Study on Mixed Convection Heat Transfer in Vertical Ducts with Radiation Effects

Authors: G. Rajamohan, N. Ramesh, P. Kumar

Abstract:

Experiments have been performed to investigate the radiation effects on mixed convection heat transfer for thermally developing airflow in vertical ducts with two differentially heated isothermal walls and two adiabatic walls. The investigation covers the Reynolds number Re = 800 to Re = 2900, heat flux varied from 256 W/m2 to 863 W/m2, hot wall temperature ranges from 27°C to 100 °C, aspect ratios 1 & 0.5 and the emissivity of internal walls are 0.05 and 0.85. In the present study, combined flow visualization was conducted to observe the flow patterns. The effect of surface temperature along the walls was studied to investigate the local Nusselt number variation within the duct. The result shows that flow condition and radiation significantly affect the total Nusselt number and tends to reduce the buoyancy condition.

Keywords: Mixed convection, vertical duct, thermally developing and radiation effects.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1062770

References:

[1] J.D.Jackson, M.A.Cotton, and B.P.Axcell, "Studies of mixed convection in vertical tubes," International Journal of Heat and Fluid Flow, vol. 10, pp.1-15, July 1989.
[2] W.M.Yan, and H.Y.Li, "Radiation Effects on Mixed convection heat transfer in a vertical square ducts," International Journal of Heat and Mass Transfer, vol. 44, pp.1401-1410, Apr. 2001.
[3] T.T.Chandratilleke, N.Ramesh, and P.Wangdham-koom, "Convective heat transfer in airflow through a duct with thermal radiation," IOP Conference Series 10 Materials Science and Engineering, 012026, Jan. 2010.
[4] G.Rajamohan, N.Ramesh, G.Alexander, and P.Kumar, "Experimental study on mixed convection heat transfer for thermally developing flow in horizontal ducts with radiation effects," ASME/JSME 8th Thermal Engineering Joint Conference, 44174, Mar. 2011.
[5] A.Barletta, E.Rossi di Schio, and E.Zanchini, "Combined forced and free flow in a vertical rectangular duct with prescribed wall heat flux," International Journal of Heat and Fluid Flow, vol. 24, pp. 874-887, July 2003.
[6] A. Barletta, E.Magyari, and B.Keller, "Combined forced and free flow in a vertical rectangular duct with prescribed wall heat flux," International Journal of Heat and Mass transfer, vol. 24, pp. 874-887, Aug. 2005.
[7] C.Gau, Y.C.Jeng, and C.G.Liu, "An experimental study on mixed convection in a horizontal rectangular channel heated from a side," Transactions of the ASME Journal of Heat Transfer, vol. 122, pp. 701- 707, Nov.2000.
[8] C.S.Yang, C.G.Liu, and C.Gau, "Study of channel divergence on the flow and heat transfer in horizontal ducts heated from a side," International Journal of Thermal Sciences, vol. 48, pp.105-113, Feb.2009.
[9] J.R.Maughan, and F.P.Incropera, "Experiments on mixed convection heat transfer for airflow in a horizontal and inclined channel," International Journal of Heat and Mass Transfer, vol.30, pp.1307-1318, Nov.1987.
[10] J.R.Maughan, and F.P.Incropera, "Regions of heat transfer enhancement for laminar mixed convection in a parallel plate channel," International Journal of Heat and Mass Transfer, vol. 33(3), pp.555-570, Nov.1990.
[11] N.Ramesh, and S.P.Venkateshan, "Experimental study of natural convection in a square enclosure using differential interferometer," International Journal of Heat and Mass Transfer, vol. 44(6), pp.1107- 1117, May 2001.
[12] M.Y.Chang, and T.F. Lin, "Experimental study of aspect ratio effects on longitudinal vortex flow in mixed convection of air in a horizontal rectangular duct," International Journal of Heat and Mass Transfer, vol. 41, pp.719-733, May 1997.
[13] A.Dogan, M.Sivrioglu, and S.Baskaya, "Experimental investigation of mixed convection heat transfer in a rectangular channel with discrete heat sources at the top and at the bottom," International Communications in Heat and Mass Transfer, vol. 32, pp.1244-1252, July 2005.
[14] H.W.Coleman, and W.G.Steele Jr, "Experimentation and Uncertainty Analysis for Engineers," 2nd ed., John Wiley & Sons, New York 275, Mar.1989.