Numerical Study on Effect of Secondary Surface on Rectangular Vortex Generator

2020 ◽  
Vol 13 (1) ◽  
Author(s):  
Uddip Kashyap ◽  
Koushik Das ◽  
Biplab Kumar Debnath ◽  
Upasana Kashyap ◽  
Sandip K. Saha
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Heated Surface ◽  
Linear Regression Analysis ◽  
Vortex Generator ◽  
Heat Extraction ◽  
Heated Plate ◽  
Primary Vortex ◽  
Reference Case ◽  
Numerical Predictions

Abstract One way of achieving higher efficiency in electro-mechanical is by inducing vortices over the heated surface with the help of a vortex generator (VG). The strength of these vortices is proportionate to the amount of heat transported. In this paper, the evolution and propagation of the produced primary vortex behind a VG with the attached secondary surface (SS) are studied experimentally and numerically. The addition of SS is found to augment heat transfer significantly with an additional drag. The obtained experimental results complement the numerical predictions for the modified VG. Linear regression analysis is performed to optimize the geometry of SS for a higher heat extraction rate and lower drag. The SS placed at an optimum location increases the Nusselt number on the heated plate by 8.9%, with a decrement in the drag by 3.2%, compared to the reference case. The addition of SS produces a vortex of higher strength and propagates downstream at a slower rate. Moreover, it exposes the vortex to higher shear in the flow, which in turn enhances the heat transfer rate.

Numerical and Experimental Study of the Effect of Secondary Surfaces Fixed Over a Rectangular Vortex Generator

2019 ◽  
Vol 11 (6) ◽  
Author(s):  
Uddip Kashyap ◽  
Koushik Das ◽  
Biplab Kumar Debnath
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Heated Surface ◽  
Linear Regression Analysis ◽  
Vortex Generator ◽  
Base Plate ◽  
Constant Heat Flux ◽  
Heated Plate ◽  
Longitudinal Vortices

In order to cool a heated surface surrounded by fluid flow, vortex generator plays a significant role. The presence of a vortex generator in the flow creates both latitudinal and longitudinal vortices. The vortices energize the boundary layer over the heated surface and excel convective mode of heat transfer. Therefore, the strength of these vortices is directly proportional to the heat transferal rate. The present study considers a vortex generator attached to a heated base plate. The system is studied numerically and experimentally. The existing rectangular vortex generator is modified computationally with a goal to escalate the overall heat transferal rate. The role of secondary surfaces fixed over the primary surface of the rectangular vortex generator is discussed. Water flows over the surface of the base plate at a Reynolds number of 350. And the plate has a constant heat flux of 1 kW/m2. The results show that the secondary surfaces fixed parallel to the heated plate over the vortex generator significantly augment the heat transfer rate to about 13.4%. However, it enhances the drag by 5.7%. A linear regression analysis predicts the suitable placement of the secondary surface with an enhancement of heat transfer rate of about 7.6%, with a decrease in the drag by about 0.7%. In order to validate the obtained results, the best configuration is fabricated and tested experimentally. The experimental outcomes are found to complement the numerical results. In this experiment, the modification yields 25% enhancement in heat transfer rate.

Conjugate Heat Transfer From a Heated Disk to a Thin Liquid Film Formed by a Controlled Impinging Jet

1993 ◽  
Vol 115 (1) ◽  
pp. 116-123 ◽  
Author(s):  
A. Faghri ◽  
S. Thomas ◽  
M. M. Rahman
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Conjugate Heat Transfer ◽  
Numerical Study ◽  
Heated Surface ◽  
Thin Liquid Film ◽  
Impinging Jet ◽  
Numerical Predictions ◽  
Heated Disk

An experimental and numerical study of the heat transfer from a heated horizontal disk to a thin film of liquid is described. The liquid was delivered to the disk by a collar arrangement such that the film thickness and radial velocity were known at the outer radius of the collar. This method of delivery is termed as a controlled impinging jet. Flow visualization tests were performed and heat transfer data were collected along the radius of the disk for different volumetric flow rates and inlet temperatures in the supercritical and subcritical regions. The heat transfer coefficient was found to increase with flow rate when both supercritical and subcritical regions were present on the heated surface. A numerical simulation of this free surface problem was performed, which included the effects of conjugate heat transfer within the heated disk and the liquid. The numerical predictions agree with the experimental results and show that conjugate heat transfer has a significant effect on the local wall temperature and heat transfer coefficient.

