A Parametric Numerical Study in Cylindrical Oblique Fin Minichannel

2013 ◽  
Author(s):  
Yan Fan ◽  
Poh Seng Lee ◽  
Li-Wen Jin ◽  
Beng Wah Chua ◽  
Na-Si Mou ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Sink ◽  
Numerical Study ◽  
Three Dimensional ◽  
Numerical Data ◽  
Channel Structure ◽  
Heat Sinks ◽  
Secondary Channel ◽  
Oblique Angle

A novel cylindrical oblique fin minichannel heat sink was proposed to cool cylindrical heat sources using forced convection scheme. In this paper, parametric numerical study was employed to understand the importance of the various dimensions of the oblique fin heat sinks and their heat transfer performance and pressure drop. Three dimensional conjugated heat transfer simulations were carried out using Computational Fluid Dynamics (CFD) method based on laminar flow to determine its performance in the oblique fin heat sink. 214 parametric studies were performed by varying the oblique angle from 20° to 45°, secondary channel gap from 1mm to 5mm and Reynolds number from 200 to 900. Their thermal performance was compared for a constant heat flux of 1 W/cm2. The results show that the flow is main channel directed in shorter secondary channel structure while the flow becomes secondary channel directed in longer secondary channel structure. Secondary flow becomes more effective in heat transfer when increasing the secondary channel gap. When the oblique angle increases, more flow will be diverted into secondary channel and improve flow mixing to enhance the heat transfer. The best configuration in this paper was suggested based on the numerical data point. The overall performance can be improved up to 110% at Reynolds number of 900 compared with conventional straight fin minichannel. Therefore, this is the attractive candidate for future cylindrical heat sinks.

Three-Dimensional Analysis of Fluid Flow and Heat Transfer in Single- and Two-Layered Micro-Channel Heat Sinks

2008 ◽  
Author(s):  
M. L.-J. Levac ◽  
H. M. Soliman ◽  
S. J. Ormiston
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Numerical Study ◽  
Three Dimensional ◽  
Heat Sinks ◽  
Micro Channel ◽  
Flow Conditions ◽  
Flow And Heat Transfer ◽  
Computer Chips ◽  
Laminar Flow Conditions

Micro-channel heat sinks are currently at the forefront of cooling technologies for computer chips where the input heat flux is projected to exceed 100 W/cm2 [1, 2]. The quest for better heat-sink designs has produced different ideas, one of which is the idea of using multi-layered micro-channel heat sinks [3, 4]. The objectives of the present investigation were to conduct a detailed numerical study of the hydrodynamic and thermal behavior of a two-layered micro-channel heat sink and to compare the performance of the two-layered heat sink with that of a single-layered sink under laminar flow conditions.

Impinging Jet Cooled Plate Fin Heat Sinks With Turbulators Enhancement

2009 ◽  
Author(s):  
Ganesh Subbuswamy ◽  
Xianchang Li
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Heat Sink ◽  
Numerical Study ◽  
Turbine Blades ◽  
Jet Impingement ◽  
Impinging Jet ◽  
Impinging Jets ◽  
Heat Sinks ◽  
Internal Cooling

Extended surfaces (fins) and impinging jets have been used to enhance heat transfer in many applications. In electronic thermal management, heat sinks can be designed to take advantage of the combined effect of fins and jet impingement such as jets impinging on an array of pin fins or plate fins. Significant studies have been focused on the thermal resistance, pressure drop, and the parametric effect of Reynolds number, fin thickness, density, and height. To further improve the heat sink performance, ribs/turbulators, which are widely employed in internal cooling of gas turbine blades, can be integrated into the plate fins, especially close to the surface area with low heat transfer coefficient. Numerical study is performed in this paper to examine the flow and heat transfer behavior of plate fin heat sinks cooled by an impinging jet and enhanced by the ribs. The height and shape of the turbulators are investigated to achieve the best performance. Parametric studies also include the flow Reynolds number and the spacing between the ribs. Heat transfer mechanism is explored for the confined turbulence jet with and without turbulators. It is expected that the rib enhancement can lead to a more cost-effective heat sink for cooling of electronic components. Further enhancement and optimization are discussed in this paper.

Fluid Flow and Heat Transfer of Liquid Sodium in Small-Scale Heat Sinks With Different Geometries

2021 ◽  
Author(s):  
Mahyar Pourghasemi ◽  
Nima Fathi
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Cross Sections ◽  
Heat Sink ◽  
Volume Ratio ◽  
Heat Sinks ◽  
Liquid Sodium ◽  
Small Scale ◽  
Nusselt Numbers ◽  
The Difference

Abstract 3-D numerical simulations are performed to investigate liquid sodium (Na) flow and the heat transfer within miniature heat sinks with different geometries and hydraulic diameters of less than 5 mm. Two different straight small-scale heat sinks with rectangular and triangular cross-sections are studied in the laminar flow with the Reynolds number up to 1900. The local and average Nusselt numbers are obtained and compared against eachother. At the same surface area to volume ratio, rectangular minichannel heat sink leads to almost 280% higher convective heat transfer rate in comparison with triangular heat sink. It is observed that the difference between thermal efficiencies of rectangular and triangular minichannel heat sinks was independent of flow Reynolds number.

