STATISTICAL ANALYSIS BY EXPERIMENTAL ERROR TREATMENT IN POWER MODELS CORRELATIONS OF PLANT OIL RHEOLOGICAL DATA AT LOW TEMPERATURES

The growing use of vegetable oils in renewable energy sources such as biodiesel justifies a better understanding of the rheological behavior of these raw materials. The analysis and statistical treatment of the dispersion of the experimental error is fundamental for a better adjustment and estimation of the parameters of the applied models. In this study, the statistical error treatment of the experimental data of rheology of four different types of vegetable oils was carried out in the correlation with power models of the Ostwald-de-Waele type. The oils studied were canola, soybean, sunflower and cotton. The applied statistical approach evaluated the influence of disregarding the experimental points with the largest deviation in the result of the correction coefficient, standard deviation and confidence interval. Improvements in statistical properties were observed with the disregard of the experimental points with the greatest deviation, especially in those oils with the worst adjustment of the model. The obtained exponents of the power model, greater than unit, show that the studied oils show dilatant rheological behavior. There is a significant variation in the exponent values for small variations in the power model adjustment, which justifies the statistical treatment of the experimental data to obtain more accurate rheological parameters.