Multi-Objective Optimization of Laminar Heat Transfer and Friction Factor in Rectangular Microchannel With Rectangular Vortex Generators: An Application of NSGA-II With Gene Expression Programing Metamodel

2017 ◽  
Vol 139 (7) ◽  
Author(s):  
Aparesh Datta ◽  
Ajoy Kumar Das ◽  
Prasenjit Dey ◽  
Dipankar Sanyal
Keyword(s):  
Gene Expression ◽  
Heat Transfer ◽  
Friction Factor ◽  
Numerical Study ◽  
Vortex Generator ◽  
Algorithm Optimization ◽  
Nsga Ii ◽  
Rectangular Microchannel ◽  
Numerical Predictions ◽  
The Cost

Improvement of the effectiveness of heat exchanger is the demand of compact and efficient cooling devices. In that respect, a numerical study of fluid flow and heat transfer has been conducted with different arrangements of simple vortex generator (VG) in a rectangular microchannel Reynolds number (Re) in the range between 200 and 1100. The combined effect of spanwise and pitchwise distance of VG on heat transfer is investigated rigorously to observe the dependence of heat transfer on both. By processing the numerical predictions through gene expression programing and genetic algorithm optimization, the output variations in heat transfer, or Nusselt number, and friction factor with Re and locations of VGs in the channel are predicted in the form of explicit equations. The predicted monotonic increase of the outputs with Re shows heat transfer enhancement of 40–135% at the cost of increased pressure drop by 62–186.7% with respect to channels without VGs.

Experimental and Numerical Study of Methanol-Water Mixture Single-Phase Heat Transfer in a Micro-Channel Heat Sink

2012 ◽  
Author(s):  
Chun K. Kwok ◽  
Matthew M. Asada ◽  
Jonathan R. Mita ◽  
Weilin Qu
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Sink ◽  
Single Phase ◽  
Numerical Study ◽  
Pure Water ◽  
Molar Fraction ◽  
Water Mixture ◽  
Micro Channel ◽  
Numerical Predictions

This paper presents an experimental study of single-phase heat transfer characteristics of binary methanol-water mixtures in a micro-channel heat sink containing an array of 22 microchannels with 240μm × 630μm cross-section. Pure water, pure methanol, and five methanol-water mixtures with methanol molar fraction of 16%, 36%, 50%, 63% and 82% were tested. Key parametric trends were identified and discussed. The experimental study was complemented by a three-dimensional numerical simulation. Numerical predictions and experimental data are in good agreement with a mean absolute error (MAE) of 0.87%.

Numerical Investigation of Heat Transfer Enhancement Using Hybrid Vortex Generator Arrays in Fin-and-Tube Heat Exchangers

2016 ◽  
Vol 8 (3) ◽  
Author(s):  
Shubham Agarwal ◽  
R. P. Sharma
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Heat Transfer Enhancement ◽  
Heat Exchangers ◽  
Numerical Study ◽  
Vortex Generator ◽  
Roll Angle ◽  
Transfer Enhancement ◽  
Maximum Heat ◽  
Hybrid Configuration

This is a novel study for assessing the heat transfer enhancement in a multi-row inline-tube heat exchanger using hybrid vortex generator (VG) arrays, i.e., rectangular winglet pairs (RWPs) with different geometrical configurations installed in coherence for enhanced heat transfer. The three-dimensional numerical study uses a full scale seven-tube inline heat exchanger model. The effect of roll of rectangular winglet VG on heat transfer enhancement is analyzed and optimized roll angle is determined for maximum heat transfer enhancement. Four different configurations are analyzed and compared in this regard: (a) single RWP (no roll); (b) 3RWP-inline array(alternating tube row with no roll of VGs); (c) single RWP (with optimized roll angle VGs); and (d) 3RWP-inline array(alternating tube row with all VGs having optimized roll angle). It was found that the inward roll of VGs increased the heat transfer from the immediately downstream tube but reduced heat transfer enhancement capability of other VG pairs downstream. Further, four different hybrid configurations of VGs were analyzed and the optimum configuration was obtained. For the optimized hybrid configuration at Re = 670, RWP with optimized roll angle increased heat transfer by 17.5% from the tube it was installed on and by 42% from the immediately downstream tube. Increase in j/ƒ of 36.7% is obtained by use of hybrid VGs in the optimized hybrid configuration. The deductions from the current study are supposed to well enhance the performance of heat exchangers with different design configurations.

scholarly journals Numerical Study on Heat Transfer and Flow Characteristics of Pin Fin with Swept Airfoil Shape Vortex Generator

2019 ◽  
Vol 23 (4) ◽  
pp. 28-34
Author(s):  
Changhyeong Lee ◽  
Yeongtaek Oh ◽  
Jihwan Bae ◽  
Deukho Lee ◽  
Kuisoon Kim
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Vortex Generator ◽  
Pin Fin
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