Entropy Generation in a Circular Tube Heat Exchanger Using Nanofluids: Effects of Different Modeling Approaches

ABSTRACT

The main goal of this paper is to compare single- and two-phase modeling approaches for forced convection flow of water/TiO₂ nanofluid. The considered geometry is a horizontal tube with constant wall heat flux boundary condition where flow regime is turbulent. A computational fluid dynamics (CFD) approach is utilized for heat transfer and flow field estimation of the single-phase and three different two-phase approaches, namely, volume of fluid, mixture, and Eulerian models. Results are presented for Reynolds numbers ranging from 9000 to 21,000, for different nanoparticle diameters ranging from 20 to 40 nm, and for values of volume fractions ranging from 0 to 4%. The obtained results show that the values of entropy generation for thermal and turbulent dissipation are very close for the single-phase and mixture models. Numerical investigation showed that the values of entropy production for pure water are identical regardless of the CFD approach; however, when the volume fraction of nanoparticles increases, differences between the models appear.

Additional information

Notes on contributors

Mohammad Mehdi Rashidi

Mohammad Mehdi Rashidi is a professor at Tongji University, Shanghai, China. His field of current research includes heat and mass transfer, thermodynamics, exergy and second-law analysis, computational fluid dynamics, nonlinear analysis, engineering mathematics, numerical and experimental investigations of nanofluid flow for increasing heat transfer, study of magneto-hydrodynamic viscous flow, and study of magnetic bead motion.

Mohammad Nasiri

Mohammad Nasiri is a master of science student at Tabriz University, Tabriz, Iran. His field of current research includes heat and mass transfer, exergy and second-law analysis, boiling, two-phase flow, slip flow, computational fluid dynamics, and numerical investigation study of turbulent flow and magneto-hydrodynamics.

Mostafa Safdari Shadloo

Mostafa Safdari Shadloo is an associate professor in CORIA Laboratory at INSA of Rouen, St. Etienne du Rouvray, France. He works with computational fluid dynamics with expertise on multiphase, multiscale, and multiphysics fluid flow systems. His current research deals with development and validation of novel coupled Lagrangian–Eulerian methods for hydrodynamics and aeronautics applications, based on a compressible (hyperbolic) solver.

Zhighang Yang

Zhigang Yang is a professor at Tongji University, Shanghai, China, where he holds a Changjiang Professorship from the Ministry of Education, and a National 1000 Plan Professorship from the Central Government of China. He has been the founding director of the Shanghai Automotive Wind Tunnel Center, Tongji University. His research field includes flow instability, turbulence modeling, computational fluid dynamics, automobile aerodynamics, automobile aerodynamic acoustics, and vehicle thermal environment management.