Papers by Javad Abolfazli Esfahani
An analytical solution for a power law non-Newtonian
fluid plus entropy generation analysis in a... more An analytical solution for a power law non-Newtonian
fluid plus entropy generation analysis in a journal
bearing is presented. According the rules of scale up the
general form of momentum equation is so simplified
that can be solved integrally. No slip condition is
applied on the walls. Finally velocity profile is
calculated and a worthwhile discussion is done on the
variation of velocity in the domain. Furthermore, the
entropy generation number is calculated using the
viscous dissipation function. Whereas a non-Newtonian
fluid is used a general form of viscous dissipation
function is introduced which is applicable for all kind of
Newtonian and non-Newtonian fluids. According the
entropy generation minimization principle, the optimum
condition for the bearing characteristic parameters and
lubricant non-Newtonian factor is studied. It is found
bearing geometry and non-Newtonian parameter
influence in entropy generation. Also it is found a fluid
with shear-thinning behavior which is well called as
Pseudoplastic fluid is the best lubricant from the entropy
generation minimization view point.
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In this paper, the effects of partitioning in solar still on performance recovery are investigate... more In this paper, the effects of partitioning in solar still on performance recovery are investigated experimentally and numerically. Two single slope solar stills containing conventional and modified by installing a
partition are fabricated and tested, simultaneously. Two stills have a same basin area. All experiments were performed in Semnan with geographical coordinates of 35 330 N, 53 230 E, Iran. Hourly temperature, productivity, and efficiency for the modified and conventional stills are obtained and compared.
Moreover, a numerical simulation based on SIMPLE algorithm is utilized and different contours are drawn to more discuss about the physics of this problem. Finally, a cost analysis is performed to investigate the
modified still, economically. It is found that the partitioned still works at much higher temperature difference between water and the condensing area especially for afternoon hours. Moreover, the productivity increases by installing the partition in the still. These enhancements are about 4.81%, 4.82%, 5.62%, and 8.16% for first, second, third, and fourth days of the experiment, respectively. Finally, the cost analysis studies reveal that the costs per liter of the fresh water production for the conventional and modified stills are 0.0096 and 0.0104 $/L/m2, respectively.
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Entropy, 2016
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Data Revues 16310721 V340i7 S163107211200068x, Jun 30, 2012
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Applied Thermal Engineering, 2016
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International Journal of Exergy Ijex, Mar 12, 2013
ABSTRACT In this paper, micro-/nano-Couette flow is considered with a special focus on entropy an... more ABSTRACT In this paper, micro-/nano-Couette flow is considered with a special focus on entropy and entropy generation rate in the framework of the entropy transport equation using direct simulation Monte Carlo (DSMC) method. To investigate the entropy generation behaviour, three different models, i.e., equilibrium thermodynamics-base (ETB), non-equilibrium thermodynamics-base (NETB) and a proposed 'combined model', are applied and the ranges of validity of the employed models are discussed. Effects of compressibility and rarefaction on entropy and entropy generation behaviours are investigated. We also suggest 'specific entropy generation' as a tool for detecting non-equilibrium regions including Knudsen layer.
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Journal of Statistical Physics, 2015
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This paper employs large eddy simulation (LES) to investigate non-premixed flameless oxidati... more This paper employs large eddy simulation (LES) to investigate non-premixed flameless oxidation occurring in the IFRF furnace with varying fuel-injection angle. In order to model radiation and combustion using OpenFOAM software, finite volume discrete ordinate model and partially stirred reactor are applied whereas the detailed
mechanism GRI-2.11 is undertaken represent chemistry reactions. The obtained results are compared with the
experimental measurements of Mancini’s et al. After ensuring the accuracy of the LES method, the combustion
characteristics are examined when using different fuel injection angles into the combustion chamber. The results explain using fuel injection with an angle into the combustion chamber, the net rate of reaction and entropy
generation increases.
