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Numerical investigation of serrated fins on natural convection from concentric and eccentric annuli with different cross sections


In this paper, the effect of internal serrated fins and eccentricity on natural convection heat transfer between annular spaces with the equivalent circular, square, and triangular cross sections has been studied numerically using control volume method. The annuli’s inner and outer walls were maintained at different uniform temperatures of 373 and 327 K, respectively, and Rayleigh number ranges were 105 ≤ Ra ≤ 108. According to the results, although heat transfer coefficient was reduced between the space of fins, fins increased the total heat transfer of both inner and outer walls of annuli. The best heat transfer rate belongs to reverse triangular annulus when fins were mounted on the inner wall. As an example, heat transfer of inner wall of reverse triangular annulus was, respectively, increased about 31 and 10% at Ra = 105 and 108, when serrated fins were mounted on the inner wall. In addition, fin efficiency of inner and outer walls was decreased with the increase in Rayleigh number. Nevertheless, thermal efficiency of reverse triangular annulus was uppermost at all Rayleigh numbers compared to other ones. In addition, eccentric annuli showed better heat transfer rate than concentric ones, in which cases 3.5 and 6.7% thermal improvements have been obtained for 0.6 and 1 mm downward movement of the inner wall at Ra = 108, respectively.

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d h :

Hydraulic diameter (m)

e :


Gr :

Grashof number

K :

Thermal conductivity (W m−1 K−1)

L :

Length (m)

Nu :

Nusselt number

p :

Pressure (Pa)

Pr :

Prandtl number

Q :

Heat transfer (W)

Ra :

Rayleigh number

T :

Temperature (K)

u :

x Component of velocity (m s−1)

v :

y Component of velocity (m s−1)

α :

Thermal diffusivity

β :

Thermal expansion factor (1/K)

υ :

Kinematic viscosity (m2 s−1)

ρ :

Density (kg m−3)

μ :

Dynamic viscosity (kg m−1 s−1)

ε :

Fin efficiency

i :

Inner surface

o :

Outer surface


  1. Isfahani SNR, Sedaghat A. A hybrid micro gas turbine and solid state fuel cell power plant with hydrogen production and CO2 capture. Int J Hydrog Energy. 2016;41(22):9490–9.

    Article  CAS  Google Scholar 

  2. Kuehn TH, Goldstein RJ. An experimental and theoretical study of natural convection in the annulus between horizontal concentric cylinders. J Fluid Mech. 1976;74(4):695–719.

    Article  Google Scholar 

  3. Kuehn TH, Goldstein RJ. An experimental study of natural confection heat transfer in concentric and eccentric horizontal cylindrical annuli. J Heat Transf. 1987;100(4):635–40.

    Article  Google Scholar 

  4. Asan H. Natural convection in an annulus between two isothermal concentric square ducts. Int Commun Heat Mass Transf. 2000;27(3):367–76.

    Article  Google Scholar 

  5. Senapati JR, Dash SK, Roy S. Numerical investigation of natural convection heat transfer over annular finned horizontal cylinder. Int J Heat Mass Transf. 2016;96:330–45.

    Article  Google Scholar 

  6. Sheikhzadeh GA. Effects of radial fins on the laminar natural convection of a nanofluid in concentric annuli. Comput Therm Sci Int J. 2012;4(2):151–8.

    Article  Google Scholar 

  7. Arbaban M, Salimpour MR. Enhancement of laminar natural convective heat transfer in concentric annuli with radial fins using nanofluids. Heat Mass Transf. 2015;51:353–62.

    Article  CAS  Google Scholar 

  8. Kim HJ, An BH, Park J, Kim DK. Experimental study on natural convection heat transfer from horizontal cylinders with longitudinal plate fins. J Mech Sci Technol. 2013;27(2):593–9.

    Article  Google Scholar 

  9. Rabienataj Darzi AA, Jourabian M, Farhadi M. Melting and solidification of PCM enhanced by radial conductive fins and nanoparticles in cylindrical annulus. Energy Convers Manag. 2016;118:253–63.

    Article  CAS  Google Scholar 

  10. El-Maghlany WM, Sorour MM, Hozien O. Experimental study of natural convection in an annulus between two eccentric horizontal square ducts. Exp Therm Fluid Sci. 2015;65:65–72.

    Article  Google Scholar 

  11. Yaghoubi M, Mahdavi M. An investigation of natural convection heat transfer from a horizontal cooled finned tube. Exp Heat Transf. 2013;26(4):343–59.

    Article  Google Scholar 

  12. Syed KhS, Ishagh M, Bakhsh M. Laminar convection in the annulus of a double-pipe with triangular fins. Comput Fluids. 2011;44:43–55.

