Temperature distribution, local and total entropy generation analyses in MHD porous channels with thick walls

Torabi, Mohsen; Zhang, Kaili

doi:10.1016/j.energy.2015.05.009

Cited by 34 publications

(26 citation statements)

References 37 publications

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“…The correctness of the solution procedure has been verified repeatedly in our previous works [42,56]. The solution for the temperature distribution with LTE model is straightforward and much simpler than the elaborated procedure taken for LTNE model and is therefore not reported here.…”

Section: Velocity and Temperature Fieldsmentioning

confidence: 97%

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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Section: Velocity and Temperature Fieldsmentioning

confidence: 97%

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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“…The validity of this assumption has been shown in a number of recent investigations of the systems with similar configurations to that of Figure 1 [19,[35][36][37][38][39], and hence is not further discussed here. In particular, this assumption is very realisable in the limit of low thermal Peclet number, which is frequently reached in microreactors [3].…”

Section: Governing Equationsmentioning

confidence: 97%

“…Each of these equations can be solved analytically by a straightforward mathematical manipulation and integration. Regarding Equations (13b) and (13c), which are coupled together, an algebraic manipulation leads to Equations (19) and (20). By applying the boundary conditions, the particular solution for each specific case of the investigated microchannels can be found.…”

Section: Solution Of Momentum Energy and Dispersion Equationsmentioning

confidence: 99%

“…Further, comprehensive analyses were conducted on the effects of different parameters upon the second law behaviour of the system. Later, Torabi and Zhang [19] performed a second law analysis of forced convection in a porous channel with internal heat generation and magnetic effects. The Local Thermal Equilibrium (LTE) model for thermal analysis of the porous section of the microchannel was used in this investigation.…”

Section: Introductionmentioning

confidence: 99%

“…The Local Thermal Equilibrium (LTE) model for thermal analysis of the porous section of the microchannel was used in this investigation. The solid walls were incorporated in the simulations of Torabi and Zhang [19] for the first time. It was demonstrated that thickness of the walls has strong influence on the thermal and entropic behaviours of the microchannel.…”

Section: Introductionmentioning

confidence: 99%

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Non-Equilibrium Thermodynamic Analysis of Double Diffusive, Nanofluid Forced Convection in Catalytic Microreactors with Radiation Effects

Govone

Torabi

Hunt

et al. 2017

Entropy

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This paper presents a theoretical investigation of the second law performance of double diffusive forced convection in microreactors with the inclusion of nanofluid and radiation effects. The investigated microreactors consist of a single microchannel, fully filled by a porous medium. The transport of heat and mass are analysed by including the thick walls and a first order, catalytic chemical reaction on the internal surfaces of the microchannel. Two sets of thermal boundary conditions are considered on the external surfaces of the microchannel; (1) constant temperature and (2) constant heat flux boundary condition on the lower wall and convective boundary condition on the upper wall. The local thermal non-equilibrium approach is taken to thermally analyse the porous section of the system. The mass dispersion equation is coupled with the transport of heat in the nanofluid flow through consideration of Soret effect. The problem is analytically solved and illustrations of the temperature fields, Nusselt number, total entropy generation rate and performance evaluation criterion (PEC) are provided. It is shown that the radiation effect tends to modify the thermal behaviour within the porous section of the system. The radiation parameter also reduces the overall temperature of the system. It is further demonstrated that, expectedly, the nanoparticles reduce the temperature of the system and increase the Nusselt number. The total entropy generation rate and consequently PEC shows a strong relation with radiation parameter and volumetric concentration of nanoparticles.

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Influence of conjugate heat transfer on the minimization of entropy generation for forced convective flow through parallel plate channel filled with porous material

Borah

Pati

2021

Heat Trans

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A fluid–solid conjugate heat transfer model is developed to analyze the characteristics of entropy generation for forced convective steady hydrodynamically fully developed laminar flow of a Newtonian fluid through a parallel plate channel filled with porous material by modulating the following parameters: substrate thickness, the ratio of thermal conductivity of wall to fluid, Biot number, the axial temperature gradient in the fluid, and Peclet number. The exteriors of both the walls are subjected to the thermal boundary conditions of the third kind. The mass and Brinkman momentum conservation equations in the fluidic domain and the coupled energy conservation in both the solid and fluidic domain are solved analytically using the local thermodynamic equilibrium model, so as to derive closed‐form expressions for the velocity in the fluid and the temperature both in the fluid and solid walls in terms of relevant parameters. Suitable combinations of influencing factors, namely the geometric parameters of the system, fluid, flow, and substrate properties are identified for which global entropy generation rate is minimized. The findings may be helpful in the design of thermal systems frequently used in diverse engineering applications having heat transfer in the solid wall being a crucial parameter.

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Temperature distribution, local and total entropy generation analyses in MHD porous channels with thick walls

Cited by 34 publications

References 37 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

Non-Equilibrium Thermodynamic Analysis of Double Diffusive, Nanofluid Forced Convection in Catalytic Microreactors with Radiation Effects

Influence of conjugate heat transfer on the minimization of entropy generation for forced convective flow through parallel plate channel filled with porous material

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