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International Journal of Numerical Methods for Heat & Fluid Flow, 2015
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Journal of Magnetism and Magnetic Materials
This paper presents forced convective heat transfer in a channel with a built-in square obstacle.... more This paper presents forced convective heat transfer in a channel with a built-in square obstacle. The governing equations with the boundary conditions are solved using a finite volume method. The computations were done for a fixed blockage ratio (S ¼1/8) at Pr ¼0.71, and Reynolds (Re) and Stuart (N) numbers ranging from 1 to 250 and 0 to 10, respectively. The results are presented to show the effect of the channel walls and streamwise magnetic field at different Reynolds numbers on forced convection heat transfer from a square cylinder. A correlation is obtained for Nusselt number, in which the effect of a magnetic field is taken into account. The obtained results revealed that the existence of channel walls decreases the effects of magnetic field on Nusselt number. It also showed that by increasing Stuart number the thickness of thermal boundary layer increases and the convective heat transfer decreases. &
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Thermophysics and Aeromechanics, 2013
ABSTRACT In the present work, conjugate heat transfer in a rectangular cavity with a heated movin... more ABSTRACT In the present work, conjugate heat transfer in a rectangular cavity with a heated moving lid is investigated using the lattice Boltzmann method (LBM). The simulations are performed for incompressible flow, with Reynolds numbers ranging from 100 to 500, thermal diffusivity ratios ranging from 1 to 100, and Prandtl numbers ranging from 0.7 to 7. A uniform heat flux through the top of the lid is assumed. Results show that LBM is suitable for the study of heat transfer in conjugate problems. Effects of the Reynolds number, the Prandtl number and the thermal diffusivity ratio on hydrodynamic and thermal characteristics are investigated and discussed. The streamlines and temperature distribution in flow field, dimensionless temperature and Nusselt number along the hot wall are illustrated. The results indicate that increase of thermal diffusivity yields the removal of a higher quantity of energy from lid and its temperature decreases when increasing the Reynolds and the Prandtl numbers.
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Journal of Thermophysics and Heat Transfer, 2015
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Energy, 2015
ABSTRACT Convective heat transfer of Al2O3–water nanofluid over an equilateral triangular obstacl... more ABSTRACT Convective heat transfer of Al2O3–water nanofluid over an equilateral triangular obstacle with an optimization analysis is carried out to determine the optimum conditions for the maximum heat transfer rate and the minimum drag coefficient. Orientations of the obstacle, values of the solid volume fraction, and Reynolds number are selected as the input parameters. The analysis is performed according to the Response Surface Methodology. The response surface equation is obtained using the design of the experiments features. Two-dimensional unsteady equations with the relevant boundary conditions have been solved using finite volume method. Three different orientations of the triangular obstacle are defined for the optimization procedure. The computational simulations are done for different Reynolds numbers ( ), solid volume fractions ( ) and orientations of the triangular obstacle ( ). Also, a comparison is performed between the results of CFD analysis and Response Surface Methodology. It is found that the minimum drag coefficient is occurred at θ = 35.13°, Re = 97.6 and φ = 0.01 and the maximum Nusselt number is found at θ = 8.49°, Re = 180 and φ = 0.05.
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Journal of Magnetism and Magnetic Materials
In this article the finite volume method (FVM) is carried out to simulate the flow around and thr... more In this article the finite volume method (FVM) is carried out to simulate the flow around and through a two-dimensional porous cylinder. An external magnetic field is used to control the wake behind the bluff body and also to suppress the vortex shedding phenomena. The Darcy–Brinkman–Forchheimer model has been used for modeling the flow in the porous medium. Effects of Stuart (N), Reynolds (Re) and Darcy (Da) numbers on the flow behavior have been investigated. The results show that the critical Stuart number for suppress vortex shedding decreases with increasing the Darcy numbers. Also, the Stuart number for disappearance the re-circulating wake increases with increased Reynolds number for both porous and solid cylinders.
