scholarly journals Analytical and numerical approach to convective heat transfer through a granular target with gas cooling

2022 ◽  
Vol 171 ◽  
pp. 107196
Author(s):  
P. Cupiał ◽  
Ł. Łacny ◽  
J. Snamina
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Numerical Approach ◽  
Gas Cooling

Transient free convection within air-filled hemispherical enclosures. Nu-Ra-Fo relationships for isothermal and inclined disk with dome oriented upwards

2015 ◽  
Vol 25 (3) ◽  
pp. 629-638 ◽  
Author(s):  
Abderrahmane Baïri
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convection Heat Transfer ◽  
Numerical Approach ◽  
Content Type ◽  
Turbulent Natural Convection ◽  
Higher Temperature ◽  
Fourier Type ◽  
Volume Method

Purpose – Nusselt-Rayleigh-Fourier type correlations are proposed to quantify the temporal evolution of convective heat transfer occurring within air-filled hemispherical enclosures whose disk, initially at ambient temperature, is suddenly maintained at a higher temperature. The temperature difference imposed between this hot wall and the isothermal cold dome involves Rayleigh number varying between 104 and 2.55×1012. Depending on the application, the disk can be inclined with respect to the horizontal plane by an angle varying between 0° (horizontal disk) and 90° (vertical disk) in steps of 15°. The paper aims to discuss these issues. Design/methodology/approach – The results are obtained by means of a numerical approach based on the finite volume method. The proposed correlations linked to the steady state Nusselt-Rayleigh internships recently published, concerning the same inclination angle and Rayleigh ranges. Findings – The statistical analysis of a large number of calculations leads to reliable results covering laminar, transitional and turbulent natural convection heat transfer zones. Practical implications – The proposed relationships can be applied in several engineering fields such as nuclear technology, solar energy, security and safety electronics, building, domotics or aeronautics. Originality/value – The new relationships proposed in this paper provide important information on the evolution of convective heat transfer during the transient regime.

Improved Modeling of Turbulent Forced Convective Heat Transfer in Straight Ducts

1999 ◽  
Vol 121 (3) ◽  
pp. 712-719 ◽  
Author(s):  
M. Rokni ◽  
B. Sunden
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Low Reynolds Number ◽  
Eddy Diffusivity ◽  
Numerical Approach ◽  
Generalized Gradient ◽  
Forced Convective Heat Transfer ◽  
Low Reynolds

This investigation concerns numerical calculation of turbulent forced convective heat transfer and fluid flow in their fully developed state at low Reynolds number. The authors have developed a low Reynolds number version of the nonlinear k-ε model combined with the heat flux models of simple eddy diffusivity (SED), low Reynolds number version of generalized gradient diffusion hypothesis (GGDH), and wealth ∝ earning × time (WET) in general three-dimensional geometries. The numerical approach is based on the finite volume technique with a nonstaggered grid arrangement and the SIMPLEC algorithm. Results have been obtained with the nonlinear k-ε model, combined with the Lam-Bremhorst and the Abe-Kondoh-Nagano damping functions for low Reynolds numbers.

scholarly journals Free Convective Heat Transfer in a Closed Gap between Concentric Semi-Hemispheres

Energies ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7479
Author(s):  
Abderrahmane Baïri ◽  
Nacim Alilat ◽  
Alexander Martín-Garín ◽  
Kemi Adeyeye ◽  
José-Antonio Millán-García ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Control Method ◽  
Simple Algorithm ◽  
Numerical Approach ◽  
Volume Control ◽  
New Correlation ◽  
Rayleigh Numbers ◽  
Free Convective Heat Transfer

Free convective heat transfer in the closed gap between concentric semi-hemispheres is quantified by means of a numerical approach based on the volume control method using the SIMPLE algorithm. The average Nusselt number is determined for several configurations obtained by varying the cavity’s aspect ratio between 0.15 and 1.5, while the Rayleigh number varies within the 5.33 × 103–4.50 × 108 range. The results show that the correlations available in the literature dealing with concentric whole spheres cannot be used for the configuration treated here. The new correlation between the Nusselt and Rayleigh numbers proposed in this work can be applied in various engineering sectors, such as in the electronic packaging considered in this present work, buildings, and architecture.

Natural convective heat transfer in the air-filled interstice between inclined concentric hemispheres

2017 ◽  
Vol 27 (10) ◽  
pp. 2375-2384 ◽  
Author(s):  
Nacim Alilat
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Design Methodology ◽  
Numerical Approach ◽  
Constant Heat Flux ◽  
Horizontal Position ◽  
Content Type ◽  
Thermal Boundary Conditions ◽  
Volume Method

Purpose The main purpose of this work is to quantify the convective heat transfer occurring between two inclined and concentric hemispheres. Design/methodology/approach The inner one is an electronic assembly generating a constant heat flux during operation. The outer hemisphere is maintained isothermal at cold temperature. The interstitial space is air-filled. The base of the equipment can be inclined with respect to the horizontal plane by an angle ranging from 0° (horizontal position with dome faced upwards) to 180° (horizontal position with dome faced downwards). Findings Nusselt–Rayleigh correlations are proposed for several configurations obtained by varying the generated power and the base inclination. The large resulting Rayleigh number ranging between 2.4 × 105 and 1.7 × 107 allows using these new and original correlations in various engineering fields, such as electronics in the present work. The calculations are realized by means of a 3D numerical approach based on the finite volume method. Originality/value The geometry and the thermal boundary conditions considered in the present survey are suitable for applications in many engineering areas.

Sign in / Sign up

Export Citation Format

Share Document