Abstract: The objective of this research work is to investigate
for one dimensional transient radiative transfer equations with
conduction using finite volume method. Within the infrastructure of
finite-volume, we obtain the conservative discretization of the terms
in order to preserve the overall conservative property of finitevolume
schemes. Coupling of conductive and radiative equation
resulting in fluxes is governed by the magnitude of emissivity,
extinction coefficient, and temperature of the medium as well as
geometry of the problem.
The problem under consideration has been solved, for a slab
dominating radiation coupled with transient conduction based on
finite volume method. The boundary conditions are also chosen so as
to give a good model of the discretized form of radiation transfer
equation. The important feature of the present method is flexibility in
specifying the control angles in the FVM, while keeping the
simplicity in the solution procedure.
Effects of various model parameters are examined on the
distributions of temperature, radiative and conductive heat fluxes and
incident radiation energy etc. The finite volume method is considered
to effectively evaluate the propagation of radiation intensity through
a participating medium.
Abstract: Radiative heat transfer in participating medium was
carried out using the finite volume method. The radiative transfer
equations are formulated for absorbing and anisotropically scattering
and emitting medium. The solution strategy is discussed and the
conditions for computational stability are conferred. The equations
have been solved for transient radiative medium and transient
radiation incorporated with transient conduction. Results have been
obtained for irradiation and corresponding heat fluxes for both the
cases. The solutions can be used to conclude incident energy and
surface heat flux. Transient solutions were obtained for a slab of heat
conducting in slab and by thermal radiation. The effect of heat
conduction during the transient phase is to partially equalize the
internal temperature distribution. The solution procedure provides
accurate temperature distributions in these regions. A finite volume
procedure with variable space and time increments is used to solve
the transient radiation equation. The medium in the enclosure
absorbs, emits, and anisotropically scatters radiative energy. The
incident radiations and the radiative heat fluxes are presented in
graphical forms. The phase function anisotropy plays a significant
role in the radiation heat transfer when the boundary condition is
non-symmetric.
Abstract: This study investigates how AlGaAs/GaAs thin film
solar cells perform under varying global solar spectrum due to the
changes of environmental parameters such as the air mass and the
atmospheric turbidity. The solar irradiance striking the solar cell is
simulated using the spectral irradiance model SMARTS2 (Simple
Model of the Atmospheric Radiative Transfer of Sunshine) for clear
skies on the site of Setif (Algeria). The results show a reduction in the
short circuit current due to increasing atmospheric turbidity, it is
63.09% under global radiation. However increasing air mass leads to
a reduction in the short circuit current of 81.73%. The efficiency
decreases with increasing atmospheric turbidity and air mass.
Abstract: The radiation effect within the solid anode, electrolyte, and cathode SOFC layers problem has been investigated in this paper. Energy equation is solved by the Lattice Boltzmann method (LBM). The Rosseland method is used to model the radiative transfer in the electrodes. The Schuster-Schwarzschild method is used to model the radiative transfer in the electrolyte. Without radiative effect, the found results are in good agreement with those published. The obtained results show that the radiative effect can be neglected.
Abstract: The objective of this work is to investigate the
turbulent reacting flow in a three dimensional combustor with
emphasis on the effect of inlet swirl flow through a numerical
simulation. Flow field is analyzed using the SIMPLE method which is
known as stable as well as accurate in the combustion modeling, and
the finite volume method is adopted in solving the radiative transfer
equation. In this work, the thermal and flow characteristics in a three
dimensional combustor by changing parameters such as equivalence
ratio and inlet swirl angle have investigated. As the equivalence ratio
increases, which means that more fuel is supplied due to a larger inlet
fuel velocity, the flame temperature increases and the location of
maximum temperature has moved towards downstream. In the mean
while, the existence of inlet swirl velocity makes the fuel and
combustion air more completely mixed and burnt in short distance.
Therefore, the locations of the maximum reaction rate and temperature
were shifted to forward direction compared with the case of no swirl.
Abstract: A numerical study on the heat transfer in the thermal
barrier coatings and the substrates of a parallel-plate enclosure is
carried out. Some of the thermal barrier coatings, such as ceramics, are
semitransparent and are of interest for high-temperature applications
where radiation effects are significant. The radiative transfer equations
and the energy equations are solved by using the discrete ordinates
method and the finite difference method. Illustrative results are
presented for temperature distributions in the coatings and the opaque
walls under various heating conditions. The results show that the
temperature distribution is more uniform in the interior portion of each
coating away from its boundary for the case with a larger average of
varying refractive index and a positive gradient of refractive index
enhances radiative transfer to the substrates.
Abstract: The process of laser absorption in the skin during
laser irradiation was a critical point in medical application
treatments. Delivery the correct amount of laser light is a critical
element in photodynamic therapy (PDT). More amounts of laser
light able to affect tissues in the skin and small amount not able to
enhance PDT procedure in skin. The knowledge of the skin tone
laser dependent distribution of 635 nm radiation and its penetration
depth in skin is a very important precondition for the investigation of
advantage laser induced effect in (PDT) in epidermis diseases
(psoriasis). The aim of this work was to estimate an optimum effect
of diode laser (635 nm) on the treatment of epidermis diseases in
different color skin. Furthermore, it is to improve safety of laser in
PDT in epidermis diseases treatment. Advanced system analytical
program (ASAP) which is a new approach in investigating the PDT,
dependent on optical properties of different skin color was used in
present work. A two layered Realistic Skin Model (RSM); stratum
corneum and epidermal with red laser (635 nm, 10 mW) were used
for irradiative transfer to study fluence and absorbance in different
penetration for various human skin colors. Several skin tones very
fair, fair, light, medium and dark are used to irradiative transfer. This
investigation involved the principles of laser tissue interaction when
the skin optically injected by a red laser diode. The results
demonstrated that the power characteristic of a laser diode (635 nm)
can affect the treatment of epidermal disease in various color skins.
Power absorption of the various human skins were recorded and
analyzed in order to find the influence of the melanin in PDT
treatment in epidermal disease. A two layered RSM show that the
change in penetration depth in epidermal layer of the color skin has a
larger effect on the distribution of absorbed laser in the skin; this is
due to the variation of the melanin concentration for each color.
Abstract: Simultaneous transient conduction and radiation heat
transfer with heat generation is investigated. Analysis is carried out
for both steady and unsteady situations. two-dimensional gray
cylindrical enclosure with an absorbing, emitting, and isotropically
scattering medium is considered. Enclosure boundaries are assumed
at specified temperatures. The heat generation rate is considered
uniform and constant throughout the medium. The lattice Boltzmann
method (LBM) was used to solve the energy equation of a transient
conduction-radiation heat transfer problem. The control volume finite
element method (CVFEM) was used to compute the radiative
information. To study the compatibility of the LBM for the energy
equation and the CVFEM for the radiative transfer equation, transient
conduction and radiation heat transfer problems in 2-D cylindrical
geometries were considered. In order to establish the suitability of the
LBM, the energy equation of the present problem was also solved
using the the finite difference method (FDM) of the computational
fluid dynamics. The CVFEM used in the radiative heat transfer was
employed to compute the radiative information required for the
solution of the energy equation using the LBM or the FDM (of the
CFD). To study the compatibility and suitability of the LBM for the
solution of energy equation and the CVFEM for the radiative
information, results were analyzed for the effects of various
parameters such as the boundary emissivity. The results of the LBMCVFEM
combination were found to be in excellent agreement with
the FDM-CVFEM combination. The number of iterations and the
steady state temperature in both of the combinations were found
comparable. Results are found for situations with and without heat
generation. Heat generation is found to have significant bearing on
temperature distribution.