Design-eligibility study of solar thermal helically coiled heat exchanging system with annular dimples by irreversibility concept

Cao Y. Hashemian M. Ayed H. Shawabkeh A. Issakhov A. Wae-hayee M.
January 2022 Elsevier Ltd

Renewable Energy
2022 #183 369 - 384 pp.

This is a numerical research that aims to design several helically grooved coils for solar water heating systems and compare them based on the irreversibility concept. To this end, helical coils with circle, square, horizontal elongated circle (HEC), and vertical elongated circle (VEC) cross-sections were annularly grooved for enhancing heat transfer rate. The Second law analysis in this study was performed based on several variables including flow rate (1–6 lit/min), geometrical, temperature (283–323K), and type of working fluid. Depth and distance of grooves were considered as geometrical parameters. Water, EG (CH₂OH)₂ (IUPAC name: ethane-1,2-diol), and Theminol-55 were used as heat transfer fluids. Selected fluids make a Pr range of 3.35–744. Various entropy-based indicators were used to select the most optimum condition. Moreover, the interactions between triple thermodynamic domains (energy, entropy, and exergy) were conceptualized. Results demonstrated that for all cases the highest entropy generation can be achieved in the higher flow rates (6 lit/min), also when groove depth and distance are, respectively, 1.3 mm and 20 mm. Case VEC has the lowest ratio of grooved dimensionless entropy to un-grooved dimensionless entropy.

Entropy , Exergy , Heat transfer improvement , Solar thermal

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School of Computer Science and Engineering, Xian Technological University, Xian, 710021, China
Department of Mechanical Engineering, Faculty of Engineering, Urmia University, Urmia, Iran
Department of Civil Engineering, College of Engineering, King Khalid University, Abha, 61421, Saudi Arabia
College of Engineering and Technology, American University of the Middle East, Kuwait
Department of Mathematical and Computer Modelling, al-Farabi Kazakh National University, Almaty, 50040, Kazakhstan
Department of Mechanical and Mechatronics Engineering, Faculty of Engineering, Prince of Songkla University, Hatyai, Songkhla, 90110, Thailand

School of Computer Science and Engineering
Department of Mechanical Engineering
Department of Civil Engineering
College of Engineering and Technology
Department of Mathematical and Computer Modelling
Department of Mechanical and Mechatronics Engineering

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