Numerical Studies on Natural Convection Heat Transfer – Fins with Closed Top

2014 ◽  
Vol 592-594 ◽  
pp. 1682-1686 ◽  
Author(s):  
C. Balachandar ◽  
S. Arunkumar ◽  
M. Venkatesan
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Base Plate ◽  
Plate Temperature ◽  
Ansys Fluent ◽  
Numerical Studies ◽  
Vertical Base

Fins are extended surfaces provided to enhance the heat transfer rate of a system. Several attempts have been made in the past to augment the heat transfer rate by using fins of various geometries. In the present study an array of rectangular fins with closed top, standing on a vertical base is analysed under natural convection conditions using commercial CFD code ANSYS FLUENT©. The numerical model is validated with the available experimental results for fins with open top under natural convection conditions. The plate fin heat sink is analysed for a constant heat duty of 60 W. The height, thickness and length of the fins are taken to be constant throughout the analysis. A detailed study is carried out to examine the dependency of the base plate temperature on the thickness of the closed top and on the number of fins. It is concluded based on the analysis that heat fins with closed top are found to have a decreased base plate temperature compared to the conventional rectangular fins.

scholarly journals Numerical Analysis Natural Convection Heat Transfer from Vertical Cylinder Annular Fins with The Addition of Slits

2021 ◽  
Vol 9 (4) ◽  
pp. 405-409
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Vertical Cylinder ◽  
Simulation Method ◽  
Cylinder Length ◽  
Annular Fin ◽  
Annular Fins

One method of increasing the heat transfer rate of the fins is by adding slits to the fins. The purpose of this study was to analyze the heat transfer rate by adding slits in the annular fins with a vertical cylinder under natural convection conditions. The vertical cylinder length, cylinder diameter, fin diameter, and distance between the fins are 313 mm, 25 mm, 125 mm, and 7 mm, respectively. The number of slits varied from 2 slits and 4 slits and the spacing of the slits was kept constant by 5 mm. This research was conducted with a simulation method using Autodesk CFD 2019 software. As a result, fins with slits and fins without slits were compared. The value of the heat transfer rate that occurs and the heat transfer coefficient in the annular fin with slits is better than the fin without slits. The highest heat transfer rates were 142.928 W and 2.6022 W/m 2K for an annular fin with 2 slits

scholarly journals Effect of Fin Number and Position on Non-linear Characteristics of Natural Convection Heat Transfer in Internally Finned Horizontal Annulus

2021 ◽  
Vol 9 ◽  
Author(s):  
Kun Zhang ◽  
Yu Zhang ◽  
Xiaoyu Wang ◽  
Liangbi Wang
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Stokes Equations ◽  
Convection Heat Transfer ◽  
The Self ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Simpler Algorithm

Detailed numerical calculations are performed for investigating the effect of fin number and position on unsteady natural convection heat transfer in internally finned horizontal annulus. The SIMPLER algorithm with Quick scheme is applied for solving the Navier Stokes equations of flow and heat transfer. The results show that the heat transfer rate in annulus with fins increases with the increasing numbers of fin and Rayleigh numbers. For Ra = 2 × 105, the effect of numbers of fins and fins position at the bottom part on the unsteady solutions can be neglected, because the self-oscillation phenomenon is mainly affected by natural convection at the upper part of annulus. Although the fin positions cannot increase heat transfer rate significantly in the case of four fins, the self-oscillated solutions can be suppressed by altering fins position.

scholarly journals Natural Convection in a Differentially Heated Square Enclosure with a Solid Polygon

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
R. Roslan ◽  
H. Saleh ◽  
I. Hashim
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Critical Size ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Thermal Conductivity Ratio ◽  
Left Wall ◽  
Square Enclosure

The aim of the present numerical study is to analyze the conjugate natural convection heat transfer in a differentially heated square enclosure containing a conductive polygon object. The left wall is heated and the right wall is cooled, while the horizontal walls are kept adiabatic. The COMSOL Multiphysics software is applied to solve the dimensionless governing equations. The governing parameters considered are the polygon type,3≤N≤∞, the horizontal position,0.25≤X0≤0.75, the polygon size,0≤A≤π/16, the thermal conductivity ratio,0.1≤Kr≤10.0, and the Rayleigh number,103≤Ra≤106. The critical size of the solid polygon was found exists at low conductivities. The heat transfer rate increases with the increase of the size of the solid polygon, until it reaches its maximum value. Here, the size of the solid polygon is reaches its critical value. Further, beyond this critical size of the solid polygon, will decrease the heat transfer rate.

