what is the mathematical equation to calculate a viscosity index

The study fills an important gap in empirical research in the context of the reliability of measurement results obtained using various research techniques.Įngine oil ensures smooth engine operation through its lubricating and cooling effects yet, with time and use, it becomes subject to degradation processes.

Therefore, a very careful approach is suggested when choosing these instruments. It was also found that the results obtained with the use of the mid-FTIR spectrophotometer were burdened with a very large measurement error. Consistent outcomes were obtained for the Stabinger viscometer only, whereas the microchannel viscometer and the mid-FTIR spectrophotometer were not as precise as the reference method. The main data analysis tools used in the study were multiple regression, Mahala Nobis distance, post-hoc analysis, and the Wilcoxon signed-rank test with the Bonferroni correction. The study material comprised 42 fresh engine oils, all of which are commercially available. The following instruments were selected to measure: a mid-FTIR spectrophotometer, a microchannel viscometer, and a Stabinger viscometer. Simple formulas of two constant were proposed to describe the effect of temperature on dynamic viscosity.The aim of this paper is to compare the results of kinematic viscosity of lubricating oils measurements at 40 ☌, obtained with three different rapid evaluation devices, and the standardized method using an Ubbelohde Capillary viscometer. Specialty literature suggests two, three and multi-constant formula to describe this temperature dependence. The effect of temperature on dynamic viscosity of vegetable oil has been studied by several studies. And, even accepting their weaknesses (oxidation stability, low values for viscosity at high temperature, narrower temperature ranges for applications), vegetable oil-based lubricants are being actively demanded for many green industrial activities. Introduction Vegetable oils could be substitutes for petroleum-based oils they have excellent lubricating properties such as high viscosity index, high lubricity and low volatility but also eco-friendly, renewable and less toxic. Plotting the dynamic viscosity depending on temperature shows an exponential decline. Coconut oil dynamic viscosity decreases with increasing temperature at constant shear rate. Equation constants η0, A1 and t1 were determined by fitting exponential. The purpose of this study was to find an exponential dependence between temperature and dynamic viscosity of coconut oil, using one equation.

This article proposes new rheological models for coconut oil.

What is the mathematical equation to calculate a viscosity index