Experimental and theoretical assessment of surface tension using different biodiesels at elevated temperature

The rheological property of biodiesel is determined by the methods of production, which constitute an important role in atomization, combustion, performance, and emission. Surface tension has a major contribution to droplet size in atomization characteristics. Therefore, it is necessary to examine the surface tension to enhance atomization. The surface tension of six biodiesels, Karanja, jatropha, soybean, palm, sunflower, and rapeseed oil, was measured experimentally and compared with three mathematical models, including the MacLeod–Sugden model, the Gibbs free energy model, and the Dalton type mass average model using MATLAB software. One more parameter was added to the Gibbs free model, which showed results that were more similar to experimental results. The proposed models use the temperature range of 300 to 360 K on changes in biodiesel properties. The study showed that the Gibbs free energy model exhibited a 1.6% to 6.8% error, the MacLeod–Sugden model 3.2% to 12.1%, and the Dalton type mass average model 9.52% to 14.16% with experimentation.