∙g-1), and pronounced water concentration (673 mg∙kg-1). Engine performance can be enhanced through purification processes such as dewaxing, deacidification, and dehydration. Low-cost and simple oil extraction technologies are expected to help promote electrification in developing nations.
