Mixed Convection in Vertical Flat and Circular Porous Microchannels

Авраменко, А. А.; Kovetska, Yu.Yu.; Shevchuk, Igor V.; Tyrinov, A. I.; Shevchuk, V.I.

doi:10.1007/s11242-018-1104-4

Cited by 27 publications

(5 citation statements)

References 41 publications

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“…In this case, the effect of slippage on heat transfer weakens with the increasing Prandtl number, which can be explained by a decrease in the temperature jump on the wall at large Prandtl numbers. The same trend was also observed at mixed convection in pure fluids in microchannels [17,18], as well as in porous microchannels [24].…”

Section: Heat Transfersupporting

confidence: 77%

Heat transfer and hydrodynamics of slip confusor flow under second-order boundary conditions

Авраменко

Dmitrenko

Shevchuk

2020

J Therm Anal Calorim

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The paper focused on an analytical analysis of the main features of heat transfer in incompressible steady-state flow in a microconfusor with account for the second-order slip boundary conditions. The second-order boundary conditions serve as a closure of a system of the continuity, transport, and energy differential equations. As a result, novel solutions were obtained for the velocity and temperature profiles, as well as for the friction coefficient and the Nusselt number. These solutions demonstrated that an increase in the Knudsen number leads to a decrease in the Nusselt number. It was shown that the account for the second-order terms in the boundary conditions noticeably affects the fluid flow characteristics and does not influence on the heat transfer characteristics. It was also revealed that flow slippage effects on heat transfer weaken with an increase in the Prandtl number.

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Section: Heat Transfersupporting

confidence: 77%

Heat transfer and hydrodynamics of slip confusor flow under second-order boundary conditions

Авраменко

Dmitrenko

Shevchuk

2020

J Therm Anal Calorim

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“…( 25)). Like in the previous studies (Dehghan et al 2015(Dehghan et al , 2016Avramenko et al 2018Avramenko et al , 2019, velocity and temperature jumps are governed by the value of the Knudsen number.…”

Section: Problem Statement and Governing Equationsmentioning

confidence: 54%

“…Here, the no-slip conditions on the wall are replaced by the slip conditions expressed in terms of the velocity and temperature jumps quantified using the Knudsen and Prandtl numbers. We have successfully applied these conditions in the calculations of forced and mixed convection (Avramenko et al 2018(Avramenko et al , 2019.…”

Section: Problem Statement and Governing Equationsmentioning

confidence: 99%

“…Dehghan et al (2016) extended their study to cover wide range of different parameters to suggest better designs of micro-heat exchangers to provide heat transfer enhancement at the expense of possible minimal pressure drop. Avramenko et al (2018Avramenko et al ( , 2019 modeled mixed convection in vertical flat and circular porous microchannels using the first-and second-order boundary conditions. The authors studied effects of the Knudsen and Rayleigh numbers, as well as porosity on heat transfer intensity and pressure losses in porous microchannels.…”

Section: Introductionmentioning

confidence: 99%

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Convective Instability in Slip Flow in a Vertical Circular Porous Microchannel

2021

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The paper represents an analysis of convective instability in a vertical cylindrical porous microchannel performed using the Galerkin method. The dependence of the critical Rayleigh number on the Darcy, Knudsen, and Prandtl numbers, as well as on the ratio of the thermal conductivities of the fluid and the wall, was obtained. It was shown that a decrease in permeability of the porous medium (in other words, increase in its porosity) causes an increase in flow stability. This effect is substantially nonlinear. Under the condition Da > 0.1, the effect of the porosity on the critical Rayleigh number practically vanishes. Strengthening of the slippage effects leads to an increase in the instability of the entire system. The slippage effect on the critical Rayleigh number is nonlinear. The level of nonlinearity depends on the Prandtl number. With an increase in the Prandtl number, the effect of slippage on the onset of convection weakens. With an increase in the ratio of the thermal conductivities of the fluid and the wall, the influence of the Prandtl number decreases. At high values of the Prandtl numbers (Pr > 10), its influence practically vanishes.

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“…Heat transfer during natural and mixed convection has been studied extensively. In particular, some works [18][19][20][21][22][23][24] investigated the cases of natural and mixed convection in different geometries for the different ranges of physical parameters in the frames of the ideal gas model. The cases of real gases were considered in the studies [25][26][27].…”

Section: Introductionmentioning

confidence: 99%

An Integral Method for Natural Convection of Van Der Waals Gases over a Vertical Plate

et al. 2021

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This paper focuses on a study of natural convection in a van der Waals gas over a vertical heated plate. In this paper, for the first time, an approximate analytical solution of the problem was obtained using an integral method for momentum and energy equations. A novel simplified form of the van der Waals equation for real gases enabled estimating the effects of the dimensionless van der Waals parameters on the normalized heat transfer coefficients and Nusselt numbers in an analytical form. Trends in the variation of the Nusselt number depending on the nature of the interaction between gas molecules and the wall were analyzed. The results of computations for a van der Waals gas were compared with the results for an ideal gas.

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Mixed Convection in Vertical Flat and Circular Porous Microchannels

Cited by 27 publications

References 41 publications

Heat transfer and hydrodynamics of slip confusor flow under second-order boundary conditions

Heat transfer and hydrodynamics of slip confusor flow under second-order boundary conditions

Convective Instability in Slip Flow in a Vertical Circular Porous Microchannel

An Integral Method for Natural Convection of Van Der Waals Gases over a Vertical Plate

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