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Article

Mustafa Turkyilmazoglu

This paper aims to present an elegant exact solution in terms of elementary functions for a special pin fin without the classical length-of-arc approximation.

Abstract

Purpose

This paper aims to present an elegant exact solution in terms of elementary functions for a special pin fin without the classical length-of-arc approximation.

Design/methodology/approach

The temperature distribution along the fin and the surface function, both being the functions of a shape parameter, is inversely proportional to each other. The specialty of the spine is such that its shape and temperature profile are linked for a given Biot number.

Findings

Exact formulas for the pin fin tip temperature, pin fin base heat transfer rate, surface area of the spine and thermal fin efficiency are also given.

Originality/value

Without the traditional arc length assumption, the pin fin is shown to be an effective extended surface to remove the excessive heat from the hot surface it is pinned to. Optimum pin fin dimensions leading to the maximum base heat transfer rate are also worked out for a specified fin volume.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 30 no. 11
Type: Research Article
ISSN: 0961-5539

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Article

B.S. Shenstone

AS in the case of end‐plate fins, inset fins have the effect of increasing the effective aspect ratio of the tail plane, but to a somewhat less extent. The tail with fins

Abstract

AS in the case of end‐plate fins, inset fins have the effect of increasing the effective aspect ratio of the tail plane, but to a somewhat less extent. The tail with fins will be compared with an untwisted elliptical tail without fins, because this method of comparison is very clear and being also used to compare wings of different shapes is familiar to people concerned with aerodynamic problems.

Details

Aircraft Engineering and Aerospace Technology, vol. 11 no. 12
Type: Research Article
ISSN: 0002-2667

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Article

Erdem Cuce and Pinar Mert Cuce

The purpose of this paper is to investigate the effects of concavity level on performance parameters of a parabolic fin under the influences of natural convection and…

Abstract

Purpose

The purpose of this paper is to investigate the effects of concavity level on performance parameters of a parabolic fin under the influences of natural convection and radiation.

Design/methodology/approach

Computational fluid dynamics software (FLUENT) is used for the heat transfer analysis. Optimum fin geometry is searched in order to maximize the heat dissipation from fin to the ambient while minimizing the volume of fin.

Findings

The fin profile with concavity level of 2 dissipates 14.92, 17.53, 24.33 and 26.60 percent more heat and uses 34.62, 49.64, 57.66 and 63.09 percent much material compared to the fin with concavity level of 4, 6, 8 and 10, respectively. It is also observed that the amount of heat dissipation per mass considerably increases with increasing concaveness.

Research limitations/implications

The research was carried out for five different concavity levels in the range of 2-10.

Practical implications

The results can be used in passive cooling applications of PV systems. Also, heat sinks for CPU cooling can be redesigned with respect to the results obtained from the research.

Originality/value

In this paper, effects of concavity level on performance parameters of a parabolic fin are investigated for the first time. It is observed from the numerical results that the fin profile with higher concavity levels provides a cheaper and lighter heat dissipation device so it is recommended for the applications where the weight and the cost are primary considerations such as cooling of photovoltaics.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 23 no. 7
Type: Research Article
ISSN: 0961-5539

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Article

Bassam A/K and Abu‐Hijleh

The aim of this work is to determine the optimal number and location of the fin(s) for maximum laminar forced convection heat transfer from a cylinder with multiple high…

Abstract

Purpose

The aim of this work is to determine the optimal number and location of the fin(s) for maximum laminar forced convection heat transfer from a cylinder with multiple high conductivity radial fins on its outer surface in cross‐flow, i.e. Nusselt number, over a range of Reynolds numbers.

Design/methodology/approach

The effect of several combinations of number of fins, fin height, and fin(s) tangential location on the average Nusselt number was studied over the range of Reynolds numbers (5‐150). The problem was investigated numerically using finite difference method over a stretched grid. The optimal number and placement of the fins, for maximum Nusselt number, was determined for several combinations of Reynolds number and fin height. The percentage improvement in heat transfer per fin(s) unit length, i.e. cost‐efficiency, was also studied.

Findings

The results indicate that the fin(s) combination with the highest normalised Nusselt number is not necessarily the combination that results in the highest fin cost‐efficiency.

Originality/value

The results of the study can be used to design highly efficient cross‐flow forced convection heat transfer configurations from a horizontal cylinder with minimum cost.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 15 no. 3
Type: Research Article
ISSN: 0961-5539

Keywords

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Article

Y.P. Cheng, T.S. Lee and H.T. Low

In this paper three‐dimensional numerical simulations were conducted for the periodically developed laminar flow in the sinusoid wavy fin‐and‐tube heat exchanger.

