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ARTICLE

CFD-Based Simulation and Analysis of Hydrothermal Aspects in Solar Channel Heat Exchangers with Various Designed Vortex Generators

by Mohamed Salmi^1,2, Younes Menni³, Ali J. Chamkha^4,5,*, Houari Ameur⁶, Rachid Maouedj⁷, Ahmed Youcef⁷

1 Department of Physics, University of M’sila, M’sila, 28000, Algeria
2 Laboratory of Physics and Chemistry of Materials, University of M’sila, M’sila, 28000, Algeria
3 Unit of Research on Materials and Renewable Energies, Department of Physics, Abou Bekr Belkaid University, Tlemcen, 13000, Algeria
4 Faculty of Engineering, Kuwait College of Science and Technology, Doha District, Kuwait
5 Center of Excellence in Desalination Technology, King Abdulaziz University, Jeddah, 21589, Saudi Arabia
6 Department of Technology, University Center of Naama, Naama, 45000, Algeria
7 Unit´e de Recherche en Energies Renouvelables en Milieu Saharien, URERMS, Centre de D´eveloppement des Energies Renouvelables, CDER, Adrar, 01000, Algeria

* Corresponding Author: Ali J. Chamkha. Email:

Computer Modeling in Engineering & Sciences 2021, 126(1), 147-173. https://doi.org/10.32604/cmes.2021.012839

Received 14 July 2020; Accepted 09 September 2020; Issue published 22 December 2020

Abstract

The hydrothermal behavior of air inside a solar channel heat exchanger equipped with various shaped ribs is analyzed numerically. The bottom wall of the exchanger is kept adiabatic, while a constant value of the temperature is set at the upper wall. The duct is equipped with a flat rectangular fin on the upper wall and an upstream V-shaped baffle on the lower wall. Furthermore, five hot wall-attached rib shapes are considered: trapezoidal, square, triangular pointing upstream (type I), triangular pointing downstream (type II), and equilateral-triangular (type III) cross sections. Effects of the flow rates are also inspected for various Reynolds numbers in the turbulent regime (1.2 × 10⁴–3.2 × 10⁴). The highest performance (η) value is given for the II-triangular rib case in all Re values, while the square-shaped ribs show a significant decrease in the η along the achieved Re range. The η value at Remax is 2.567 for the II-triangular roughness case. Compared with the other simulated cases, this performance is decreased by about 3.768% in the case of I-triangular ribs, 15.249% in the case of III-triangular ribs, 20.802% in the case of trapezoidal ribs, while 27.541% in the case of square ribs, at the same Re_max. Also, a comparison is made with air-heat exchangers that have non-rough walls and contain cross-shaped VGs presented previously, in order to highlight the effectiveness of the rough surface presence in the baffled and finned channels. The obtained results indicated that the triangular-shaped rib (type II) has the most significant hydrothermal behavior than the other cases. This indicates the necessity of roughness heat transfer surfaces for finned and baffled channels to improve significantly the performance of the air-heat exchangers they contain.

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