Convection Heat Transfer, Entropy Generation Analysis and Thermodynamic Optimization of Nanofluid Flow in Spiral Coil Tube

Abstract

In this study, heat transfer, flow characteristics, and entropy generation of turbulent TiO₂/water nanofluid flow in the spiral coil tube were analytically investigated considering the nanoparticle volume fraction, curvature ratio, flow rate and inlet temperature between 0.01–0.05 percent, 0.03–0.06, 1.3–3.3 l/min, and 15–27 °C, respectively. Results showed that the augmentation of the nanoparticle volume fraction increased the Nusselt number and friction factor up to 11.9% and 1.1%, respectively, while it reduced the entropy generation number up to 10.9%. Reducing the curvature ratio led to a maximum of 11.1% increase in the Nusselt number, while it resulted in a 5.6% increase in the entropy generation number. A decline in the inlet temperature from 21 °C to 15 °C proceeded a 28.4% and 7.1% increase in the heat transfer and pressure drop, respectively. The total entropy generation reduced with increasing nanoparticle volume fraction. For a low Reynolds number, a decrease in the curvature ratio led to a reduction in the total entropy generation, while reducing the curvature ratio was detrimental for a high Reynolds number. Analytical relations for optimum curvature ratio and optimum Reynolds number were derived. For the range of parameters studied in this paper, a range of optimum Reynolds number from 9000 to 12,000 was proposed.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Notes on contributors

Mohammadreza Kadivar

Mohammadreza Kadivar received his M.Sc. degree in Mechanical Engineering from Shiraz University, Iran. He is a member of I-Form, Advanced Manufacturing Research Center and also Center for Precision Engineering, Material & Manufacturing Research at the Institute of Technology Sligo, Ireland. He is interested in heat transfer, boiling, computational fluid dynamics, thermal energy storage, and nanofluids. His specific expertise is employing computational, theoretical, and experimental methods to perform research that specifically targets the critical need for improved energy efficiency, storage, transport, and conversion.

Mohsen Sharifpur

Mohsen Sharifpur is an associate professor in the Department of Mechanical and Aeronautical Engineering at the University of Pretoria (UP), South Africa. His research area includes mathematical modeling, improvement of heat transfer by nanofluids, convective multiphase flow, computational fluid dynamics, and fluid dynamics from nanoscale to universe scale. He established a Nanofluid Research Laboratory at UP in 2010, which is one of the most active and productive nanofluids research laboratories in Africa. He is an innovative thinker and based on fluid dynamics, constructal law, nature and patterns in nature, and cosmology data; he invented a new general and multidiscipline theory as “Source and Sink Theory” (https://dx.doi.org/10.22606/tp.2020.51001). His general-multidiscipline theory has the potential to describe the early universe better than previous theories. He believes, his theory is the case of the future. He has authored or coauthored more than 130 peer-reviewed articles and international conference papers.

Josua P. Meyer

Josua Meyer is a professor, Chair of the School of Engineering and Head of the Department of Mechanical and Aeronautical Engineering at the University of Pretoria, South Africa. He specializes in heat transfer, fluid mechanics and thermodynamic aspects of heating, ventilation, and air-conditioning. He is the author and coauthor of more than 800 articles, conference papers and patents, and has received various prestigious awards for his research. He is also a fellow or member of various professional institutes and societies and is regularly invited as keynote speaker at international conferences. He is the recipient of various teaching awards. He is on the editorial board and/or (lead) editor of 15 journals (including an associate editor of Heat Transfer Engineering) and was a member of the scientific committees of more than 40 international conferences, and conference chair of more than 14 international conferences.