Heat Transfer Analysis Of Nano-fluid Flow In A Converging Nozzle With Different Aspect Ratios

2017 ◽  
Vol 20 (4) ◽  
pp. 161-167 ◽  
Author(s):  
T. Sathish
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Aspect Ratio ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Heat Transfer Analysis ◽  
Element Analysis ◽  
Frictional Loss ◽  
Nano Fluid ◽  
Aspect Ratios

The study evaluates the nanofluid using finite element analysis with base fluid (water) and seeding particles (Aluminum oxide). This is placed over a convergence channel consisting of varying aspect ratio that are evaluated quantitatively to enhance the heat transfer properties of the nanofluid.We have considered frictional loss characteristics that increases the flow of the fluid with Reynolds numbers varying from 100-2000 is compared.A baseline modeling is established using the methodology analysis for the fluid flow over a rectangular chamber that is designed in the form of a square duct of ratio 1:1. The analysis is carried out over the heat transfer and flow rate characteristics of the nanofluid that converges into the square ducts with different aspect ratio, is analyzed.The concentration of the nano fluid is maintained at the constant rate, which is used for studying the flow rate influence over different aspect ratios. The thermal and flow characteristics is analyzed in such situation and validated against other literatures to check the efficiency in the converging rectangular oxygen free copper channel.The simulation results shows an increase in temperature on the duct out and drop in temperature on the inlet walls of the tube.The pressure changes and shear stress along the walls of the chamber is not much noticed and it is constant throughout the entire chamber.

Numerical study on significance of wave amplitude, wavelength and aspect ratio on heat transfer and fluid flow characteristics in circular wavy MC heat sink design

2021 ◽  
pp. 095440622198937
Author(s):  
Valaparla Ranjith Kumar ◽  
Karthik Balasubramanian ◽  
K Kiran Kumar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fluid Flow ◽  
Aspect Ratio ◽  
Wave Amplitude ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Uniform Heat Flux ◽  
Uniform Heat ◽  
Fluid Flow Characteristics

In this study, hydrothermal characteristics in a circular wavy microchannel (CWMC) design under laminar flow conditions with uniform heat flux is numerically studied. Parametric studies in an innovative CWMC design were carried out at various wave amplitudes, wavelengths and aspect ratios. Three dimensional numerical study was performed in the Reynolds number (Re) range from 100 to 300 with uniform heat flux (50 W/cm2) applied at bottom of the channel, treating copper as channel material and water as working fluid. The obtained results were compared to sinusoidal wavy microchannel (SWMC).The results showed that heat transfer and fluid flow characteristics were significantly influenced by wave amplitude, wavelength and aspect ratio. Velocity vectors and contours were presented to understand the heat transfer and fluid flow characteristics. Stream-wise local Nusselt number, overall performance factor, span-wise velocity and temperature variation are also presented. It is concluded that CWMC with higher wave amplitude, smaller wave length and smaller aspect ratio gives higher heat transfer augmentation with corresponding pressure drop penalty.

Heat Transfer Analysis of Turbulent Flow in Rectangular-Sectioned U-Bends

2004 ◽  
Author(s):  
Sassan Etemad ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Aspect Ratio ◽  
Turbulent Flow ◽  
Secondary Flow ◽  
Cross Section ◽  
Heat Transfer Analysis ◽  
Reference Case ◽  
Aspect Ratios ◽  
The Impact

The turbulent flow in rectangular-sectioned U-bend ducts with bend mid-line radius 3.35 and with aspect-ratios AR=0.5, 1, 2, and 4 were explored using linear and non-linear high- and low-Re k-ε turbulence models at a Reynolds number of 56000. The impact of the cross-section aspect ratio on the flow field and the associated thermal field was studied. Experimental data were found [1–3] for the square-sectioned cross section (AR=1) and this case was chosen as the reference case for comparison and validation with experimental data. The other cases were evaluated in relation to the square-sectioned case. The predicted data for AR=1 agreed well with the experimental data. The velocity profile upstream the bend has fundamental influence on the strength of the secondary flow and heat transfer. Complex secondary motion was detected for all cases but in particular for AR=1. The mixing process due to the secondary flow decreased in general with increasing aspect ratio.

