Optimal Configuration of Vortex Generator for Heat Transfer Enhancement in a Plate-Fin Channel

2017 ◽  
Vol 10 (2) ◽  
Author(s):  
Tariq Amin Khan ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Numerical Simulations ◽  
Three Dimensional ◽  
Vortex Generator ◽  
Design Parameters ◽  
Heat Transfer Characteristics ◽  
Maximum Heat ◽  
Transfer Characteristics ◽  
Maximum Heat Transfer ◽  
Independent Design

Heat transfer is a naturally occurring phenomenon and its augmentation is a vital research topic for many years. Although, vortex generators (VGs) are widely used to enhance the heat transfer of plate-fin type heat exchangers, few researches deal with its thermal optimization. This work is dedicated to the numerical investigation and optimization of VGs configuration in a plate-fin channel. Three-dimensional (3D) numerical simulations are performed to study the effect of angle of attack and attach angle (angle between VG and wall) and shape of VG on the fluid flow and heat transfer characteristics. The flow is assumed as steady-state, incompressible, and laminar within the range of studied Reynolds numbers (Re = 380–1140). Results are presented in the form average and local Nusselt number and friction factor. The effect of attach angle is highlighted and the results show that the attach angle of 90 deg may not be necessary for enhancing the heat transfer. The flow structure and heat transfer characteristics of certain cases are examined in detail. The parameters of VG are then optimized for maximum heat transfer and minimum pressure drop. The three independent design parameters are considered for the two objective functions. For this purpose, computation fluid dynamics (CFD) data, response surface methodology (RSM) and a multi-objective optimization algorithm (MOA) are combined. The data obtained from numerical simulations are used to train a Bayesian-regularized artificial neural network (BRANN). This in turn is used to drive a MOA to find the optimal parameters of VGs in the form of Pareto front. The optimal values of these parameters are finally presented.

Local Heat Transfer Characteristics in Simulated Electronic Modules

2003 ◽  
Vol 125 (3) ◽  
pp. 362-368 ◽  
Author(s):  
Seong-Yeon Yoo ◽  
Jong-Hark Park ◽  
Min-Ho Chung
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Three Dimensional ◽  
Vortex Generator ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Two Dimensional ◽  
Heat Transfer Characteristics ◽  
Dimensional Array ◽  
Transfer Characteristics

When heat is released by forced convection from electronic modules in a narrow printed circuit board channel, complex flow phenomena—such as stagnation and acceleration on the front surface, separation and reattachment on the top surface, wake or cavity flow near the rear surface—affect the heat transfer characteristics. The purpose of this study is to investigate how these flow conditions influence the local heat transfer from electronic modules. Experiments are performed on a three-dimensional array of hexahedral elements as well as on a two-dimensional array of rectangular elements. Naphthalene sublimation technique is employed to measure three-dimensional local mass transfer, and the mass transfer data are converted to their counterparts of the heat transfer process using the analogy equation between heat and mass transfer. Module location and streamwise module spacing are varied, and the effect of vortex generators on heat transfer enhancement is also examined. Dramatic change of local heat transfer coefficients is found on each surface of the module, and three-dimensional modules have a little higher heat transfer value than two-dimensional modules because of bypass flow. Longitudinal vortices formed by vortex generator enhance the mixing of fluids and thereby heat transfer, and the rectangular wing type vortex generator is found to be more effective than the delta wing type vortex generator.

scholarly journals Flow and heat transfer characteristics downstream of a porous sudden expansion: A numerical study

2011 ◽  
Vol 15 (2) ◽  
pp. 389-396 ◽  
Author(s):  
Khalid Alammar
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Darcy Number ◽  
Sudden Expansion ◽  
Heat Transfer Characteristics ◽  
Maximum Heat ◽  
Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Maximum Heat Transfer ◽  
Inertia Coefficient

Incompressible, axisymmetric laminar flow downstream of a porous expansion is simulated. Effect of the Darcy number and inertia coefficient on flow and heat transfer characteristics downstream of the expansion is investigated. The simulation revealed circulation downstream of the expansion. Decreasing the Darcy number is shown to decrease the circulation region. The Nusselt number, friction coefficient, and pressure drop are shown to increase, while reattachment and location of maximum heat transfer move upstream with decreasing Darcy number. Similar effects are observed with increasing inertia coefficient.

scholarly journals OPTIMALLY STAGGERED FINNED CIRCULAR AND ELLIPTIC TUBES IN FORCED CONVECTION

2003 ◽  
Vol 2 (2) ◽  
pp. 65 ◽  
Author(s):  
R. S. Matos ◽  
T. A. Laursen ◽  
J. V. C. Vargas ◽  
A. Bejan
Keyword(s):  
Heat Transfer ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
Total Heat ◽  
Cross Sectional ◽  
Maximum Heat ◽  
Pressure Drops ◽  
Tube Cross Section ◽  
Fixed Volume ◽  
Maximum Heat Transfer

