Radiation Combined with Conduction and Convection

Modest, Michael F.

doi:10.1016/b978-0-12-386944-9.50022-4

Cited by 5 publications

(4 citation statements)

References 303 publications

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“…Using Rosseland approximation [36] the last term of the energy equation for the solid phase of the porous section of the microchannel is transformed to:…”

Section: Governing Equationsmentioning

confidence: 99%

“…The radiative heat flux from the solid phase of the porous medium is caused by the solid phase having the ability to lose (or absorb) heat through radiation. In the current model, the fluid is assumed to be transparent to radiation, which is readily justifiable by considering the fact that most fluids are optically highly transparent [36]. Of course, that is not to say that the fluid phase is unaffected by the radiative heat loss form the solid phase, merely that the effect is indirect.…”

Section: Governing Equationsmentioning

confidence: 99%

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Two-dimensional heat and mass transfer and thermodynamic analyses of porous microreactors with Soret and thermal radiation effects—An analytical approach

Hunt

Torabi

Govone

et al. 2018

Chemical Engineering and Processing - Process Intensification

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Transport of heat and mass and the thermodynamics of porous microreactors with thermal diffusion and radiation effects are investigated analytically. The examined configuration includes an axisymmetric, thickwall microchannel with an iso-flux thermal boundary condition imposed on the external surfaces. The microchannel is filled with porous materials and accommodates a zeroth order homogenous chemical reaction. Internal radiative heat transfer is modelled in addition to heat convection and conduction, while the local thermal non-equilibrium approach is taken within the porous section of the system. The transport of species is coupled with that of heat via the inclusion of thermodiffusion or Soret effect. Two-dimensional heat and mass transfer differential equations are solved analytically. The results are subsequently used to predict the thermodynamic irreversibilities inside the reactor and a thorough analysis of local and total entropy generation rates is performed. Also, the changes in Nusselt number, calculated on the internal walls of the microreactor, versus various parameters are reported. It is shown that the radiation effects can impact the temperature of the solid phase of the porous medium and lead to alteration of Nusselt number. It is further observed that the transfer of mass is the main source of irreversibility in the system. The findings are of particular use for the design and analysis of the microreactors with homogenous chemical reactions and can be also used for the validation of computational models.

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“…Using Rosseland approximation [36] the last term of the energy equation for the solid phase of the porous section of the microchannel is transformed to:…”

Section: Governing Equationsmentioning

confidence: 99%

Section: Governing Equationsmentioning

confidence: 99%

Two-dimensional heat and mass transfer and thermodynamic analyses of porous microreactors with Soret and thermal radiation effects—An analytical approach

Hunt

Torabi

Govone

et al. 2018

Chemical Engineering and Processing - Process Intensification

View full text Add to dashboard Cite

show abstract

“…The following simplifications were assumed: (i) density is constant apart from the linear density-temperature relation in the Boussinesq approximation, (ii) same density for the solid and liquid phases, (iii) the natural convection flow is laminar (for the third modeling, turbulent flow was considered), incompressible and inviscid flow, (iv) internal thermal radiation is negligible as the Boltzmann number >> 1, i.e. ~ 10 4 , as suggested by Modest [13].…”

Section: Governing Equationsmentioning

confidence: 99%

Numerical study of melting process of a high-temperature phase change material including natural convection and turbulence

Riahi¹,

Saman²,

Bruno³

et al. 2017

Int. J. CMEM

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The design and optimisation of a latent heat thermal storage system require knowledge of flow, heat and mass transfer during the melting (charging) and solidification (discharging) processes of hightemperature phase change materials (PCMs). Using fluent, numerical modeling was performed to study the impact of natural convection and turbulence in the melting process of a high-temperature PCM in a latent heat storage system with Ra = 10 12. Numerical calculation was conducted, considering a two dimensional symmetric grid of a dual-tube element in a parallel flow shell and tube configuration where the heat transfer fluid passes through the tube and PCM fills the shell. Three melting processes of PCM were considered; pure conduction, conduction and natural convection, and finally the latter with turbulence. The first study showed a one dimensional melt front, evolving parallel to the tube, which results in lower peak temperatures and temperature gradients, higher heat transfer area for a longer period of time, however lower heat transfer rate due to natural convection being ignored. The second study presented a two dimensional melt front which evolves mainly perpendicular to the tube, shrinking downward, resulting in the loss of heat transfer area and higher peak temperatures and temperature gradient, however, the higher rate of heat transfer rate due to the creation of convection cells which facilitate mass and heat transfer. Including turbulence led to a higher mixing effect due to the higher velocity of convection cells, resulting in a more uniform process with lower peak temperature and temperature gradients and higher heat transfer rate. In a melting process with Ra>10 11 , including convection and turbulence impact provides more realistic data of flow, mass and heat transfer.

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“…Benefit by invention of digital computers and the development in code languages (i.e. FORTRAN, C, C++, etc), pioneering works on field models, also known as computational fluid dynamics (CFD) models for fire safety studies were proposed by Ku et al [1], Hasemi [2], Yang and Chang (i.e. UNDSAFE-I model) [3] during the late 1970s.…”

Section: Introductionmentioning

confidence: 99%

Comparison of detailed soot formation models for sooty and non-sooty flames in an under-ventilated ISO room

Yuen

Yeoh

Timchenko

et al. 2017

International Journal of Heat and Mass Transfer

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Radiation Combined with Conduction and Convection

Cited by 5 publications

References 303 publications

Two-dimensional heat and mass transfer and thermodynamic analyses of porous microreactors with Soret and thermal radiation effects—An analytical approach

Two-dimensional heat and mass transfer and thermodynamic analyses of porous microreactors with Soret and thermal radiation effects—An analytical approach

Numerical study of melting process of a high-temperature phase change material including natural convection and turbulence

Comparison of detailed soot formation models for sooty and non-sooty flames in an under-ventilated ISO room

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