Entropy generation in a hollow cylinder with temperature dependent thermal conductivity and internal heat generation with convective–radiative surface cooling

Karimi

2015

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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: Entropy Generationmentioning

confidence: 99%

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

Karimi

2015

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“…For the one-dimensional pure conduction heat transfer, the general volumetric entropy generation rate can be written as [7,14,26] …”

Section: Entropy Generationmentioning

confidence: 99%

“…In heat transfer processes the entropy production may be result of any modes of heat transfer, i.e., conduction [7], convection [8e10] and radiation [11]. Other important factors are viscous effects [8e10] and magnetic fields [12].…”

Section: Introductionmentioning

confidence: 99%

“…After rigorous mathematical modeling, local and total entropy generation rates were plotted for asymmetric cooled slab with the temperaturedependent internal heat generation [27]. Torabi and Aziz [7] considered hollow cylindrical geometries with the radiation effect. To solve the energy equation and obtain the entropy generation, the differential transformation method was used.…”

Section: Introductionmentioning

confidence: 99%

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Temperature distribution, local and total entropy generation analyses in asymmetric cooling composite geometries with multiple nonlinearities: Effect of imperfect thermal contact

Yang

et al. 2014

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“…Many studies have opted in favor of the entropy generation analysis in pure conductive media [21e24]. They have considered pure conductive media with [25] or without [23] convection and/or radiation effects, functionally graded material [26], composite structures [27,28], etc. If a conductive part of a thermal system is considered, the only fact which causes entropy generation within the system is heat transport through the medium, i.e., temperature distribution within the conductive part.…”

Section: Introductionmentioning

confidence: 99%

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

2015

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