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Solar ETC Type Water Heaters – An Analysis Based on CFD Packages


  • Department of Mechanical Engineering, NIT Calicut – 673601, Kerala, India
  • Department of Mechanical Engineering, VAST, Mumbai – 400059, Maharashtra, India


Objectives: A comparative numerical analysis is conducted, to emphasize the capability of an open source CFD package (OpenFOAM) over the commercial CFD package of ANSYS. Methods/Analysis: Buoyancy driven flows occurring within the vacuum tubes of gravity-assisted solar water heaters are analyzed. A scaled model of the ETC type solar water heater has been chosen for computation. The geometry and meshing of the model was done by using the 'Design Modeler' and 'ICEM-CFD' packages available in ANSYS. The same configuration was also modeled in OpenFOAM to account for 3-D, transient, incompressible, laminar fluid flow analyses analogous to the available models in FLUENT. Findings: Boussinesq approximation is considered to be valid. Governing equations were discretized based on Finite Volume Method (FVM). The significance of the inlet velocity and varying incident solar radiation on the nature of flow and performance of the collector is examined. Mass flow rates have been varied from 0.0002 to 0.03 kg/s while the solar insolation considered was in the range of 300 to 1000 W/m2. For a uniform heat flux, with decrease in velocity of the fluid entering the storage tank, temperature of the water obtained at the outlet was found to be higher. This is due to the prolonged interaction of the fluid with the tube walls, which facilitates a higher heat gain from the tube surface to the fluid. Similarly, as the heat flux increases, the magnitude of the tube surface temperature increases which results into a higher outlet temperature. The performance of ETC type solar water heaters is said to be more efficient at lower flow rates and the same is true at higher incident solar radiations. Applications/Improvements: Comparison of the results between OpenFOAM and FLUENT shows the wide reliability and urges the use of open source software like OpenFOAM for more complicated CFD modeling and computational studies.


Finite Volume, Flow Rate, Heat Flux, OpenFOAM, Solar Water Heater.

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  • Vilet GC. Natural convection local heat transfer on constantheat flux inclined surfaces. Journal of Heat Transfer. 1969 Nov; 91(4):511–6. Crossref
  • Vilet GC, Liu KC. An experimental study of turbulent natural convection boundary layers. Journal of Heat Transfer. 1969 Nov; 91(4):517–31. Crossref
  • Shitzer A, Kalmanoviz D, Zvirin Y. Grossman G. Experiments with a flat plate solar water heating system in thermosyphonic flow. Solar Energy. 1978 Aug; 22(1):27–35. Crossref
  • Celentano R, Kirchner R. An experimental study on oncethrough thermosiphon system. Transactions of ASME. 1988 May; 110(2):90–7. Crossref
  • Huang BJ. Development of long-term performance correlation for solar thermosyphon water heater. Transactions of ASME. 1989 May; 111(2):124–31. Crossref
  • Bannerot RB, Yi-Wey T, Scott A, Placke G, Poche T. A simple device for monitoring flow rates in thermosyphon solar water heaters. Journal of Solar Engineering. 1992 Feb; 114(1):47–52. Crossref
  • Shariah A, Shalabi B. Optimal design for a thermosyphon solar water heater. Renewable Energy. 1997 Jul; 11(3):351– 61. Crossref
  • Abdunnabi MJR, Loveday DL. Optimization of thermosyphon solar water heaters using TRNSYS. Part 2: Parametric study using a modified TRNSYS model. IPCBEE. 2012 Jun; 28:154–60.
  • Kalogirou SA, Papamarcou C. Modeling of a thermosyphon solar water heating system and simple model validation. Renewable Energy. 2000 Feb; 21(3-4):471–93. Crossref
  • Belessiotis V, Mathioulakis E. Analytical approach of thermosyphon solar domestic hot water system performance. Solar Energy. 2002 Apr; 72(4):307–15. Crossref
  • Bolaji BO. Flow design and collector performance of natural circulation solar water heater. Journal of Engineering and Applied Sciences. 2006 Jun; 1(1):7–13.
  • Budihardjo I, Morrison G L, Behnia M. Natural circulation flow through water-in-glass evacuated tube solar collectors. Solar Energy. 2007 Dec; 81(12):1460–72. Crossref
  • Sato AI, Scalon VL, Padilha A. Numerical analysis of a modified evacuated tubes solar collector. RE&PQJ. 2012 Apr; 1(10):384–9.
  • Mohammadkarim A, Kasaeian A, Kaabinejadian A. Performance investigation of solar evacuated tube collector using TRNSYS in Tehran. International Journal of Renewable Energy Research. 2014 May; 4(2):497–503.
  • Arun KR, Dileep K, Jayaraj S. Numerical investigation on buoyancy driven flows in a non-pressurized ETC type solar water heater used for domestic applications. 6th International National Conference on FMFP MNIT; Allahabad. 2016 Dec.


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