3D natural convection on a horizontal and vertical thermally active plate in a closed cubical cavity

2016 ◽  
Vol 26 (8) ◽  
pp. 2528-2542 ◽  
Author(s):  
Abimanyu Purusothaman ◽  
Abderrahmane Baïri ◽  
Nagarajan Nithyadevi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Numerical Code ◽  
Heated Plate ◽  
Algebraic Equations ◽  
Content Type ◽  
Cubical Cavity

Purpose The purpose of this paper is to examine numerically the natural convection heat transfer in a cubical cavity induced by a thermally active plate. Effects of the plate size and its orientation with respect to the gravity vector on the convective heat transfer and the flow structures inside the cavity are studied and highlighted. Design/methodology/approach The numerical code is based on the finite volume method with semi-implicit method for pressure-linked equation algorithm. The convective and diffusive terms in momentum equations are handled by adopting the power law scheme. Finally, the discretized sets of algebraic equations are solved by the line-by-line tri-diagonal matrix algorithm. Findings The results show that plate orientation and size plays a significant role on heat transfer. Also, the heat transfer rate is an increasing function of Rayleigh number for both orientations of the heated plate. Depending on the thermal management of the plate and its application (as in electronics), the heat transfer rate is maximized or minimized by selecting appropriate parameters. Research limitations/implications The flow is assumed to be 3D, time-dependent, laminar and incompressible with negligible viscous dissipation and radiation. The fluid properties are assumed to be constant, except for the density in the buoyancy term that follows the Boussinesq approximation. Originality/value The present work will give some additional knowledge in designing sealed cavities encountered in some engineering applications as in aeronautics, automobile, metallurgy or electronics.

scholarly journals Enhancement of natural convection heat transfer in concentric annular space using inclined elliptical cylinder

2020 ◽  
Vol 17 (2) ◽  
pp. 89-99
Author(s):  
Houssem Laidoudi
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Aspect Ratio ◽  
Heat Transfer Rate ◽  
Inclination Angle ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Elliptical Cross

The governing equations of continuity, momentum and energy are numerically solved to study the laminar natural convection heat transfer of Newtonian fluid confined within two concentric cylinders. The inner cylinder is elliptical cross-section with different aspect ratio E = 0.1 to 0.5 and it is considered to be hot, whereas the outer cylinder is circular and it is supposed to be cold.    The annular spacing between the cylinders is defined based on radii ratio (RR = 2.5). Also, the inner cylinder is inclined with an inclination angle (θ = 0 to 90). The main purpose of this study is to determine the effects of inclination angle (θ = 0° to 90°), aspect ratio of inner cylinder (E = 0.1 to 0.5), Prandtl number (Pr = 0.71 and 7.01) and Rayleigh number (Ra = 103 to 105) on fluid flow and heat transfer rate. The flow patterns and temperature distributions are potted in terms of streamlines and isotherms respectively. The obtained results showed that increase in inclination angle enhances the heat transfer rate of inner cylinder for all values of aspect ratio. Also, for the inclination angle          (θ = 90°), the decrease in aspect ratio (E) improves the heat transfer rate of inner cylinder.

Enhancement of Natural Convection Heat Transfer Rate in Internal Compressible Flows by Inserting Stationary Inserts

2008 ◽  
Author(s):  
Emad Y. Tanbour ◽  
Ramin K. Rahmani
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Enhancement ◽  
Compressible Flow ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Transfer Enhancement ◽  
Stationary Heat Transfer

Enhancement of the natural and forced convection heat transfer has been the subject of numerous academic and industrial studies. Air blenders, mechanical agitators, and static mixers have been developed to increase the forced convection heat transfer rate in compressible and incompressible flows. Stationary inserts can be efficiently employed as heat transfer enhancement device in the natural convection systems with compressible flow. Generally, a stationary heat transfer enhancement insert consists of a number of equal motionless units, placed on the inside of a pipe or channel in order to control flowing fluid streams. These devices have low maintenance and operating costs, low space requirements and no moving parts. A range of designs exists for a wide range of specific applications. The shape of the elements determines the character of the fluid motion and thus determines thermal effectiveness of the insert. There are several key parameters that may be considered in the design procedure of a heat transfer enhancement insert, which lead to significant differences in the performance of various designs. An ideal insert for natural conventional heat transfer of compressible flow applications provides a higher rate of heat transfer and a thermally homogenous fluid with minimized pressure drop and required space. To choose an insert for a given application or in order to design a new insert, besides experimentation, it is possible to use computational fluid dynamics (CFD) tools to study insert performance. This paper presents the outcomes of the numerical studies by the authors on an industrial stationary heat transfer enhancement insert and illustrates how a heat transfer enhancement insert can improve the heat transfer in a buoyancy driven compressible flow. The numerical predictions were validated using experimental data. Using different measuring tools, the global performance of the insert and the impact of the geometrical parameters are studied in order to choose the most effective design for a given application.

