Influence of Laser Light on Specific Physical and Chemical Characteristics of Diesel Fuel

This study investigates the potential of laser light as a non-chemical method to modify the molecular structure of diesel fuel, with the objective of enhancing key performance properties such as viscosity, density, and Cetane number (CN). Sudanese diesel fuel sourced from the Khartoum refinery was analyzed before and after laser exposure to evaluate the extent of property enhancement. Using a calibrated viscometer and ASTM standard procedures, the kinematic viscosity and density were measured, while CN was determined using the bracketing hand wheel method with a test engine and reference fuels. A 10 mL sample of diesel was irradiated with laser light for 60 minutes under controlled laboratory conditions at the Central Petroleum Laboratories in Khartoum. Post-exposure results revealed a significant reduction in kinematic viscosity (from 3.571 mm²/s to 1.40 mm²/s) and density (from 0.927 g/cm³ to 0.78 g/cm³), alongside an increase in CN from 57.2 to 62.4. These enhancements suggest molecular restructuring—primarily the transformation of cyclic and branched hydrocarbons into linear chains—resulting in improved combustion characteristics. The findings demonstrate the feasibility of laser-based treatment as a novel technique for refining diesel fuel quality.