Numerical study of mixed convection on jet impingement cooling in a horizontal porous layer under local thermal non-equilibrium conditions

Wong, Kok Cheong; Saeid, Nawaf H.

doi:10.1016/j.ijthermalsci.2008.06.004

Cited by 53 publications

(32 citation statements)

References 30 publications

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“…Nevertheless, the flow pressure drop is also intensified [19]. Subsequently, Wong and Saeid [20,21] conducted a heat transfer optimisation on the problem of jet flow blowing on the surface of a horizontal porous insert heated from below.…”

Section: Introductionmentioning

confidence: 99%

Mixed convection and thermodynamic irreversibilities in MHD nanofluid stagnation-point flows over a cylinder embedded in porous media

Alizadeh

Karimi

Arjmandzadeh

et al. 2018

J Therm Anal Calorim

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The impingement of CuO-water nanofluid flows upon a cylinder subject to a uniform magnetic field with constant surface temperature and embedded in porous media is investigated for the first time in literature. The surface of the cylinder can feature uniform or non-uniform mass transpiration and is hotter than the incoming nanofluid flow. The gravitational effects are taken into account and the three-dimensional governing equations of mixed convection in curved porous media, under magnetohydrodynamic effects, are reduced to those solvable by a finite difference scheme. Through varying a mixed convection parameter, the situations dominated by forced, mixed and free convection are examined systematically. The numerical solutions of these equations reveal the flow velocity and temperature fields as well as the Nusselt number and induced shear stress. These are then used to calculate the rate of entropy generation within the system by viscous and heat transfer irreversibilities. The results show that Nusselt number increases with increasing the concentration of nanoparticles, while it slightly deceases through intensifying the magnetic parameter. Non-uniform transpiration is shown to strongly affect the average rate of heat transfer. Importantly, it is demonstrated that the specific mode of heat convection can majorly influence the intensity of entropy generation and that the irreversibilities are much larger under natural convection compared to those in mixed and forced convection. Calculation of Bejan number shows that this is due to more pronounced relative contribution of viscous irreversibilities when free convection effects dominate the mixed convection process.

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Section: Introductionmentioning

confidence: 99%

Mixed convection and thermodynamic irreversibilities in MHD nanofluid stagnation-point flows over a cylinder embedded in porous media

Alizadeh

Karimi

Arjmandzadeh

et al. 2018

J Therm Anal Calorim

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“…Wong and Saeid (2009a, b) considered a jet flow blowing on the surface of a horizontal porous medium heated from below and investigated the heat transfer by mixed convection. By assuming local thermal equilibrium (Wong and Saeid 2009a) and local thermal non-equilibrium (Wong and Saeid 2009b) they conducted numerical parametric studies to optimise the Nusselt number.…”

Section: Introductionmentioning

confidence: 99%

On the Hydrodynamics and Heat Convection of an Impinging External Flow Upon a Cylinder with Transpiration and Embedded in a Porous Medium

et al. 2017

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This paper extends the existing studies of heat convection by an external flow impinging upon a flat porous insert to that on a circular cylinder inside a porous medium. The surface of the cylinder is subject to constant temperature and can include uniform or non-uniform transpiration. These cylindrical configurations are introduced in the analyses of stagnation-point flows in porous media for the first time. The equations governing steady transport of momentum and thermal energy in porous media are reduced to simpler nonlinear differential equations and subsequently solved numerically. This reveals the dimensionless velocity and temperature fields of the stagnation-point flow, as well as the Nusselt number and shear stress on the surface of the cylinder. The results show that transpiration on the surface of the cylinder and Reynolds number of the external flow dominate the fluid dynamics and heat transfer problems. In particular, non-uniform transpiration is shown to significantly affect the thermal and hydrodynamic responses of the system in the circumferential direction. However, the permeability and porosity of the porous medium are found to have relatively smaller influences.

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“…Fig. 2.b shows the LTNE parameter variation versus interstitial Biot number for different values of solid to fluid thermal conductivity ratio compared with those obtained by Wong and Saeid (2009) in the same operating conditions (Fig 2.a). As seen in these figures, the agreement between the results obtained by the present numerical code and the results from the literature is satisfactory.…”

Section: Numerical Proceduresmentioning

confidence: 93%

“…Thus, Wong and Saeid (2009) investigated numerically the thermal characteristics of the jet impingement cooling with buoyancy effect in porous media in the mixed convection regime under local thermal non-equilibrium conditions. They showed that the increase in the porosity scaled thermal conductivity ratio parameter or heat transfer coefficient parameter brings the solid and fluid towards thermal equilibrium model and the mixed convection behavior is more significant for higher Rayleigh number.…”

Section: Introductionmentioning

confidence: 99%

“…A comparison will also be made between two most appropriate LTNE criteria, one based on the maximum value of the temperature difference between the solid and fluid phases (Wong and Saeid 2009;ALSumairy et al 2013) and the other on the average value of the temperature difference between the two phases across the entire channel (Khashan and AlNimr 2005;Jaballah et al 2012;Khashan et al 2006), in order to check the degree of dependence of each criterion on the LTE assumption.…”

Section: Introductionmentioning

confidence: 99%

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Comparison between Two Local Thermal Non Equilibrium Criteria in Forced Convection through a Porous Channel

Abdedou

Bouhadef

2015

JAFM

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Two criteria are used and compared to investigate the local thermal equilibrium assumption in a forced convection through a porous channel. The first criterion is based on the maximum local temperature difference between the solid and fluid phases, while the second is based on the average of the local differences between the temperature of the solid phase and the fluid phase. For this purpose, the momentum and energy equations based on the DarcyBrinkman-Forchheimer and the local thermal non equilibrium models are solved numerically using the finite volume method. The analysis focused on searching thermophysical parameters ranges which validate local thermal equilibrium hypothesis. Thus, by using the two criteria, the obtained results mainly revealed that this local thermal equilibrium assumption is verified for low thermal conductivity ratio and Reynolds number values and for high interstitial Biot number and porosity, while it is unfavorably affected by the high values of Prandtl number. However, it is also found that the parameters ranges corresponding to the local equilibrium validity depends on the selected local thermal non equilibrium criterion.

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Numerical study of mixed convection on jet impingement cooling in a horizontal porous layer under local thermal non-equilibrium conditions

Cited by 53 publications

References 30 publications

Mixed convection and thermodynamic irreversibilities in MHD nanofluid stagnation-point flows over a cylinder embedded in porous media

Mixed convection and thermodynamic irreversibilities in MHD nanofluid stagnation-point flows over a cylinder embedded in porous media

On the Hydrodynamics and Heat Convection of an Impinging External Flow Upon a Cylinder with Transpiration and Embedded in a Porous Medium

Comparison between Two Local Thermal Non Equilibrium Criteria in Forced Convection through a Porous Channel

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