Natural convection heat transfer in heated vertical tubes with internal rings
Treść / Zawartość
Experimental investigation of natural convection heat transfer in heated vertical tubes dissipating heat from the internal surface is presented. The test section is electrically heated and constant wall heat flux is maintained both circumferentially and axially. Four different test sections are taken having 45 mm internal diameter and 3.8 mm thickness. The length of the test sections are 450 mm, 550 mm, 700 mm and 850 mm. Ratios of length to diameter of the test sections are taken as 10, 12.22, 15.56, and 18.89. Wall heat fluxes are maintained at 250–3341 W/m2 . Experiments are also conducted on channels with internal rings of rectangular section placed at various distances. Thickness of the rings are taken as 4 mm, 6 mm, and 8 mm. The step size of the rings varies from 75 mm to 283.3 mm. The nondimensional ring spacing, expressed as the ratios of step size to diameter, are taken from 1.67 to 6.29 and the non-dimensional ring thickness, expressed as the ratios of ring thickness to diameter are taken from 0.089 to 0.178. The ratios of ring spacing to its thickness are taken as 9.375 to 70.82. The effects of various parameters such as length to diameter ratio, wall heat flux, ring thickness and ring spacing on local steady-state heat transfer behavior are observed. From the experimental data a correlation is developed for average Nusselt number and modified Rayleigh number. Another correlation is also developed for modified Rayleigh number and modified Reynolds number. These correlations can predict the data accurately within ±10% error.
Bibliogr. 25 poz., rys.
- Department of Mechanical Engineering, Siksha ’O’ Anusandhan University, Bhubaneswar, PIN-751030, India, firstname.lastname@example.org
- Department of Mechanical Engineering, Gandhi Institute for Technological Advancement, Bhubaneswar, Odisha, PIN-752054, India
- Department of Mechanical Engineering, Siksha ’O’ Anusandhan University, Bhubaneswar, PIN-751030, India
-  Iyi D., Hasan R.: Natural convection flow and heat transfer in an enclosure containing staggered arrangement of blockages. Procedia Engineering 105(2015), 176– 183.
-  Buonomo B., Manca O.: Transient natural convection in a vertical micro channel heated at uniform heat flux. Int. J. Thermal Sciences 56(2012), 35–47.
-  Malik S.K., Sastri, V. M. K.: Experimental investigation of natural convection heat transfer over an array of staggered discrete vertical plates. J. Energy Heat and Mass Transfer 18(1996), 127–133.
-  Huang G.J., Wong S.C., Lin C.P.: Enhancement of natural convection heat transfer from horizontal rectangular fin arrays with perforations in fin base. Int. J. Thermal Sciences 84(2014), 164–174.
-  Cheng C.Y.: Fully developed natural convection heat and mass transfer in a vertical annular porous medium with asymmetric wall temperatures and concentrations. Appl. Therm. Eng. 26(2006), 2442–2447.
-  Capobianchi M., Aziz A.: A scale analysis for natural convective flows over vertical surfaces. Int. J. Therm. Sci. 54(2012), 82–88.
-  Sparrow E. M., Bahrami P.A.: Experiments in natural convection from vertical parallel plates with either open or closed edges. J. Heat Trans-T. ASME 102(1980), 221–227.
-  Lee K.T.: Natural convection heat and mass transfer in partially heated vertical parallel plates. Int. J. Heat Mass Tran. 42(1999), 4417–4425.
-  Mobedi M., Sunden B.: Natural convection heat transfer from a thermal heat source located in a vertical plate fin. Int. Commun. Heat Mass 33(2006), 943–950.
-  Levy E. K., Eichen P.A., Cintani W.R., and Shaw R.R.: Optimum plate spacing for laminar natural convection heat transfer from parallel vertical isothermal flat plates: experimental verification. J. Heat Transfer-T ASME 97(1975), 474–476.
-  Lewandowski W.M., Radziemska E.: Heat transfer by free convection from an isothermal vertical round plate in unlimited space. Appl. Energ. 68(2001), 187–201.
-  Dey S., Chakrborty D.: Enhancement of convective cooling using oscillating fins. Int. Commun. Heat Mass 36(2009), 508–512.
-  Awasarmol U. V., Pise A. T.: An experimental investigation of natural convection heat transfer enhancement from perforated rectangular fins array at different inclinations. Exp. Therm. Fluid Sci. 68(2015), 145–154.
-  Kundu B., Wongwises S.: Decomposition analysis on convecting– radiating rectangular plate fins for variable thermal conductivity and heat transfer coefficient. J. Franklin Inst. 349(2012), 966–984.
-  Kundu B., Lee K.S.: Exact analysis for minimum shape of porous fins under convection and radiation heat exchange with surrounding. Int. J. Heat Mass Transfer 81(2015), 439–448.
-  Singh P., Patil A.K.: Experimental investigation of heat transfer enhancement through embossed fin heat sink under natural convection. Exp. Therm. Fluid Sci. 61(2015), 24–33.
-  Roul M.K., Nayak R.C.: Experimental investigation of natural convection heat transfer through heated vertical tubes. Int. J. Engineering Research and Applications 2(2012), 1088–1096.
-  Deshmukh P.A., Warkhedkar R.M.: Thermal performance of elliptical pin fin heat sink under combined natural and forced convection. Exp. Thermal Fluid Sci. 50(2013), 61–68.
-  Taler D.: Experimental determination of correlations for mean heat transfer coefficients in plate fin and tube heat exchangers. Arch. Thermodyn. 33(2012), 1–24.
-  Taler D., Taler J.: Steady-state and transient heat transfer through fins of complex geometry. Arch. Thermodyn. 35(2014), 117–133.
-  Duda P., Mazurkiewicz G.: Numerical modeling of heat and mass transfer in cylindrical ducts. Arch. Thermodyn. 31(2010), 33–43.
-  Vliet G.C.: Natural convection local heat transfer on constant-heat-flux inclined surfaces. J. Heat Transfer 91(1969), 4, 511-516.
-  Churchill S.W., Chu H.H.S.: Correlating equations for laminar and turbulent free convection from a vertical plate. Int. J. Heat Mass Transfer 18(1975), 1323–1329.
-  Holman J.P.: Heat Transfer. McGraw-Hill, Tenth Edition 2010.
-  Velmurugan P., Kalaivanan R.: Energy and exergy analysis in double-pass solar air heater. Sadhana 41(2016), 369–376.
Opracowanie rekordu w ramach umowy 509/P-DUN/2018 ze środków MNiSW przeznaczonych na działalność upowszechniającą naukę (2018).