Natural convection in a finned concentric annulus filled with air is numerically simulated, using the centered finite difference method if the alternating direction implicit scheme is taken into account. Two isothermal blocks are attached to the inner cylinder and placed symmetrically in the low section of the annulus. The radius ratio, as well as the dimensionless width and height of the blocks, are kept constant. The effect of the Rayleigh number Ra varying between 1000 and 10,000 on the flow pattern and heat transfer rate is discussed. It is shown that unicellular and bicellular flows are observed, and the blocks increase the overall heat transfer rate for the studied range of Ra.
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References
A. A. Berkengeim, Experimental investigation of heat transfer by natural convection in an enclosure, J. Eng. Phys., 15, No. 6, 1264–1266 (1972).
Yu. E. Karyakin, Transient natural convection in prismatic enclosures of arbitrary cross section, Int. J. Heat Mass Transf., 32, No. 6, 1095–1103 (1989).
H. R. Nagendra, M. A. Tirunarayanan, and A. Ramachandran, Free convection heat transfer in vertical annuli, Chem. Eng. Sci., 25, No. 4, 605–610 (1970).
J. P. Caltagirone, Heat transfer by natural convection in a porous layer bounded by two coaxial horizontal cylinders, Int. J. Refrig., 1, No. 1, 27–32 (1978).
B. Chandra Shekar, P. Vasseur, L. Robillard, and T. Hung Nguyen, Natural convection in a heat generating fluid bounded by two horizontal concentric cylinders, Can. J. Chem. Eng., 62, No. 4, 482–489 (1984).
M. Al-Arabi, M. A. I. El-Shaarawi, and M. Khamis, Natural convection in uniformly heated vertical annuli, Int. J. Heat Mass Transf., 30, No. 7, 1381–1389 (1987).
A. Cheddadi, J. P. Caltagirone, A. Mojtabi, and K. Vafai, Free two-dimensional convective bifurcation in a horizontal annulus, ASME J. Heat Transf., 114, No. 1, 99–106 (1992).
K. N. Volkov and A. G. Karpenko, Computational modeling of free convection between coaxial cylinders on the basis of a preconditioned form of Navier–Stokes equations, J. Eng. Phys. Thermophys., 87, No. 4, 929–935 (2014).
N. Nagarani, K. Mayilsamy, A. Murugesan, and G. Sathesh Kumar, Review of utilization of extended surfaces in heat transfer problems, Renew. Sustain. Energy Rev., 29, 604–613 (2014).
M. Esmail and A. Mokheimer, Performance of annular fins with different profiles subject to variable heat transfer coefficient, Int. J. Heat Mass Transf., 45, No. 17, 3631–3642 (2002).
H. T. Chen and W. L. Hsu, Estimation of heat transfer coefficient on the fin of annular-finned tube heat exchangers in natural convection for various fin spacings, Int. J. Heat Mass Transf., 50, Nos. 9–10, 1750–1761 (2007).
B. Kundu and D. Barman, An analytical prediction for performance and optimization of an annular fin assembly of trapezoidal profile under dehumidifying conditions, Energy, 36, No. 5, 2572–2588 (2011).
B. Kundu and P. K. Das, Performance analysis and optimization of straight taper fins with variable heat transfer coefficient, Int. J. Heat Mass Transf., 45, No. 24, 4739–4751 (2002).
M. H. Sharqawy and S. M. Zubair, Efficiency and optimization of straight fins with combined heat and mass transfer — An analytical solution, Appl. Therm. Eng., 28, Nos. 17–18, 2279–2288 (2008).
B. Kundu, Beneficial design of unbaffled shell-and-tube heat exchangers for attachment of longitudinal fins with trapezoidal profile, Case Studies Therm. Eng., 5, 104–112 (2015).
J. C. Chai and S. V. Patankar, Laminar natural convection in internally finned horizontal annuli, Numer. Heat Transf., 24, No. 1, 67–87 (1993).
M. Farinas, A. Garon, and K. Saint-Louis, Study of heat transfer in a horizontal cylinder with fins, Rev. Gén. Therm., 36, No. 5, 398–410 (1997).
M. Rahnama and M. Farhadi, Effect of radial fins on two-dimensional turbulent natural convection in a horizontal annulus, Int. J. Therm. Sci., 43, No. 3, 255–264 (2004).
A. Idrissi, A. Cheddadi, and M. T. Ouazzani, Heat transfer in an annular space fitted with heating isothermal blocks: Numerical bifurcation for low blocks height, Case Studies Therm. Eng., 7, 1–7 (2015).
G. A. Sheikhzadeh, M. Arbaban, and M. A. Mehrabian, Laminar natural convection of Cu–water nanofluid in concentric annuli with radial fins attached to the inner cylinder, Int. J. Heat Mass Transf., 49, No. 3, 391–403 (2013).
Y. R. Li, X. F. Yuan, Y. P. Hu, and J. W. Tang, Experimental research on natural convective heat transfer of water near its density maximum in a horizontal annulus, Exp. Therm. Fluid Sci., 44, 544–549 (2013).
Y. Taher, A. Cheddadi, and M. T. Ouazzani, Heat transfer in an annular space provided with fins: Numerical simulation of the effect of the fins width, Phys. Chem. News, 30, 132–138 (2006).
D. Angeli, G. S. Barozzi, M. W. Collins, and O. M. Kamiyo, A critical review of buoyancy-induced flow transitions in horizontal annuli, Int. J. Therm. Sci., 49, No. 12, 2231–2241 (2010).
T. H. Kuehn and R. J. Goldstein, An experimental and theoretical study of natural convection in the annulus between horizontal concentric cylinders, J. Fluid Mech., 74, No. 4, 695–719 (1976).
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Published in Inzhenerno-Fizicheskii Zhurnal, Vol. 92, No. 4, pp. 1099–1105, July–August, 2019.
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Touzani, S., Idrissi, A., Cheddadi, A. et al. Numerical Study of Laminar Natural Convection in a Finned Annulus: Low Isothermal Blocks Positions. J Eng Phys Thermophy 92, 1064–1071 (2019). https://doi.org/10.1007/s10891-019-02021-6
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DOI: https://doi.org/10.1007/s10891-019-02021-6