scholarly journals Natural Convection Heat Transfer From Arrays of Isothermal Triangular Fins in Air

1994 ◽  
Vol 116 (1) ◽  
pp. 105-111 ◽  
Author(s):  
A. Karagiozis ◽  
G. D. Raithby ◽  
K. G. T. Hollands
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Heat Transfer Performance ◽  
Large Range ◽  
Convection Heat Transfer ◽  
Base Plate ◽  
Single Equation ◽  
Vertical Orientation ◽  
Nusselt Numbers ◽  
Vertical Base

Measurements of the heat transfer to air by natural convection from arrays of isothermal triangular fins on a vertical base plate are reported for several array geometries, for a large range of Rayleigh number, and for two orientations (vertical fins and horizontal fins). The data are believed to be the first available for this important geometry. A single equation is provided that correlates the measured Nusselt numbers for the vertical orientation with an rms error of 4.8 percent. The horizontal fin orientation was shown to have inferior heat transfer performance.

scholarly journals Heat Transfer by Natural Convection through V-Corrugated Plates

1970 ◽  
Vol 36 ◽  
pp. 1-5
Author(s):  
Mohammad Ali ◽  
M Hasanuzzaman
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Mass Flow Rate ◽  
Heat Transfer Rate ◽  
Flow Rate ◽  
Transfer Rate ◽  
Inlet Temperature ◽  
Cold Plate ◽  
Plate Temperature ◽  
Square Enclosure

An experimental investigation is performed on natural convection heat transfer through a square enclosure of V-corrugated vertical plates. The objective of this investigation is to study the variation of heat transfer rate through the square enclosure with the variation of both hot and cold plate temperatures. Hot plate temperature is varied by heat input. To vary cold plate temperature two parameters are considered: one is mass flow rate of water used to remove heat from cold plate and the other is the inlet temperature of water. Air is the media to transfer heat from the hot V-corrugated plate to cold V-corrugated plate. The result shows that the increase of mass flow rate increases the heat transfer rate and the decrease of water inlet temperature increases the heat transfer rate.Journal of Mechanical Engineering Vol.36 Dec. 2006 pp.1-5DOI = 10.3329/jme.v36i0.804

Natural Convection Heat Transfer With Horizontal Rectangular Fin Array Using Straight Knurling Patterns on Fins: An Experimental Study

2018 ◽  
Author(s):  
R. C. Chikurde ◽  
B. S. Kothavale ◽  
N. K. Sane
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Flow Characteristics ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Heat Transfer Augmentation

Natural Convection heat transfer from horizontal rectangular fin array with various knurling patterns is studied experimentally to find the effect of varying surface roughness on the heat transfer rate. The experimental parametric study is performed to investigate the effect of knurl produced surface roughness of fin on heat transfer rate. The parameters like knurling height from base, knurling depth and fin spacing might affect the flow characteristics and hence it is investigated to find the effect on heat transfer coefficient. The knurling is usually accomplished using one or more very hard rollers that contain the reverse of the pattern to be imposed. The result of this study shows that there are some important geometric factors related to knurling affecting the design of fin arrays and also heat transfer augmentation of natural convection heat transfer is observed.

Numerical Analysis on Hollow Cylindrical Pin Fins - Natural Convection

2015 ◽  
Vol 813-814 ◽  
pp. 713-717
Author(s):  
E. Shreehari ◽  
S. Sanjay ◽  
M. Venkatesan
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Hot Spots ◽  
Base Plate ◽  
Internal Diameter ◽  
Outer Diameter ◽  
Plate Temperature ◽  
Ansys Fluent ◽  
Pin Fins ◽  
Extended Surface

In most of the engineering applications unnecessary heat is produced. Fins are extended surface which are used to enhance heat transfer rate from a surface by increasing the area exposed to convection. The addition of fin increases the surface area and this forms an economical solution for increasing the efficiency and the performance of the device. In the present study a comparative analysis is made between an array of hollow pin fins in upward facing and sideward facing arrangement under natural convection. The model is numerically investigated using commercial CFD code ANSYS FLUENT©. The fin outer diameter (12mm) and fin height (50mm) are kept constant. The parameters varied are the internal diameter of the fins and the heat laod. The results show that the sideward fins have lower base plate temperature as expected due to buoyancy effects. However hot spots are identified in the case of sideward facing fins which will affect the heat transfer characteristics when compared to upward facing hollow cylindrical pin fins.

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