Analytical investigation of porous pin fins with variable section in fully-wet conditions

Vahabzadeh, A.; Ganji, D.D.; Abbasi, Morteza

doi:10.1016/j.csite.2014.11.002

Cited by 55 publications

(31 citation statements)

References 20 publications

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“…The dimensionless velocity distribution for the separation region, which is adjacent to the separation point (corresponds to (αRe) sep. ), is obtained by the solution of Eq. (6) using the least square method (Moakher et al, 2016;Vahabzadeh et al, 2015). Owing to that the boundary conditions must satisfy the trial solution; the trial solution can be assumed as…”

Section: Least Square Methodsmentioning

confidence: 99%

Boundary-layer separation in circular diffuser flows in the presence of an external non-uniform magnetic field

et al. 2020

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Abstract. The focus of the present work is on the investigation of the separation point and its relative location in a circular diffuser carrying incompressible laminar flow in the presence of a non-uniform external magnetic field. Two different approaches are deployed in the present analysis. In the first approach, a similarity transform is applied to reduce the momentum equation to the nonlinear ordinary differential equation (ODE). The ODE is solved by a dual integral–numerical method and the separation position is directly determined. In this combined numerical–integral methodology, the integration is applied followed by a numerical method. In the second approach, the equation is solved by the least square method (LSM), and the separation position is indirectly specified. In this study it is shown that the magnetic field intensity can be manipulated to postpone the separation such that it could be eliminated totally. Comparing the results yields a good agreement. It has been concluded that by increasing the magnetic field intensity, as the Lorentz force increases, increased shear stress on the wall and delay in the occurrence of the separation position are observed.

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Section: Least Square Methodsmentioning

confidence: 99%

Boundary-layer separation in circular diffuser flows in the presence of an external non-uniform magnetic field

et al. 2020

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“…It was observed that due to high values of fin efficiency, a rectangular fin should be used instead of convex and triangular sections. Vahabzadeh et al 110 analytically investigated porous fins with changing cross‐section in total wet conditions. The results showed that the least‐squares method is a convenient and powerful method in engineering problems.…”

Section: Computational With Analytical Combined Studiesmentioning

confidence: 99%

Improvement of heat transfer through fins: A brief review of recent developments

Maji¹,

Choubey

2020

Heat Trans

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Fins or extended surfaces are generally used in heat exchangers to enhance heat transfer between the main surface and ambient fluid. Various types of simple-shaped fins, namely, rectangular, square, annular, cylindrical, and tapered, have been used with different geometrical combinations. To satisfy industrial demand, different trials have also been carried out for designing optimized fins. The optimization of fins can be performed either by enhancing heat dissipation at an exact fin weight or by diminishing the weight of the fin by precise heat dissipation. Recently a notable amount of work on some typical fins, like, porous fins and perforated fins, has also been carried out. This paper presents a brief review on heat transfer enhancement using fins of different types considering variable thermophysical and geometric parameters, which will also be useful for future use of geometrical modifications of extended surfaces, based on the cost and availability of space.analytical approach, computational approach, experimental approach, perforated fin, porous fin | INTRODUCTIONAdvanced technologies need high-performance heat transfer equipment. Techniques for enhancing the heat transfer rate are classified into two categories: active and passive methods. In the design point of view, active methods are complex as they require some extraneous power input for necessary flow adjustments and to improve the heat transfer rate and thus applications are limited. On the other hand, passive methods require geometrical or surface adjustments to the flow passage by incorporating additional devices. Additionally, by interrupting or varying the existing flow behavior (except for extended surfaces); higher heat transfer coefficients are promoted through this method, which is also followed by an increase in the corresponding pressure drop. The amount of conduction, convection, and radiation of an object shows the amount of heat it transfers. The heat transfer rate is enhanced by increasing the temperature difference between the object and the environment or by enhancing the coefficient of convective heat transfer or by maximizing the surface area of the body. In some cases, it is not appropriate or cost effective to alter the first two options. Introducing a fin to a body, however, expands the surface area and sometimes this is a cost-effective solution for heat transfer problems. Extended surfaces or fins are illustrations of passive methods that are generally used in different industrial applications for the enhancement of heat transfer between the primary surface (heat sink) and the surrounding fluid. Currently reducing the cost and size of fins is the key target of the fin industry. This demand is generally met by the high-thermal-conductivity and costly metals used to fabricate finned surfaces. Many efforts have been made to construct optimized fins. (a) By changing the size and shape of the solid fin: Instead of a longitudinal rectangular solid fin, if the geometry of fin design is changed, the performance parameters and heat tr...

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“…Their results indicate that increasing the Reynolds and Hartman number is reduces the nanofluid flow velocity in the channel and the maximum amount of temperature increase and increasing the Prandtl and Eckert number will increase the maximum amount of temperature. Vahabzadeh et al [18] studied the temperature distribution, heat transfer rate, efficiency and optimization of porous pin fins in fully wet conditions. They applied the Least Square Method (LSM) to solve governing equations.…”

Section: Introductionmentioning

confidence: 99%

Investigation of heat transfer for cooling turbine disks with a non-Newtonian fluid flow using DRA

Dogonchi

Ganji

2015

Case Studies in Thermal Engineering

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a b s t r a c tA non-Newtonian viscoelastic fluid flow passes through the porous wall of an axisymmetric channel on a turbine disc for cooling application. The present article solves the couple equations (momentum and heat transfer) of a non-Newtonian fluid flow in an axisymmetric channel with a porous wall for turbine cooling applications by using the Duan-Rach Approach (DRA). The precious achievement of the present work is introducing a new and efficient approximate analytical technique that this method allows us to find a solution without using numerical methods to evaluate the undetermined coefficients. The approximate analytical investigation is carried out for different values of the embedding parameters namely: Reynolds number, Prandtl number, injection Reynolds number and power law index. The DRA results indicate that Nusselt number has direct relationship with Reynolds number, Prandtl number and power law index. Also the results were compared with numerical solution in order to verify the accuracy of the proposed method. It is seen that the current results in comparison with the numerical ones are in excellent agreement.

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Analytical investigation of porous pin fins with variable section in fully-wet conditions

Cited by 55 publications

References 20 publications

Boundary-layer separation in circular diffuser flows in the presence of an external non-uniform magnetic field

Boundary-layer separation in circular diffuser flows in the presence of an external non-uniform magnetic field

Improvement of heat transfer through fins: A brief review of recent developments

Investigation of heat transfer for cooling turbine disks with a non-Newtonian fluid flow using DRA

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