    Article  Google Scholar 

  13. Jafarimoghaddam A, Aberoumand S. On the evaluation of a finned annular tube in convective heat transfer performance in the presence of Ag/oil nanofluid for a constant thermal flux rate boundary condition. Heat Transf Asian Res. 2017;46(7):913–23.

    Article  Google Scholar 

  14. Tavakoli MR, Farzaneh M, Shadlaghani A. Numerical investigation into the effect of fins on fluid natural convection in coaxial annuli. In: Proceedings of the 4th international conference of fluid flow, heat and mass transfer. 2017.

  15. Sourtiji E, Gorji-Bandpy M, Ganji DD, Seyyedi SM. Magnetohydrodynamic buoyancy-driven heat transfer in a cylindrical–triangular annulus filled by Cu–water nano fluid using CVFEM. J Mol Liq. 2014;196:370–80.

    Article  CAS  Google Scholar 

  16. Sheikholeslami M, Sadoughi MK. Simulation of CuO–water nanofluid heat transfer enhancement in presence of melting surface. Int J Heat Mass Transf. 2018;116:909–19.

    Article  CAS  Google Scholar 

  17. Sheikholeslami M, Rokni HB. Simulation of nanofluid heat transfer in presence of magnetic field: a review. Int J Heat Mass Transf. 2017;115:1203–33.

    Article  CAS  Google Scholar 

  18. Rashidi S, Eskandarian M, Mahian O, Poncet S. Combination of nanofluid and inserts for heat transfer enhancement. J Therm Anal Calorim. 2018.

    Article  Google Scholar 

  19. Rashidi S, Javadi P, Esfahani JA. Second law of thermodynamics analysis for nanofluid turbulent flow inside a solar heater with the ribbed absorber plate. J Therm Anal Calorim. 2018.

    Article  Google Scholar 

  20. Heydari A, Ali Akbari O, Safaei MR, Derakhshani M, Alrashed AAAA, Mashayekhi R, Ahmadi Sheikh Shabani Gh, Zarringhalam M, Nguyen TK. The effect of attack angle of triangular ribs on heat transfer of nanofluids in a microchannel. J Therm Anal Calorim. 2018;131(3):2893–912.

    Article  CAS  Google Scholar 

  21. Sheremet MA, Cimpean DS, Pop I. Free convection in a partially heated wavy porous cavity filled with a nanofluid under the effects of Brownian diffusion and thermophoresis. Appl Therm Eng. 2017;113:413–8.

    Article  CAS  Google Scholar 

  22. Farzaneh M, Tavakoli MR, Salimpour MR. Effect of reverting channels on heat transfer performance of microchannels with different geometries. J Appl Fluid Mech. 2017;10(1):41–53.

    Article  Google Scholar 

  23. Incropera FP, De Witt DP, Bergman TL, Lavine AS. Fundamental of heat and mass transfer. 6th ed. New York: Wiley; 2007.

    Google Scholar 

  24. Afrand M, Sina N, Teimouri H, Mazaheri A, Safaei MR, Hemmat Esfe M, Kamali J, Toghraie D. Effect of magnetic field on free convection in inclined cylindrical annulus containing molten potassium. Int J Appl Mech. 2015.

    Article  Google Scholar 

  25. Ahmed AQ, Shian G, Kareem AK. Energy saving and indoor thermal comfort evaluation using a novel local exhaust ventilation system for office rooms. Appl Therm Eng. 2017;110:821–34.

    Article  Google Scholar 

  26. de Queiróz L, Wendell FFB, Giacaglia GEO, Grandinetti FJ, de Moura L. Numerical modelling and simulation of multi-phase flow through an industrial discharge chute. Appl Therm Eng. 2017;125:937–50.

    Article  CAS  Google Scholar 

  27. Farzaneh M, Salimpour MR, Tavakoli MR. Design of bifurcating microchannels with/without loops for cooling of square-shaped electronic components. Appl Therm Eng. 2016;108:581–95.

    Article  Google Scholar 

  28. Shadlaghani A, Tavakoli MR, Farzaneh M, Salimpour MR. Optimization of triangular fins with/without longitudinal perforate for thermal performance enhancement. J Mech Sci Technol. 2016;30(4):1903–10.

    Article  Google Scholar 

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Correspondence to Mohammad Reza Safaei.

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Shadlaghani, A., Farzaneh, M., Shahabadi, M. et al. Numerical investigation of serrated fins on natural convection from concentric and eccentric annuli with different cross sections. J Therm Anal Calorim 135, 1429–1442 (2019).

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  • Natural convection
  • Finned annuli
  • Eccentricity
  • Thermal efficiency