Forced convection analysis of mono-hybrid nanofluid flow through a 2D channel with double consecutive expansion in the presence of baffle

Articles in Press

Document Type : Full Length Research Article

Authors

1 Department of Mechanical Engineering, Tarsus University, Tarsus, 33400, Turkey

2 School of Automotive Engineering, Iran Univrsity of Science and Technology, Tehran, 16846-13114, Iran

Abstract

The fluid flow over two backward-facing steps (BFS) in series, called the double backward-facing step (DBFS), is a quintessential geometry in industrial applications. An improved mixing and heat transfer performance is often essential, and this is accomplished by applying passive flow-control methods. In this paper, the thermal-hydraulic performances of using ND/water nanofluid (NF), ZrO2/water NF, water-based rGO/ND hybrid NF (HyNf) with the temperature-dependent properties in a horizontal DBFS channel equipped with an adiabatic baffle placed vertically downward from the top wall are evaluated. The k-ω SST model in OpenFOAM is employed to solve the governing equations for the single-phase turbulent forced convection heat transfer problem.

For the pure water in the DBFS0 channel (without a baffle), as the velocity of the incoming flow raises from 0.11 to 0.2, the friction factor abates by 20%. At Re=9900, when the adiabatic baffle is installed over the first downstream wall (DBFS1), the values of 〖Nu〗_max over the first and second downstream walls enhance by 72% and 30%, respectively, compared to the BFS0 channel. Inserting an adiabatic baffle over the second heated downstream wall significantly enhances the average Nu number (by 28-31%) in contrast to the canonical case. In the DBFS1 and DBFS2 channels, the friction factor is higher than that in the canonical case by 43.24% and 304%, respectively. When the pure water is substituted with the above NFs (with ϕ=0.004 or 0.01), the value of the performance evaluation criterion (PEC) is lower than 1.0 in the turbulent separated flow. The use of an adiabatic baffle in an effective position (DBFS1) enhances the thermal efficacy of the system where a disadvantageous working fluid (with FOM1<1.0) is used. The simultaneous substitution of the base fluid in the DBFS0 channel with the single/hybrid NF in the DBFS1 or DFS2 channel is ineffective.

Keywords

Main Subjects

Journal of Heat and Mass Transfer Research

Articles in Press, Accepted Manuscript
Available Online from 27 April 2025

Files

History

  • Receive Date: 02 December 2024
  • Revise Date: 11 April 2025
  • Accept Date: 27 April 2025

Share

How to cite

Statistics