Using design of experiment via the linear model of analysis of variance to predict the thermal conductivity of Al2O3/ethylene glycol-water hybrid nanofluid

Abstract

In this paper, the thermal conductivity (k_nf) of the Al₂O₃/Ethylene Glycol -Water nanofluid is measured. MATLAB software is used to fit a nonlinear function, and the analysis of variance (ANOVA) is implemented to determine the effect of temperature and volume fraction of nanoparticles (φ) on extracting the residuals and k_nf. In the experimental part, various combinations of temperatures (from 30 to 60 °C) and volume fractions (fromφ = 0.15 up to 1.3%) are examined, and then the obtained data are analyzed using MINITAB software. The results show that the k_nf is highly dependent on φ and less dependent on temperature. By changing the φ from 0.15 to 1.3%, the thermal conductivity increases around 40%. In contrast, increasing the temperature from 30 to 60 °C will increase the k_nf by almost 10%. Also, the results show that the thermal conductivity slope is lower at φ < 0.75%, and this rate increases drastically for higher volume fractions. The obtained results, especially the fitting function, are useful for designing and optimizing systems using nanofluids as a working fluid in heat exchangers or energy systems.