Abstract

Purpose

In this paper three‐dimensional numerical simulations were conducted for the periodically developed laminar flow in the sinusoid wavy fin‐and‐tube heat exchanger.

Design/methodology/approach

A novel CLEARER algorithm is adopted to guarantee the fully coupling between the pressure and velocity, and it can not only speed up the convergence rate, but also overcome the severe grid non‐orthogonality in the wavy fin‐and‐tube heat exchanger. The influence of wave amplitude, fin pitch, tube diameter and wave density on fluid flow and heat transfer characteristics is analyzed under different Reynolds numbers.

Findings

The numerical results show that with the increase of wave amplitude, tube diameter or wave density, both the friction factor and Nusselt number will increase, and the increase rate of friction factor is higher than that of Nusselt number. It is interesting to note that, at low Reynolds numbers the Nusselt number increases with the decrease of fin pitch, while at high Reynolds numbers, the Nusselt number increases with the increase of fin pitch.

Originality/value

The numerical results presented in this paper may provide some useful guidance in the design of the wavy fin‐and‐tube heat exchanger with large number of rows of tubes.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 19 no. 6
Type: Research Article
ISSN: 0961-5539

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Article

Naoyuki Takesue, Youichi Hata and Tatsuhiko Sekiya

Underwater robots are one of the effective solutions for underwater exploration. Fish's swimming motion is more effective and efficient than propeller screw propulsion…

Abstract

Purpose

Underwater robots are one of the effective solutions for underwater exploration. Fish's swimming motion is more effective and efficient than propeller screw propulsion which is more popular for underwater vehicles. So far, a lot of fish‐like robots that have several actuated joints have been developed. They realize arbitrary motion by controlling the joint angles simultaneously. On the other hand, using an elastic fin may reduce the number of actuated joints and the total energy consumption. The purpose of this paper is to develop a fish‐like robot driven by a single actuator with an elastic tail fin.

Design/methodology/approach

Since an elastic plate appropriately bends due to the interaction to the surrounding fluid, a robot with the elastic fin can swim smoothly even though it has only a single actuated joint. However, in order to improve the swimming performances, it is required to optimize the shape of fin (width, thickness, distribution, etc.). Although computational fluid dynamics technique is one of the methods to assess the effectiveness of a certain shape of fin, it may take longer to obtain the results. Therefore, in this study, a simplified simulator is constructed and a better shape of fin is explored.

Findings

Four types of fin shape were prepared and the swimming experiments were conducted. The swimming velocity changed according to the frequency and the shape of fin. In order to find the optimal shape of fin, the simulator of five‐link model surrounded by fluid is constructed. The differences of velocity can be found according to the parameters of fin shape. The simulation showed the similar trend as the experiments although the absolute values of velocity did not correspond. It is thought that the developed simulator can estimate the relative performance of fins.

Originality/value

Most fish robots that have been developed so far consist of rigid links and multi‐actuated joints, which can realize arbitrary motion by controlling the joint angles simultaneously. On the other hand, using an elastic plate as a tail fin may reduce the number of actuated joints and the total energy consumption although it is not easy to realize arbitrary attitude. In this paper, a fish‐like robot driven by a single actuator with an elastic tail fin was developed. This technique makes the mechanism of a fish‐like robot simple.

Details

Industrial Robot: An International Journal, vol. 38 no. 3
Type: Research Article
ISSN: 0143-991X

Keywords

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Article

Tony W.H. Sheu and S.F Tsai

A three‐dimensional numerical study was conducted to assess the heat transfer performance of extended fins in a two‐row finned tube heat exchanger. Fins under…

Abstract

A three‐dimensional numerical study was conducted to assess the heat transfer performance of extended fins in a two‐row finned tube heat exchanger. Fins under investigation were plane and slit types. A finite volume discretization method and a SIMPLE‐based solution algorithm were, respectively, applied to working differential equations and their discrete counterparts to compute the gas velocities and pressure. The temperatures of solid and gas phases were computed from the same energy equation with different diffusivities and prescribed convective fluxes. The main objective of this study was to compare the transfer capabilities of the two investigated fin shapes. Their capabilities as a whole are presented in terms of the computed Nusselt number and the pressure drop across the flow passage.

Details

International Journal of Numerical Methods for Heat & Fluid Flow, vol. 9 no. 1
Type: Research Article
ISSN: 0961-5539

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Article

Kang Eu Ong, Kor Oon Lee, K.N. Seetharamu, I.A. Azid, G.A. Quadir, Z.A. Zainal and Teck Joo Goh

To find the optimal geometries of rectangular and cylindrical fins for maximum heat dissipation.