Pin-Fin Heat Sink With Horizontal Base and Blocked Edges

2008 ◽  
Author(s):  
D. Sahray ◽  
H. Shmueli ◽  
N. Segal ◽  
G. Ziskind ◽  
R. Letan
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Contact Resistance ◽  
Cross Section ◽  
Heat Input ◽  
Heat Sink ◽  
Numerical Study ◽  
Heat Sinks ◽  
Transfer Enhancement ◽  
Pin Fin

In the present work, horizontal-base pin fin heat sinks exposed to free convection in air are studied. They are made of aluminum, and there is no contact resistance between the base and the fins. For the same base dimensions the fin height and pitch vary. The fins have a constant square cross-section. The edges of the sink are blocked: the surrounding insulation is flush with the fin tips. The effect of fin height and pitch on the performance of the sink is studied experimentally and numerically. In the experiments, the heat sinks are heated using foil electrical heaters. The heat input is set, and temperatures of the base and fins are measured. In the corresponding numerical study, the sinks and their environment are modeled using the Fluent 6 software. The results show that heat transfer enhancement due to the fins is not monotonic. The differences between sparsely and densely populated sinks are analyzed for various fin heights. Also assessed are effects of the blocked edges as compared to the previously studied cases where the sink edges were exposed to the surroundings.

Numerical Investigation on Turbulence Statistics and Heat Transfer of a Circular Jet Impinging on a Roughened Flat Plate

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Abdulrahman Alenezi ◽  
Abdulrahman Almutairi ◽  
Hamad Alhajeri ◽  
Abdulaziz Gamil ◽  
Faisal Alshammari
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Numerical Study ◽  
Roughness Element ◽  
Three Dimensional ◽  
Reynolds Numbers ◽  
Target Plate ◽  
Cross Sectional ◽  
Flow Physics ◽  
Baseline Case

Abstract A detailed heat transfer numerical study of a three-dimensional impinging jet on a roughened isothermal surface is presented and is investigated from flow physics vantage point under the influence of different parameters. The effects of the Reynolds number, roughness location, and roughness dimension on the flow physics and heat transfer parameters are studied. Additionally, the relations between average heat transfer coefficient (AHTC) and flow physics including pressure, wall shear and flow vortices with thermodynamic nonequilibrium are offered. This paper studies the effect of varying both location and dimension of the roughness element which took the shape of square cross-sectional continuous ribs to deliver a favorable trade-off between total pressure loss and heat transfer rate. The roughness element was tested for three different radial locations (R/D) = 1, 1.5, and 2 and at each location its height (i.e., width) (e) was changed from 0.25 to 1 mm in incremental steps of 0.25. The study used a jet angle (α) of 90 deg, jet-to-target distance (H/D = 6), and Re ranges from 10,000 to 50,000, where H is the vertical distance between the target plate and jet exit. The results show that the AHTC can be significantly affected by changing the geometry and dimensions of the roughness element. This variation can be either an augmentation of, or decrease in, the (HTC) when compared with the baseline case. An enhancement of 12.9% in the AHTC was achieved by using optimal location and dimensions of the roughness element at specific Reynolds number. However, a diminution between 10% and 30% in (AHTC) was attained by the use of rib height e = 1 mm at Re = 50k. The variation of both rib location and height showed better contribution in increasing heat transfer for low-range Reynolds numbers.

Study on Heat Transfer and Resistance Characteristics of H-Type Finned Tube

2013 ◽  
Vol 805-806 ◽  
pp. 1817-1822 ◽  
Author(s):  
Zhang Jun Wang ◽  
Zhuo Xiong Zeng ◽  
Yi Hua Xu
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Heat Transfer Performance ◽  
Euler Number ◽  
Numerical Study ◽  
Three Dimensional ◽  
Finned Tube ◽  
Comprehensive Performance ◽  
Better Than

Three-dimensional numerical study is performed for heat transfer and resistance characteristics as well as comprehensive performance of two kinds H-type (single and double) finned tube. It is found that the heat transfer and resistance characteristics as well as comprehensive performance of H-type finned tube are influenced by the Reynolds number of gas. With the growth of Reynolds number, the air-side Nusselt number rises gradually and the heat transfer performance gets better and better, whereas the air-side Euler number drops step by step until close to a fixed value. The comprehensive performances of both single H-type finned tube and double ones are weaken progressively. When Reynolds number value is same, the convective heat transfer, pressure drop, air-side Nusselt number and Euler number of single H-type finned tube are bigger than those of double ones. The single H-type finned tube expression is much better than double ones in comprehensive performance and heat transfer.

