Combined Mixed Convection and Radiation Heat Transfer in the Presence of Participating Medium in a Square Cavity with an
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RESEARCH ARTICLE-CHEMICAL ENGINEERING
Combined Mixed Convection and Radiation Heat Transfer in the Presence of Participating Medium in a Square Cavity with an Inside Heated Plate N. Hamici1 · A. Sahi2 · D. Sadaoui1 Received: 19 April 2019 / Accepted: 19 March 2020 © King Fahd University of Petroleum & Minerals 2020
Abstract The present paper analyses the interaction between thermal radiation and mixed convection inside a square vented enclosure containing a thin heated plate. The cavity walls are assumed to be diffuse, grey and opaque, while the working fluid is considered to be a radiatively absorbing, emitting and scattering medium. The main attention is focused on the effect of plate inclination angle and radiative parameters on the thermal field, fluid flow and heat transfer rate. The mixed convection governing equations are discretised using the finite volume method and are solved using the SIMPLE algorithm, whereas the solution of the radiative transfer equation is obtained using the discrete ordinate method (DO). Flow parameters such as Grashof number Gr and Richardson number Ri, and geometrical parameters like heated plate inclination are varied to show their impact on heat transfer enhancements. The effect of radiation parameters namely the radiation–conduction parameter RC and fluid optical thickness τ are also discussed while the walls emissivity and single scattering albedo were kept constant. The obtained results show that there is not a limited angle which improves heat transfer for all considered cases, but for every Gr and Ri value, there is a specific inclination which gives the most efficient rate of heat transfer, regardless of other considered parameters. The findings also highlight the influence of thermal radiation on heat transfer behaviour within the enclosure. Keywords Mixed convection · Thermal radiation · Square cavity · Inclined plate · Participating fluid · Optical proprieties
List of Symbols Cp g h h I Ib Gr H k
B
Specific heat at constant pressure (J kg−1 K−1 ) Gravitational acceleration (m s−2 ) Plate length (m) Plate midsection distance to vertical left wall (m) Radiation intensity (w m−2 sr−1 ) Radiation intensity of black body (w m−2 sr−1 ) Grashof number Gr gβT H 3 /υ 2 Height (m) Thermal conductivity (W m−1 K−1 ) A. Sahi [email protected]
1
Laboratoire de Mécanique, Matériaux et Energétique (L2ME), Faculté de Technologie, Université A. Mira de Bejaia, 06000 Bejaia, Algérie
2
Laboratoire de Physique Théorique (LPT), Faculté de Technologie, Université A. Mira de Bejaia, 06000 Bejaia, Algérie
n Nu Nu p (P) Pr q r , Qr
Normal to surface unit vector Local Nusselt number Average Nusselt number Dimensional pressure (dimensionless) (Pa) Prandtl number (Pr υ/α) Dimensional net radiative flux density (dimensionless Q r qr /σ Th4 Qr qr /σ TH 4 ) (W m−2 ) r Position vector RC Radiation–conduction parameter Re Reynolds number (Re u 0 H /υ) Ri Richardson number (Ri Gr/Re2 ) Direction vector s, s S(S*) Source term (dimensionless S ∗ S/σ Th4 ) (W m−2 ) T Dime
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