Abstract

Purpose

To find the optimal geometries of rectangular and cylindrical fins for maximum heat dissipation.

Design/methodology/approach

The objective function for finding the optimized profiles of fins are solved by using the genetic algorithms (GAs). A range of fin shapes are investigated and the optimum solutions for various profile area are obtained.

Findings

Provide information to thermal engineers to what extent any particular extended surface or fin arrangements could improve heat dissipation from a surface to the surrounding fluid. Smaller fin volume in fin design is preferable as the heat is dissipated more effectively.

Originality/value

A new method of using GA for optimization of fins is used here. The value of this paper lies in providing data for selecting suitable fins for thermal management in electronic systems.

Research limitations/implications

Limited to cases where the correlations for heat transfer coefficients are valid.

Practical implications

A very useful finding for practising thermal engineer especially in the area of electronic packaging as the parameters for the fin design can easily be found for any chosen profile area.

Details

Microelectronics International, vol. 22 no. 1
Type: Research Article
ISSN: 1356-5362

Keywords

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Book part

Raquel Meyer Alexander, Andrew Gross, G. Ryan Huston and Vernon J. Richardson

We investigate the interaction of debt covenants and tax accounting on the adoption of Financial Interpretation No. 48 (FIN 48). We examine how firms respond to the…

Abstract

We investigate the interaction of debt covenants and tax accounting on the adoption of Financial Interpretation No. 48 (FIN 48). We examine how firms respond to the potential tightening of covenant slack upon FIN 48 adoption and whether these actions are penalized by creditors and anticipated by equity markets. We find that upon FIN 48 adoption, the majority of sample corporate borrowers increase their tax reserves and reduce equity. Firms close to debt covenant violation were even more likely to increase tax reserves upon FIN 48 adoption; however, the size of the adjustment was relatively smaller, suggesting that the FIN 48 standards limited, but did not eliminate, firms use of discretion in reporting uncertain tax positions to avoid costly covenant violations. For firms near net worth debt covenant violation, the act of decreasing equity upon FIN 48 adoption imposes real economic costs, as the average cost of debt increased by 43 basis points. Finally, we extend prior research on the market response to FIN 48 by showing how the market response to FIN 48 adoption is a function of debt covenant slack and tax aggressiveness. Specifically, the cumulative abnormal return at the FIN 48 exposure draft release date is negative only for tax aggressive firms that are close to debt covenant violation.

Details

Advances in Taxation
Type: Book
ISBN: 978-1-78714-524-5

Keywords

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Article

Reza Ramezanpour Jirandeh, Mehrangiz Ghazi, Amir Farhang Sotoodeh and Mohammad Nikian

The purpose of this paper is to present a novel and applied method for optimum designing of plate-finned heat exchanger network. Considering the total annual cost as the…

Abstract

Purpose

The purpose of this paper is to present a novel and applied method for optimum designing of plate-finned heat exchanger network. Considering the total annual cost as the objective function, a network of plate-finned heat exchanger is designed and optimized.

Design/methodology/approach

Accurate evaluation of plate-finned heat exchanger networks depends on different fin types with 10 different geometrical parameters of heat exchangers. In this study, fin numbers are considered as the main decision variables and geometrical parameters of fins are considered as the secondary decision variables. The algorithm applies heat transfer and pressure drop coefficients correction method and differential evolution (DE) algorithm to obtain the optimum results. In this paper, optimization and minimization of the total annual cost of heat exchanger network is considered as the objective function.

Findings

In this study, a novel and applied method for optimum designing of plate-finned heat exchanger network is presented. The comprehensive algorithm is applied into a case study and the results are obtained for both counter-flow and cross-flow plate-finned heat exchangers. The total annual cost and total area of the network with counter-flow heat exchangers were 12.5% and 23.27%, respectively, smaller than the corresponding values of the network with cross-flow heat exchanger.

Originality/value

In this paper, a reliable method is used to design, optimize parameters and the economic optimization of heat exchanger network. Taking into account the importance of plate-finned heat exchangers in industrial applications and the complexity in their geometry, the DE methodology is adopted to obtain an optimal geometric configuration. The total annual cost is chosen as the objective function. Applying this technique to a case study illustrates its capability to accurate design plate-finned heat exchangers to improve the objective function of the heat exchanger network from the economic viewpoint with the design of details.

Details

Journal of Engineering, Design and Technology , vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 1726-0531

Keywords

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