Thermodynamic Analysis of Heat and Fluid Flow in a Microchannel With Internal Fins

2009 ◽  
Author(s):  
Ramesh Narayanaswamy ◽  
Tilak T. Chandratilleke ◽  
Andrew J. L. Foong
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Thermodynamic Analysis ◽  
Entropy Generation ◽  
High Performance ◽  
Numerical Study ◽  
Three Dimensional ◽  
Heat Sinks ◽  
Heat Transfer Fluid ◽  
Internal Fins

Efficient cooling techniques are one of the critical design requirements for maintaining reliable operational characteristics of modern, miniaturised high performance electronic components. Microchannel heat sinks form an integral part of most devices used for thermal management in electronic equipment cooling. A microchannel of square cross section, having internal longitudinal fins is considered for analysis. A numerical study is carried out to investigate the fluid flow and heat transfer characteristics. Three-dimensional numerical simulations are performed on the microchannel in the presence of a hydrodynamically developed, thermally developing laminar flow. Further on, a thermodynamic analysis is carried out, for a range of fin heights and thermophysical parameters, in order to obtain the irreversibilities due to heat transfer and fluid flow within the microchannel. An optimum fin height, corresponding to the thermodynamically optimum conditions that minimize the entropy generation rates has been obtained. The effect of the presence of internal fins on the entropy generated due to heat transfer, fluid friction, and the total entropy generation is also provided.

Numerical Simulation of Heat Sink Performance With Interrupted and Staggered Fins

2009 ◽  
Author(s):  
Suabsakul Gururatana ◽  
Xianchang Li
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Reynolds Number ◽  
Heat Transfer Rate ◽  
Heat Sink ◽  
Pressure Loss ◽  
Transfer Rate ◽  
Flow Direction ◽  
Heat Sinks ◽  
High Heat Transfer

Extended surfaces (fins) have been used to enhance heat transfer in many applications. In electronics cooling, fin-based heat sinks are commonly designed so that coolants (gas or liquid) are forced to pass through the narrow straight channel. To improve the overall heat sink performance, this study investigated numerically the details of heat sinks with interrupted and staggered fins cooled by forced convection. Long and narrow flow passages or channels are widely seen in heat sinks. Based on the fundamental theory of heat transfer, however, a new boundary layer can be created periodically with interrupted fins, and the entrance region can produce a very high heat transfer coefficient. The staggered fins can take advantage of the lower temperature flow from the upstream. The tradeoff is the higher pressure loss. A major challenge for heat sink design is to reduce the pressure loss while keeping the heat transfer rate high. The effect of fin shapes on the heat sink performance was also examined. Two different shapes under study are rectangular and elliptic with various gaps between the interrupted fins in the flow direction. In addition, studies were also conducted on the parametric effects of Reynolds number and gap length. It is observed that heat transfer increases with the Reynolds number due to the feature of developing boundary layer. If the same pressure drop is considered, the heat transfer rate of elliptic fins is higher than that of rectangular fins.

scholarly journals Numerical Study of Fluid Flow and Heat Transfer Characteristics in Solid and Perforated Finned Heat Sinks Utilizing a Piezoelectric Fan

2019 ◽  
Vol 25 (7) ◽  
pp. 83-103
Author(s):  
Ayser Shamil Salman ◽  
Mohammed A. Nima
Keyword(s):  
Heat Transfer ◽  
Stokes Equations ◽  
Numerical Study ◽  
Air Flow ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Heat Sinks ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Flow Generator

Numerical study is adapted to combine between piezoelectric fan as a turbulent air flow generator and perforated finned heat sinks. A single piezoelectric fan with different tip amplitudes placed eccentrically at the duct entrance. The problem of solid and perforated finned heat sinks is solved and analyzed numerically by using Ansys 17.2 fluent, and solving three dimensional energy and Navier–Stokes equations that set with RNG based k−ε scalable wall function turbulent model. Finite volume algorithm is used to solve both phases of solid and fluid. Calculations are done for three values of piezoelectric fan amplitudes 25 mm, 30 mm, and 40 mm, respectively. Results of this numerical study are compared with previous both numerical and experimental studies and give a good agreement. Numerical solution is invoked to explain the behavior of air flow and temperature distribution for two types of circular axial and lateral perforations. For each type, all the results are compared with an identical solid finned heat sink. Perforations show a remarkable enhanced in the heat transfer characteristics. The results achieved enhancement in the heat transfer coefficient about 12% in axial perforation and 25% in the lateral perforation at the maximum fan amplitude.  

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