Analytical interpretation of the local thermal non-equilibrium condition of porous media imbedded in tube heat exchangers

Dehghan, Maziar; Jamal-Abad, Milad Tajik; Rashidi, Saman

doi:10.1016/j.enconman.2014.05.074

Cited by 84 publications

(30 citation statements)

References 27 publications

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“…Comparisons were, further, made with the previously published works and good agreements were observed [25,26].…”

Section: Introductionmentioning

confidence: 91%

“…One of the pioneering works in this area was done by Nield [13]. Following Nield's persuasive work, many scholars have tried to re-examine thermal porous systems from the LTNE perspective [18][19][20][21][22][23][24][25][26]. Bortolozzi and…”

Section: Introductionmentioning

confidence: 99%

“…Through using the classical definition of the thermal entry length on the basis of Nusselt number, the dimensionless thermal entry length was predicted [24]. Dehghan et al [25,26] considered both Darcy and Forchheimer terms in the momentum equation but neglected the viscous dissipation in the energy equation. Perturbation technique was employed by these authors to tackle the resultant nonlinear governing equations [25,26] and semi-analytical solutions for the temperature and Nusselt number were derived.…”

Section: Introductionmentioning

confidence: 99%

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Heat transfer and second law analyses of forced convection in a channel partially filled by porous media and featuring internal heat sources

Torabi

Karimi

Zhang

2015

Energy

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This paper provides a comprehensive study on the heat transfer and entropy generation rates in a channel partially filled with a porous medium and under constant wall heat flux. The porous inserts are attached to the walls of the channel and the system features internal heat sources due to exothermic or endothermic physical or physicochemical processes. Darcy-Brinkman model is used for modelling the transport of momentum and an analytical study on the basis of local thermal non-equilibrium (LTNE) condition is conducted. Further analysis through considering the simplifying, local thermal equilibrium (LTE) model is also presented. Analytical solutions are, first, developed for the velocity and temperature fields. These are subsequently incorporated into the fundamental equations of entropy generation and both local and total entropy generation rates are investigated for a number of cases. It is argued that, comparing with LTE, the LTNE approach yields more accurate results on the temperature distribution within the system and therefore reveals more realistic Nusselt number and entropy generation rates. In keeping with the previous investigations, bifurcation phenomena are observed in the temperature field and rates of entropy generation. It is, further, demonstrated that partial filling of the channel leads to a substantial reduction of the total entropy generation. The results also show that the exothermicity or endothermicity characteristics of the system have significant impacts on the temperature fields, Nusselt number and entropy generation rates.

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“…Comparisons were, further, made with the previously published works and good agreements were observed [25,26].…”

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Heat transfer and second law analyses of forced convection in a channel partially filled by porous media and featuring internal heat sources

Torabi

Karimi

Zhang

2015

Energy

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“…They used perturbation methods to represent dimensionless velocity and temperature distributions at iso-flux boundary conditions. Dehghan et al [13,14] investigated forced convection in a plane channel and tube filled with porous media. The local thermal non-equilibrium condition for energy equations was assumed and a new dimensionless number was introduced in order to representing the intensity of the LTNE condition.…”

Section: Introductionmentioning

confidence: 99%

Variable conductivity in forced convection for a tube filled with porous media: A perturbation solution

Jamal-Abad

Saedodin

Aminy

2018

Ain Shams Engineering Journal

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In this study, the forced convective in a tube filled with porous media is investigated analytically based on the perturbation methods. Thermal conductivity of the medium is assumed to be a linear function of radius. The Brinkman-Forchheimer-extended Darcy and local thermal equilibrium models are applied for momentum and energy equations. Analytical expressions for the temperature profile and Nusselt number as functions of porous medium shape parameter and thermal conductivity variation parameter are introduced. An analytical expression of the Nusselt number based on a variable conductivity with radius for the extended model of Darcy-Brinkman-Forchhei mer has not been previously proposed, and the present study aims at filling this gap. The effects of porous media shape parameter (s), Forchheimer number (F) and linear parameter of conductivity (e) on the Nusselt number and temperature profile are discussed. Results show that the Nusselt number increases with a linear increase in the thermal conductivity of the medium. Ó 2016 Faculty of Engineering, Ain Shams University. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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“…Although this method has been reported to be accurate for some certain circumstance, [11][12][13] the LTNE model with two energy equations for fluid and solid is more applicable when substantial temperature difference exists between the solid and the fluid. This method was adopted by many researchers such as Mahmoudi and Maerefat, 14 Dehghan et al, 15 and Buonomo et al 16 and has been proved to be accurate. Moreover, a more recent research carried out by Mahmoudi 17 shows that the thermal radiation from solid phase in a porous media also played an important role in the temperature field within a porous/fluid system; the ignorance of the thermal radiation will lead to a substantial error in temperature prediction.…”

Section: Introductionmentioning

confidence: 99%

Numerical simulation of condensation in microchannels between spherical particles

Liu

Peng

Ling

et al. 2016

Advances in Mechanical Engineering

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In this article, a numerical investigation of vapor condensation in a two-dimensional ordered microchannel was conducted with computational fluid dynamics software Fluent. A simplified physical model was built up to simulate a rectangular channel filled with particles. A constant wall heat flux was added to the side walls of the rectangular channel. Volume of fluid model was adopted to pursue the interface of the gas and liquid. The results showed that a better heat transfer performance could be obtained with the porous structure. The local heat transfer coefficient obtained from simulation was in good accordance with the former experimental data, which increased with the increase in fluid velocity and decreased along the flow direction. Parametric analyses were conducted concerning the effects of initial vapor velocity u 0 , initial temperature T 0 , and wall heat flux q w on local heat transfer coefficient. The velocity u 0 played a significant role during the process of condensation. Temperature distributions along the porous channel and side walls were also analyzed. The results showed that the temperature decreased along the flow direction and increased with the increase in fluid velocity.

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Analytical interpretation of the local thermal non-equilibrium condition of porous media imbedded in tube heat exchangers

Cited by 84 publications

References 27 publications

Heat transfer and second law analyses of forced convection in a channel partially filled by porous media and featuring internal heat sources

Heat transfer and second law analyses of forced convection in a channel partially filled by porous media and featuring internal heat sources

Variable conductivity in forced convection for a tube filled with porous media: A perturbation solution

Numerical simulation of condensation in microchannels between spherical particles

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