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.

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 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.

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.

Comparison of Natural Convection Heat Transfer from a Vertical Cylinder Fitted with Annular Step Fins and Annular Triangular Fins

2018 ◽  
Vol 10 (5) ◽  
Author(s):  
Shubham Verma ◽  
Harishchandra Thakur
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Convection Heat Transfer ◽  
Vertical Cylinder ◽  
Navier Stokes ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Navier Stokes Equation ◽  
Heat Transfers ◽  
Annular Fins

Natural convection heat transfer from a vertical cylinder with annular step and triangular fins has been studied numerically at various Rayleigh numbers within the laminar range. The computations were carried at constant fin spacing to tube diameter ratio of 1. In the current study, numerical simulations of Navier-Stokes equation supported with the energy equation are conducted for a vertical cylinder with annular step fins as well as triangular annular fins using the algebraic multi-grid solver of Fluent 15. With an increase in Rayleigh number, we’ve discovered a trend that the surface Nusselt number goes on increasing with comparison from a simple rectangular fin. Apart from this, the material needed for the step and triangular fins has been reduced with enhancements in the heat transfers.

Conjugate Natural Convection in Porous Medium With a Thick Square-Wave Partition

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Jayesh Subhash Chordiya ◽  
Ram Vinoy Sharma
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Natural Convection ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Convection Heat Transfer ◽  
Thermal Conductivity Ratio ◽  
Convection Heat ◽  
Square Wave ◽  
Porous Enclosure

Abstract Natural convection within a differentially heated porous enclosure is substantially affected by the presence of partition, fins, or baffles within it. However, not much is known about the effect of partition shape and size. Thus, a solid thick partition in a square-wave shape embedded within a differentially heated porous enclosure has been investigated in this numerical analysis. Through this study, it is sought to contemplate the reduction in the convection heat transfer rate that could be achieved across a differentially heated porous enclosure. The influence of partition thickness, partition amplitude, thermal conductivity ratio, and partition position has been studied. Darcy’s flow model has been solved using the successive accelerated replacement scheme by the finite difference method. One of the findings of this study suggests that lower thermal conductivity of partition, lower partition amplitude, and higher thickness results in a greater reduction in the convection heat transfer rate.

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