Comparative CFD Analysis of Cylindrical, Oval, and Finned Tubes for Thermosiphons

International Journal of Civil Engineering

© 2026 by SSRG - IJCE Journal

Volume 13 Issue 1

Year of Publication : 2026

Authors : Heydi Karina Hinostroza Maravi, Nelfa Estrella Ayuque Almidon, Aron Jhonatan Aliaga Contreras, Jean Fernando Perez Montesinos

10.14445/23488352/IJCE-V13I1P111

How to Cite?

Heydi Karina Hinostroza Maravi, Nelfa Estrella Ayuque Almidon, Aron Jhonatan Aliaga Contreras, Jean Fernando Perez Montesinos, "Comparative CFD Analysis of Cylindrical, Oval, and Finned Tubes for Thermosiphons," SSRG International Journal of Civil Engineering, vol. 13,  no. 1, pp. 132-139, 2026. Crossref, https://doi.org/10.14445/23488352/IJCE-V13I1P111

Abstract:

The purpose of the present study is to evaluate the geometric impact on the thermal performance of solar thermosiphon tubes through the use of parametric modeling and CFD simulation. To achieve this purpose, three configurations were designed: cylindrical, oval, and with longitudinal fins, and the constant internal volume was maintained to ensure comparable conditions. The models in this paper were developed in the Autodesk Inventor software and then integrated into Autodesk CFD in conditions of average solar irradiance (850 W/m²) and laminar internal flow. The key variables of these results, such as maximum temperature, total heat flow, pressure drop, and internal thermal distribution, were analyzed. The outcomes of the performed analysis show that the finned model is the one with the highest thermal efficiency due to the increased exchange surface area, while the oval design presents an offer with a more homogeneous distribution that does not affect hydraulic behavior significantly. In addition, the cylindrical configuration, although less thermally efficient, permits maintaining a more stable flow profile, and this feature is relevant in passive, pump-less applications. This work presents a technical alternative for residential buildings that has the characteristic of being a low-cost and replicable one, and this viable option combines structural design, thermal analysis, and architectural functionality in areas with a high rate of solar radiation.

Keywords:

CFD simulation, Thermosiphon systems, Absorber tube design, Solar thermal performance, Parametric modeling.

References:

[1] Global Energy and Climate Model: Scenario Analysis of Future Energy Trends, International Energy Agency, 2025. [Online]. Available: https://www.iea.org/reports/global-energy-and-climate-model
[2] Tanveer Ahmad, and Dongdong Zhang, “A Critical Review of Comparative Global Historical Energy Consumption and Future Demand: The Story Told So Far,” Energy Reports, vol. 6, pp. 1973-1991, 2020.
[CrossRef] [Google Scholar] [Publisher Link]
[3] A. Jamar et al., “A Review of Water Heating System for Solar Energy Applications,” International Communications in Heat and Mass Transfer, vol. 76, pp. 178-187, 2016.
[CrossRef] [Google Scholar] [Publisher Link]
[4] Ruslan Botpaev et al., “Drainback Solar Thermal Systems: A Review,” Solar Energy, vol. 128, pp. 41-60, 2016.
[CrossRef] [Google Scholar] [Publisher Link]
[5] C.S. Huang et al., “Experimental Observation of Natural Convection Heat Transfer Performance of a Rectangular Thermosyphon,” Energies, vol. 12, no. 9, pp. 1-12, 2019.
[CrossRef] [Google Scholar] [Publisher Link]
[6] Neeraj Mehla, and Amit Kuma, “Experimental Evaluation of used Engine Oil based Thermal Energy Storage Coupled with Novel Evacuated Tube Solar Air Collector (NETAC),” Journal of Energy Storage, vol. 39, 2021.
[CrossRef] [Google Scholar] [Publisher Link]
[7] Mengyan Cao, Xiujian Zhao, and Xiao Gong, “Achieving High-Efficiency Large-Area Luminescent Solar Concentrators,” JACS Au, vol. 3, no. 1, pp. 25-35, 2023.
[CrossRef] [Google Scholar] [Publisher Link]
[8] Lemi Negera Woyessa et al., “Design and CFD Simulation of Solar Water Heater used in Solar Assisted Biogas System,” International Journal of Innovative Technology and Exploring Engineering (IJITEE), vol. 9, no. 3, pp. 371-380, 2020.
[CrossRef] [Google Scholar] [Publisher Link]
[9] Monaem Elmnifi et al., “Computational Fluid Dynamics Analysis of a Parabolic Trough Solar Collector for Enhanced Efficiency and Thermal Performance,” Mathematical Modelling of Engineering Problems (MMEP), vol. 10, no. 3, pp. 1039-1046, 2023.
[CrossRef] [Google Scholar] [Publisher Link]
[10] Behzad Shaker et al., “CFD Analysis of Al2O3-Syltherm Oil Nanofluid on Parabolic Trough Solar Collector with a new Flange-Shaped Turbulator Model,” Theoretical and Applied Mechanics Letters, vol. 12, no. 2, pp. 1-13, 2022.
[CrossRef] [Google Scholar] [Publisher Link]
[11] Soteris A. Kalogirou, “Solar Thermal Collectors and Applications,” Progress in Energy and Combustion Science, vol. 30, no. 3, pp. 231-295, 2004.
[CrossRef] [Google Scholar] [Publisher Link]
[12] Mondher Bouteraa, and Chérif Nouar, “Rayleigh-Bénard Convection in Non-Newtonian Carreau Fluids with Arbitrary Conducting Boundaries,” International Communications in Heat and Mass Transfer, vol. 76, pp. 77-84, 2016.
[CrossRef] [Google Scholar] [Publisher Link]
[13] Lei Li, Carlos F. Lange, and Yongsheng Ma, “Association of Design and Computational Fluid Dynamics Simulation Intent in Flow Control Product Optimization,” Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture, vol. 232, no. 13, pp. 2309-2322, 2018.
[CrossRef] [Google Scholar] [Publisher Link]
[14] Dimitrios N. Korres, and Christos N. Tzivanidis, “Numerical Investigation and Optimization of an Experimentally Analyzed Solar CPC,” Energy, vol. 172, pp. 57-67, 2019.
[CrossRef] [Google Scholar] [Publisher Link]
[15] Chuan Jiang et al., “A Review of the Compound Parabolic Concentrator (CPC) with a Tubular Absorber,” Energies, vol. 13, no. 3, pp. 1-31, 2020.
[CrossRef] [Google Scholar] [Publisher Link]
[16] Javier E. Barrón-Díaz et al., “FEM-CFD Simulation and Experimental Study of Compound Parabolic Concentrator (CPC) Solar Collectors with and without Fins for Residential Applications,” Applied Sciences, vol. 11, no. 8, pp. 1-19, 2021.
[CrossRef] [Google Scholar] [Publisher Link]
[17] Yasser Abidnoor Jebbar et al., “Improvement of Heat Transfer in a Parabolic Trough Collector Receiver Tube with Hollow Cylindrical Inserts: A CFD Study,” International Journal of Heat and Technology, vol. 42, no. 3, pp. 924-932, 2024.
[CrossRef] [Google Scholar] [Publisher Link]
[18] Yinfeng Wang et al., “CFD Simulation of an Intermediate Temperature, Two-Phase Loop Thermosiphon for use as a Linear Solar Receiver,” Applied Energy, vol. 207, pp. 36-44, 2017.
[CrossRef] [Google Scholar] [Publisher Link]
[19] Gulom Uzakov, and Sokhiba Shamurotova, “CFD Analysis for Absorber Tube of a Solar Water Heater Collector,” E3S Web Conference, vol. 498, pp. 1-8, 2024.
[CrossRef] [Google Scholar] [Publisher Link]