Fator do impacto:
FI de cinco anos:
ISSN Imprimir: 1064-2285
ISSN On-line: 2162-6561
Volume 50, 2019
Volume 49, 2018
Volume 48, 2017
Volume 47, 2016
Volume 46, 2015
Volume 45, 2014
Volume 44, 2013
Volume 43, 2012
Volume 42, 2011
Volume 41, 2010
Volume 40, 2009
Volume 39, 2008
Volume 38, 2007
Volume 37, 2006
Volume 36, 2005
Volume 35, 2004
Volume 34, 2003
Volume 33, 2002
Volume 32, 2001
Volume 31, 2000
Volume 30, 1999
Volume 29, 1998
Volume 28, 1997
Heat Transfer Research
A COMPUTATIONAL STUDY FOCUSED ON REVEALING THE RELATION BETWEEN CONVECTIVE AND RADIATIVE HEAT TRANSFER FROM A RADIANT HEATED WALL
Heat and Thermodynamics Division, Department of Mechanical Engineering, Yildiz Technical University, Yildiz,
Istanbul 34349, Turkey
Asymmetric thermal radiation is a major reason deteriorating thermal comfort in living environments being caused by wide windows, cold surfaces arising from uninsulated walls or ceilings, and the walls exposed to solar radiation. This leads different parts of a human body to face surfaces having different temperatures, and thus discrete simultaneous radiation gains or losses, which brings discomfort. In the present investigation, to simulate this thermal discomfort condition, realistic thermal boundary conditions, emissivity values, and floor dimensions are selected and applied to an enclosure. The characteristics pertaining to a heated wall, such as the proportion of radiative to convective heat transfer coefficient alongside radiative and total heat flux are examined. To achieve this purpose, a computational fluid dynamics approach for convective data, and a theoretical calculation method for the solution of radiation heat transfer within the chamber are utilized. It is revealed that as the distance between the heated wall and the opposite wall (forming a heat sink that generates an asymmetric thermal radiation) increases from 3 m to 4 m, and to 6 m, the radiative heat transfer coefficient decreases and thus the range of the ratio hr/hc also narrows from 1.10-1.70 to 1.10-1.55 due to the dwindling effects of radiation. Furthermore, three novel correlations comprising the effect of asymmetric radiation in the chamber have been derived for the ratio hr/hc radiative heat flux qr, and the total heat flux qt the deviation ranges of which remain within ± 15%, ± 10%, and ± 15%, respectively.
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Acikgoz, O., A Novel Evaluation Regarding the Influence of Surface Emissivity on Radiative and Total Heat Transfer Coefficients in Radiant Heating Systems by Means of Theoretical and Numerical Methods, Energy Buildings, vol. 102, pp. 105-116, 2015.
Acikgoz, O., Qebi, A., Dalkilic, A.S., Koca, A., Qetin, G., Gemici, Z., and Wongwises, S., A Novel ANN-Based Approach to Estimate Heat Transfer Coefficients in Radiant Wall Heating Systems, Energy Buildings, vol. 144, pp. 401-415, 2017.
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Wu, X., Olesen, B.W., Fang, L., Zhao, J., and Wang, F., Indoor Temperatures for Calculating Room Heat Loss and Heating Capacity of Radiant Heating Systems Combined with Mechanical Ventilation Systems, Energy Buildings, vol. 112, pp. 141-148, 2016.
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Zhang, D., Xia, X., and Cai, N., A Dynamic Simplified Model of Radiant Ceiling Cooling Integrated with Underfloor Ventilation System, Appl. Therm. Eng., vol. 106, pp. 415-422, 2016.
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