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Papers by Javad Abolfazli Esfahani
fluid plus entropy generation analysis in a journal
bearing is presented. According the rules of scale up the
general form of momentum equation is so simplified
that can be solved integrally. No slip condition is
applied on the walls. Finally velocity profile is
calculated and a worthwhile discussion is done on the
variation of velocity in the domain. Furthermore, the
entropy generation number is calculated using the
viscous dissipation function. Whereas a non-Newtonian
fluid is used a general form of viscous dissipation
function is introduced which is applicable for all kind of
Newtonian and non-Newtonian fluids. According the
entropy generation minimization principle, the optimum
condition for the bearing characteristic parameters and
lubricant non-Newtonian factor is studied. It is found
bearing geometry and non-Newtonian parameter
influence in entropy generation. Also it is found a fluid
with shear-thinning behavior which is well called as
Pseudoplastic fluid is the best lubricant from the entropy
generation minimization view point.
partition are fabricated and tested, simultaneously. Two stills have a same basin area. All experiments were performed in Semnan with geographical coordinates of 35 330 N, 53 230 E, Iran. Hourly temperature, productivity, and efficiency for the modified and conventional stills are obtained and compared.
Moreover, a numerical simulation based on SIMPLE algorithm is utilized and different contours are drawn to more discuss about the physics of this problem. Finally, a cost analysis is performed to investigate the
modified still, economically. It is found that the partitioned still works at much higher temperature difference between water and the condensing area especially for afternoon hours. Moreover, the productivity increases by installing the partition in the still. These enhancements are about 4.81%, 4.82%, 5.62%, and 8.16% for first, second, third, and fourth days of the experiment, respectively. Finally, the cost analysis studies reveal that the costs per liter of the fresh water production for the conventional and modified stills are 0.0096 and 0.0104 $/L/m2, respectively.
mechanism GRI-2.11 is undertaken represent chemistry reactions. The obtained results are compared with the
experimental measurements of Mancini’s et al. After ensuring the accuracy of the LES method, the combustion
characteristics are examined when using different fuel injection angles into the combustion chamber. The results explain using fuel injection with an angle into the combustion chamber, the net rate of reaction and entropy
generation increases.
fluid plus entropy generation analysis in a journal
bearing is presented. According the rules of scale up the
general form of momentum equation is so simplified
that can be solved integrally. No slip condition is
applied on the walls. Finally velocity profile is
calculated and a worthwhile discussion is done on the
variation of velocity in the domain. Furthermore, the
entropy generation number is calculated using the
viscous dissipation function. Whereas a non-Newtonian
fluid is used a general form of viscous dissipation
function is introduced which is applicable for all kind of
Newtonian and non-Newtonian fluids. According the
entropy generation minimization principle, the optimum
condition for the bearing characteristic parameters and
lubricant non-Newtonian factor is studied. It is found
bearing geometry and non-Newtonian parameter
influence in entropy generation. Also it is found a fluid
with shear-thinning behavior which is well called as
Pseudoplastic fluid is the best lubricant from the entropy
generation minimization view point.
partition are fabricated and tested, simultaneously. Two stills have a same basin area. All experiments were performed in Semnan with geographical coordinates of 35 330 N, 53 230 E, Iran. Hourly temperature, productivity, and efficiency for the modified and conventional stills are obtained and compared.
Moreover, a numerical simulation based on SIMPLE algorithm is utilized and different contours are drawn to more discuss about the physics of this problem. Finally, a cost analysis is performed to investigate the
modified still, economically. It is found that the partitioned still works at much higher temperature difference between water and the condensing area especially for afternoon hours. Moreover, the productivity increases by installing the partition in the still. These enhancements are about 4.81%, 4.82%, 5.62%, and 8.16% for first, second, third, and fourth days of the experiment, respectively. Finally, the cost analysis studies reveal that the costs per liter of the fresh water production for the conventional and modified stills are 0.0096 and 0.0104 $/L/m2, respectively.
mechanism GRI-2.11 is undertaken represent chemistry reactions. The obtained results are compared with the
experimental measurements of Mancini’s et al. After ensuring the accuracy of the LES method, the combustion
characteristics are examined when using different fuel injection angles into the combustion chamber. The results explain using fuel injection with an angle into the combustion chamber, the net rate of reaction and entropy
generation increases.