This work presents a three-dimensional (3-D) numerical and experimental geometric optimization study to maximize the total heat transfer rate between a bundle of finned tubes in a given volume and a given external flow both for circular and elliptic arrangements, for general staggered configurations. The optimization procedure started by recognizing the design limited space availability as a fixed volume constraint. The experimental results were obtained for circular and elliptic configurations with a fixed number of tubes (12), starting with an equilateral triangle configuration, which fitted uniformly into the fixed volume with a resulting maximum dimensionless tube-to-tube spacing S/2b = 1.5, where S is the actual spacing and b is the smaller ellipse semi-axis. Several experimental configurations were built by reducing the tube-to-tube spacings, identifying the optimal spacing for maximum heat transfer. Similarly, it was possible to investigate the existence of optima with respect to other two geometric degrees of freedom, i.e., tube eccentricity and fin-to-fin spacing. The results are reported for air as the external fluid in the laminar regime, for 125 and 100 Re 2b , where 2b is the ellipses smaller axis length. Circular and elliptic arrangements with the same flow obstruction cross-sectional area were compared on the basis of maximum total heat transfer. This criterion allows one to quantify the heat transfer gain in the most isolated way possible, by studying arrangements with equivalent total pressure drops independently of the tube cross section shape. This paper reports three-dimensional (3- D) numerical optimization results for finned circular and elliptic tubes arrangements, which are validated by direct comparison with experimental measurements with good agreement. Global optima with respect to tube-to-tube spacing, eccentricity and fin-tofin spacing ( 0.5 e 0.5, S/2b and 06 . 0 f for 125 and 100 Re 2b , respectively) were found and reported in general dimensionless variables. A relative heat transfer gain of up to 19% is observed in the optimal elliptic arrangement, as compared to the optimal circular one. The heat transfer gain, combined with the relative material mass reduction of up to 32% observed in the optimal elliptic arrangement in comparison to the circular one, show the elliptical arrangement has the potential for a considerably better overall performance and lower cost than the traditional circular geometry.

Parametric Analysis of a Bayonet Tube With a Special Type of Extended Surface

2010 ◽  
Author(s):  
L. Almanza-Huerta ◽  
A. Hernandez-Guerrero ◽  
M. Krarti ◽  
J. M. Luna
Keyword(s):  
Heat Transfer ◽  
Parametric Analysis ◽  
Numerical Study ◽  
Systematic Investigation ◽  
Heat Transfer Characteristics ◽  
Maximum Heat ◽  
Turbulent Transition ◽  
Maximum Heat Transfer ◽  
Internal Fluid ◽  
Extended Surface

The present paper provides a numerical study of a parametric analysis of a bayonet tube with a special type of extended surface during the laminar-turbulent transition. The working internal fluid is air. Attention is focused on the heat transfer characteristics of the tube. The results constitute a systematic investigation of the effect of the extended surface located along the annulus of the bayonet on the overall heat transfer rate. The effects of the variation of some parameters related to the extended surface aiming to attain the maximum heat transfer with the minimum pressure drop are discussed. Comparisons between designs with and without extended surface are also made.

Pressure Drop and Heat Transfer Characteristics of Louvered Fin Heat Exchangers

2013 ◽  
Vol 465-466 ◽  
pp. 500-504 ◽  
Author(s):  
Shahrin Hisham Amirnordin ◽  
Hissein Didane Djamal ◽  
Mohd Norani Mansor ◽  
Amir Khalid ◽  
Md Seri Suzairin ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Heat Transfer Rate ◽  
Heat Exchangers ◽  
Transfer Rate ◽  
Three Dimensional ◽  
Considerable Effect ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Louvered Fin

This paper presents the effect of the changes in fin geometry on pressure drop and heat transfer characteristics of louvered fin heat exchanger numerically. Three dimensional simulation using ANSYS Fluent have been conducted for six different configurations at Reynolds number ranging from 200 to 1000 based on louver pitch. The performance of this system has been evaluated by calculating pressure drop and heat transfer coefficient. The result shows that, the fin pitch and the louver pitch have a very considerable effect on pressure drop as well as heat transfer rate. It is observed that increasing the fin pitch will relatively result in an increase in heat transfer rate but at the same time, the pressure drop will decrease. On the other hand, low pressure drop and low heat transfer rate will be obtained when the louver pitch is increased. Final result shows a good agreement between experimental and numerical results of the louvered fin which is about 12%. This indicates the capability of louvered fin in enhancing the performance of heat exchangers.

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