Experimental study on thermal conductivity of SiC-ZnO/ ethylene glycol hybrid nanofluid: Proposing an optimized multivariate correlation

Abstract

BackgroundHybrid nanofluids are a new generation of nanofluids that not only improve the thermophysical properties of the base fluid but also handle many shortcomings of mono-nanofluids. MethodThis study experimentally evaluated the thermal conductivity of a new mixture of hybrid nanofluids consisting of SiC and ZnO nanoparticles in the base fluid of ethylene glycol (EG). The effects of the nanoparticle (50% SiC + 50% ZnO) volume fractions varying from 0.2% to 1.0% were studied. To evaluate the effects of the temperature on the thermal conductivity of the hybrid nanofluid, six temperatures in the range of 25–50 °C were accurately controlled. FindingsThe novelty of the present work lies in evaluating the nanoparticle size effect on the thermal conductivity coefficient of the hybrid nanofluid by analyzing the nanoparticle sizes of 20, 55, and 90 nm. The experimental findings demonstrated that the thermal conductivity enhancement was maximized to 15.91% at the highest temperature and volume fraction and the lowest nanoparticle size. Also, a new multivariate correlation was formulated as a function of the three main parameters, i.e., temperature, nanoparticle size, and volume fraction, which shows excellent accuracy in comparison to experimental data. The proposed correlation was obtained through linear regression and multivariate analysis of variance (MANOVA), with the coefficient of determination (R2) and maximum deviation being 0.99 and 1.05%, respectively. The importance of the parameters under study was found to be in the order of volume fraction > temperature > nanoparticle size. The sensitivity analysis revealed that the thermal conductivity of the hybrid nanofluid had the highest sensitivity at 50 °C, a nanoparticle diameter of 20 nm, and a volume fraction of 1%.