Nusselt-Rayleigh correlations for free convection in 2D air-filled parallelogrammic enclosures with isothermal active walls

Baı̈ri, A.; Zarco-Pernia, E.; María, Juan; Bauzin, Jean-Gabriel; Alilat, Nacim; Laraqi, Najib; Gutiérrez, Facundo

doi:10.1007/s00231-010-0750-z

Cited by 13 publications

(8 citation statements)

References 15 publications

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“…Some details concerning the transient convective heat transfer are provided in the numerical and experimental study [11]. Correlations of the Nu-Ra type for these configurations have been recently proposed by García de María et al [12], while correlations for the case of the hot wall entirely isothermal are proposed by Baïri et al [13]. Details on convective heat transfer for the case of imposed constant heat flux to the hot wall have been treated by Baïri et al [14].…”

Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Effects of viscous shear stress on thermoregulation of electronics. Transient free convection in diode enclosures induced by discrete heat bands under constant heat flux

Baı̈ri¹

2011

Applied Thermal Engineering

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Thermal and dynamic phenomena that occur in the immediate vicinity of electronic components during operation generate viscous shear stresses due to velocity gradients. When thermocouples used for thermal regulation of these assemblies are installed in this environment, temperature measurements may be erroneous. It is therefore essential to take into account viscous effects in the boundary layer when dealing with thermal control of electronics subjected to natural convection. These phenomena are particularly pronounced and complex when generation of heat at the active wall is not uniform. That is the case for the real device treated in this work. The natural convective flow is generated by a vertical wall composed by alternated adiabatic and heated bands under constant heat flux, representing a working electronic equipment. The 2D transient boundary layer near the vertical active hot wall of parallelogram-shaped enclosures is treated in order to determine the viscous shear stress. Results are obtained by numerical approach using the finite volume method. Many geometrical configurations are treated while varying the inclination angle of the top and bottom passive adiabatic walls. The very different local distributions of viscous shear stresses and vertical thermal gradients confirm the necessity to take them into account to properly install the sensors used for thermoregulation.

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Section: A C C E P T E D Accepted Manuscriptmentioning

confidence: 99%

Effects of viscous shear stress on thermoregulation of electronics. Transient free convection in diode enclosures induced by discrete heat bands under constant heat flux

Baı̈ri¹

2011

Applied Thermal Engineering

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“…The cavities with square or rectangular sections have been widely studied owing to their easy implementation. The parallelogrammic section has been treated numerically and experimentally for different thermal configurations by Abu-Nada (2015), Öztop et al (2012a), Baïri et al (2012), Baïri et al (2011) and Bhowmilk and Tou (2005). Other geometric cavities dealing with different boundaries conditions were studied by Baïri (2003) as cylindrical shape, trapezoidal by Basak et al (2009) or triangular shape by Öztop et al (2012b).…”

Section: Introductionmentioning

confidence: 99%

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

Alilat

2017

HFF

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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.

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“…Recently, the case of isothermal hot wall to on-board electronics has also been studied both numerically and experimentally by Baïri et al (2010). Moreover, correlations of the Nu - Ra type for the case of discrete heat sources have been proposed by García de María et al (2010), while correlations for the case of the hot wall entirely isothermal were proposed by Baïri et al (2011). The above numerical analyses (Baïri, 2008; Baïri et al , 2008, 2010, 2011; García de María et al , 2010) were complemented by experimental measurements that validate the used model and allowed the correct sizing of the airborne electronic circuits.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, correlations of the Nu - Ra type for the case of discrete heat sources have been proposed by García de María et al (2010), while correlations for the case of the hot wall entirely isothermal were proposed by Baïri et al (2011). The above numerical analyses (Baïri, 2008; Baïri et al , 2008, 2010, 2011; García de María et al , 2010) were complemented by experimental measurements that validate the used model and allowed the correct sizing of the airborne electronic circuits. The investigation of heat transfer and fluid flow by mixed convection in a vertical rectangular cavity containing adiabatic partitions attached to the heated wall was numerically studied by Kasbioui et al (2003).…”

Section: Introductionmentioning

confidence: 99%

3D natural convection on a horizontal and vertical thermally active plate in a closed cubical cavity

Purusothaman

Baı̈ri²,

Nithyadevi

2016

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Purpose The purpose of this paper is to examine numerically the natural convection heat transfer in a cubical cavity induced by a thermally active plate. Effects of the plate size and its orientation with respect to the gravity vector on the convective heat transfer and the flow structures inside the cavity are studied and highlighted. Design/methodology/approach The numerical code is based on the finite volume method with semi-implicit method for pressure-linked equation algorithm. The convective and diffusive terms in momentum equations are handled by adopting the power law scheme. Finally, the discretized sets of algebraic equations are solved by the line-by-line tri-diagonal matrix algorithm. Findings The results show that plate orientation and size plays a significant role on heat transfer. Also, the heat transfer rate is an increasing function of Rayleigh number for both orientations of the heated plate. Depending on the thermal management of the plate and its application (as in electronics), the heat transfer rate is maximized or minimized by selecting appropriate parameters. Research limitations/implications The flow is assumed to be 3D, time-dependent, laminar and incompressible with negligible viscous dissipation and radiation. The fluid properties are assumed to be constant, except for the density in the buoyancy term that follows the Boussinesq approximation. Originality/value The present work will give some additional knowledge in designing sealed cavities encountered in some engineering applications as in aeronautics, automobile, metallurgy or electronics.

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Nusselt-Rayleigh correlations for free convection in 2D air-filled parallelogrammic enclosures with isothermal active walls

Cited by 13 publications

References 15 publications

Effects of viscous shear stress on thermoregulation of electronics. Transient free convection in diode enclosures induced by discrete heat bands under constant heat flux

Effects of viscous shear stress on thermoregulation of electronics. Transient free convection in diode enclosures induced by discrete heat bands under constant heat flux

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

3D natural convection on a horizontal and vertical thermally active plate in a closed cubical cavity

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