Improvement of the performance of solar channels by using vortex generators and hydrogen fluid
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Improvement of the performance of solar channels by using vortex generators and hydrogen fluid Younes Menni1 · Houari Ameur2 · Mustafa Inc3,4 Received: 1 May 2020 / Accepted: 10 September 2020 © Akadémiai Kiadó, Budapest, Hungary 2020
Abstract An attempt is made to enhance the thermal hydrodynamic performance of a solar channel by using vortex generators including attached fins and detached bars. Hydrogen gas is used as a working fluid under turbulent flow conditions. The computational fluid dynamics method is used to achieve the investigations. Governing equations among fluid and solid sections are determined and solved by the computational finite volume method. The hydrodynamic characteristics, dynamic pressure, turbulent kinetic energy, turbulent viscosity, Nusselt number, skin friction, and the thermal enhancement factor (TEF) are investigated for a range of Reynolds number (Re) from 5000 to 20,000. The obtained results revealed that the TEF values are important (TEF > 1) for all Re values under investigation. The TEF values are between 1.2 and 3.5. An increase in the TEF values was observed with increased Reynolds number, where the maximum value of TEF of about 3.5 was achieved at Re = 20,000. At this value of Re, the normalized heat transfer value (Nu/Nu0) is the highest, while the normalized friction values (f/f0) are the lowest. This demonstrates the usefulness of the suggested vortex generators combined with the fluid (H2) for the successful thermal and dynamic performance within the smooth channels. Keywords Solar channel collectors · Solar heat exchangers · Forced-convection · Vortex generators · Attached fins and detached bars List of symbols C1ε Constant in k − ε model C2ε Constant in k − ε model C3ε Constant in k − ε model Cf Local coefficient of friction Cp Specific heat (J kg−1 K−1) Dh Hydraulic diameter of the exchanger (m) * Mustafa Inc [email protected] Younes Menni [email protected] Houari Ameur ameur@cuniv‑naama.dz 1
Unit of Research on Materials and Renewable Energies, Department of Physics, Faculty of Sciences, Abou Bekr Belkaid University, P.O. Box 119, 13000 Tlemcen, Algeria
2
Department of Technology, University Centre of Naama - Salhi Ahmed, P.O. Box 66, 45000 Naama, Algeria
3
Department of Mathematics, Science Faculty, Firat University, Elazig, Turkey
4
Department of Medical Research, China Medical University Hospital, China Medical University, Taichung, Taiwan
e1 Fin-bar space (m) e2 Exchanger wall-bar (m) f Average coefficient of friction f0 Factor of friction for smooth exchanger Gk Rate of production for k H Height of exchanger (m) h1 Height of attached fin (m) h2 Height of detached bar (m) k Kinetic energy of turbulence (m2 s−2) L Length of exchanger (m) L1 Inlet-1st obstacle space (m) L2 Space between obstacles (m) L3 Second Obstacle-exit space (m) Nu Average number of Nusselt Nu0 Nusselt number for the smooth exchanger Nux Local number of Nusselt P Pressure (Pa) Pd Dynamic pressure (Pa) Pr Number of Prandtl Re Number of Re
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