Numerical Study on Effect of Volume Fraction of Nanoparticles on Rayleigh-Bernard Convection in Different Enclosures

2014 ◽  
Vol 592-594 ◽  
pp. 945-950 ◽  
Author(s):  
S. Senthil Kumar ◽  
S. Karthikeyan
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Volume Fraction ◽  
Numerical Study ◽  
Flow Characteristics ◽  
Boussinesq Approximation ◽  
Working Fluid ◽  
Volume Fractions ◽  
Aspect Ratios ◽  
Fluid Flow Characteristics

Numerical investigations of Rayleigh-Bernard convection in enclosures of different modified bottom and top surfaces filled with Au-Water Nanofluid with different volume fractions are presented. This paper describes a numerical predication of heat transfer and fluid flow characteristics inside enclosures bounded by modified bottom and top surfaces and two periodic straight vertical walls. Simulations are carried out for a Rayleigh number of 6×104 and two aspect ratios (0.25 & 0.5) with working fluid as Au-Water Nanofluid and The same analyses are performed with the Nanofluid having Au nanoparticles of same size and different volume fraction of φ = 5%, 10%, 15% and 20 % in order to see the effect of Nanofluid volume fraction on heat transfer. The Boussinesq approximation is used in order to take density change effect in the governing equations. The study investigates the effect of the nanoparticles volume fraction, and the aspect ratio on the heat transfer. The results are presented in terms of isotherms, streamlines local and average surface Nusselt numbers. Results show that the flow and isotherms are affected by the geometry shape and by the presence of nanoparticles with different volume fractions. It is also shown that for a fixed value of aspect ratio, the convective heat transfer is decreased for the increase in volume fraction of Nanofluid.

Scaling of Flow Characteristics and Power Consumption With Profile Height for Miniature Centrifugal Fans

2007 ◽  
Author(s):  
P. A. Walsh ◽  
V. Egan ◽  
R. Grimes ◽  
E. Walsh
Keyword(s):  
Aspect Ratio ◽  
Power Consumption ◽  
Flow Rate ◽  
Scaling Laws ◽  
Flow Characteristics ◽  
Pressure Rise ◽  
Maximum Flow ◽  
Aspect Ratios ◽  
Low Profile ◽  
Centrifugal Fans

This paper addresses issues that relate to downscaling the height of centrifugal fans for application in low profile technologies, such as the cooling of portable power electronics. The parameters studied throughout the paper include flow rate, pressure rise and power consumption characteristics. The former two of these are measured using a fan characterization rig and the latter by directly measuring the power supplied to the fan. These are studied for fans ranging in diameter from 15 to 30mm and with profile heights ranging from 0.3mm to 15mm. It is found that all of the phenomena encountered are best described in terms of fan aspect ratio. Overall, the results show that the conventional scaling laws cannot be accurately applied when the blade profile alone is being scaled. Indeed the only parameter that was observed to be accurately predicted by the scaling laws was the pressure rise attainable but was only accurate for fan aspect ratios greater than 0.17. Below this, the measured pressure rise characteristics fell logarithmically toward zero. The results also showed that there is no advantage to using fans with aspect ratio greater than 0.3. This was because the maximum flow rate was achieved at this aspect ratio and decreased slightly as it was further increased. Overall, the scaling phenomena described throughout this paper are invaluable to designer of efficient low profile cooling solutions that are to incorporate such fans.

Heat Transfer for High Aspect Ratio Rectangular Channels in a Stationary Serpentine Passage With Turbulated and Smooth Surfaces

2013 ◽  
Author(s):  
Matthew A. Smith ◽  
Randall M. Mathison ◽  
Michael G. Dunn
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Aspect Ratio ◽  
Flow Behavior ◽  
Reynolds Numbers ◽  
Hydraulic Diameter ◽  
Internal Cooling ◽  
Number Range ◽  
Aspect Ratios ◽  
Parallel Configuration

Heat transfer distributions are presented for a stationary three passage serpentine internal cooling channel for a range of engine representative Reynolds numbers. The spacing between the sidewalls of the serpentine passage is fixed and the aspect ratio (AR) is adjusted to 1:1, 1:2, and 1:6 by changing the distance between the top and bottom walls. Data are presented for aspect ratios of 1:1 and 1:6 for smooth passage walls and for aspect ratios of 1:1, 1:2, and 1:6 for passages with two surfaces turbulated. For the turbulated cases, turbulators skewed 45° to the flow are installed on the top and bottom walls. The square turbulators are arranged in an offset parallel configuration with a fixed rib pitch-to-height ratio (P/e) of 10 and a rib height-to-hydraulic diameter ratio (e/Dh) range of 0.100 to 0.058 for AR 1:1 to 1:6, respectively. The experiments span a Reynolds number range of 4,000 to 130,000 based on the passage hydraulic diameter. While this experiment utilizes a basic layout similar to previous research, it is the first to run an aspect ratio as large as 1:6, and it also pushes the Reynolds number to higher values than were previously available for the 1:2 aspect ratio. The results demonstrate that while the normalized Nusselt number for the AR 1:2 configuration changes linearly with Reynolds number up to 130,000, there is a significant change in flow behavior between Re = 25,000 and Re = 50,000 for the aspect ratio 1:6 case. This suggests that while it may be possible to interpolate between points for different flow conditions, each geometric configuration must be investigated independently. The results show the highest heat transfer and the greatest heat transfer enhancement are obtained with the AR 1:6 configuration due to greater secondary flow development for both the smooth and turbulated cases. This enhancement was particularly notable for the AR 1:6 case for Reynolds numbers at or above 50,000.

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