Experimental study on the thermophysical properties, heat transfer, thermal entropy generation and exergy efficiency of turbulent flow of ZrO2-water nanofluids

The thermophysical, heat transfer coefficient, thermal entropy generation, frictional entropy generation, and exergy efficiency of ZrO2/DI-water nanofluids circulate through a tube under the turbulent flow was explored experimentally. The ZrO2 nanoparticles were developed through sol-gel technique. The thermophysical properties and heat transfer was measured in the temperature range 20-60 degrees C, volume loadings range 0.2-1.0% and Reynolds number range 2000-22000. Results shown at 1.0% vol. loading of nanofluid, thermal conductivity is increased by 24.96% at 60 degrees C; whereas the viscosity is raised by 45.57% at 20 degrees C, over base fluid. Moreover, the rise in heat transfer coefficient and Nusselt number of 1.0% vol. of nanofluid is about 46.30% and 31.65% with a friction factor penalty of 19.21% and pumping power penalty of 13.91% at a Reynolds number of 14575, against the water. Same way the thermal entropy generation is lowered by 31.65% and frictional entropy generation is raised by 19.2% at 1.0% vol. of nanofluid and at a Reynolds number of 14575. The exergy efficiency is also enhanced by 24.42% at 1.0% vol. and at a Reynolds number of 14575. Overall thermal performance factor is 1.242-times larger than water, which indicates the ZrO2 nanofluids are beneficial heat transfer fluids. (c) 2022 THE AUTHOR. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Automated summary

This experimental study investigates the thermophysical properties, heat transfer coefficient, thermal entropy generation, frictional entropy generation, and exergy efficiency of ZrO2/DI-water nanofluids circulating through a tube under turbulent flow. The results show that at a 1.0% vol. loading of nanofluid, the thermal conductivity increases by 24.96% at 60 degrees C, while the viscosity increases by 45.57% at 20 degrees C compared to the base fluid. Additionally, the heat transfer coefficient and Nusselt number of the 1.0% vol. nanofluid increase by 46.30% and 31.65% respectively, with a penalty in friction factor of 19.21% and pumping power penalty of 13.91% at a Reynolds number of 14575, compared to water. The thermal entropy generation is reduced by 31.65% and the frictional entropy generation is increased by 19.2% at the 1.0% vol. nanofluid and Reynolds number of 14575. The exergy efficiency is also enhanced by 24.42% at the 1.0% vol. and Reynolds number of 14575. Overall, the thermal performance factor of ZrO2 nanofluids is 1.242 times larger than that of water, indicating their beneficial heat transfer properties.