Improvement Of Free Convection From Three horizontal Finned Cylinders Fixed Between Two Walls
Abstract
Improvement of free convection heat transfer from three finned cylinders arranged at a triangle shape fixed between two walls has been investigated in this study. Three mild steel finned cylinders fixed between two walls from Pyrex glass have been used as a test rig. It has been changed the spacing between the cylinders (X/D=1,2,3 & S/D=2,4,6) and the head orientation of a triangle to the top under constant heat flux values (38, 254, 660, 1268) W/m2 and compare with case of three finned cylinders arranged in vertical array in line fixed between two wall. The experiments are carried for Rayleigh number (Ra) from (15x103 to 14 x104 ) and Prandtl number from (0.706-0.714 ). The results indicated an increase in Nu with increasing Ra for all cylinders. Furthermore,hx and Nu increased proportionally with the increasing of cylinder spacings for all heat fluxes. Also the experimental results show the case of triangle arrangement is improvement the heat transfer more than case of vertical arrangement. Heat transfer dimensionless correlating equation is also proposed.
Nomeclature: Ax: surface area(m2), T∞: surrounding temperature(k), D: the outer diameter of fin (m), Kf: the thermal conductivity for air at film temperature(W/m.k), hx: Local convection heat transfer(W/m2.k), Gravitational acceleration(m/s2), I: Electric current (Amp), Nu: Nusselt number, Pr: Prandtl number
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[2] A.Satyanarayana.Reddy, Suresh Akella and AMK. Prasad, " Experimental Study of Free Convection Heat Transfer From Array Of Vertical Tubes At Different Inclinations", int. J. of Emerging Technology and Advanced Engineering, Vol. 4, Issue 3, March 2014.
[3] Ali Sh. Mohan, "Improvement of Heat Transfer By Free Convection From A Horizontal Fined Tube In Vertical Array Set Inside Adiabatic Duct", Master thesis, University of Technology, Iraq, 1997.
[4] Xu Xu, Zitao Yu, Yacai Hu, Liwu Fan and Kefa Cen, "A Numerical Study of Laminar Natural Convective Heat Transfer Around A Horizontal Cylinder Inside A Concentric Air-filled Triangular Enclosure" ,int. J. of Heat and Mass Transfer 53 (2010) 345-355.
[5] Arnab Kumar De and Amaresh Dalal, "A Numerical Stidy of Natural Convection Around a Sequre Horozontal Heated Cylinder Placed in An Enclosure",int. J. of Heat and Mass Transfer 49 (2006) 4608-4623.
[6] Jerod Day, "Laminar Natural Convection From Isothermal Vertical Cylinders", Master thesis, University of North Texas, U.S.A. 2012.
[7] T. Yousefi, M. Paknezhad, M. Ashjaee and S. Yazdani, "Effects of confining walls on heat transfer from a vertical array of isothermal horizontal elliptic cylinders", Experimental Thermal and Fluid Science, Vol. 33, Issue 6, September 2009.
[8] Ayla Dogan, Sinan Akkus and Senol Baskaya, "Numerical Analysis of Natural Convection Heat Transfer From Annular Fins on A Horizontal Cylinder ", J. of Thermal Science and Technology,( 2012), ISSN 1300-3615.
[9] Stig Grafsrønningen and Atle Jensen, "Natural convection heat transfer from two horizontal cylinders at high Rayleigh numbers", International Journal of Heat and Mass Transfer, Volume 55, Issues 21–22, October 2012, Pages 5552–5564.
[10] Annunziata D. Orazio and Lucia Fontana, "Experimental study of free convection from a pair of vertical arrays of horizontal cylinders at very low Rayleigh numbers" , International Journal of Heat and Mass Transfer, Volume 53, Issues 15–16, July 2010, Pages 3131–3142.
