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.

Effect of Flow Arrangements on Thermohydraulic Performance of a Microchannel Heat Sink

2009 ◽  
Author(s):  
Satbir S. Sehgal ◽  
Krishnan Murugesan ◽  
S. K. Mohapatra
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Experimental Studies ◽  
Heat Sinks ◽  
Heat Transfer Analysis ◽  
Maximum Temperature ◽  
Micro Channel ◽  
Flow Conditions ◽  
Micro Channels ◽  
Microchannel Heat Sinks

The advancements in fabricating and utilizing microchannel heat sinks (MCHS) for cooling of electronic devices during the last decade has not been matched by corresponding advances in our fundamental understanding of the unconventional micro fluidics. Many theoretical and experimental studies have been reported for the heat transfer analysis along the direction of flow within the microchannels, but to the best knowledge of the authors, the effect of the size of the inlet and outlet plenum and direction of the flow to the plenums was not studied exhaustively till date. The liquid is supplied to the microchannels via the inlet and outlet plenums and this can be achieved by many flow arrangements. Due to the small size of the channel dimensions, the entrance and exit conditions will significantly affect the heat transfer characteristics of the flow field in the channel. Instability effects at the entrance and exit regions of the micro-channel also need to be fully understood for efficient design of microchannel heat sinks. This paper presents an experimental study that has been conducted to explore the effect of entrance & exit conditions of the liquid flow within a copper micro-channel heat sink (MCHS). Three test pieces having inlet & outlet plenum dimensions of 8mm × 30mm, 10mm × 30 mm and 12 mm × 30 mm each with constant depth of 2.5 mm have been selected. Three different flow arrangements (U-Type, S-type and P-type) are studied for each test piece resulting in total nine flow arrangements. Each micro-channel heat sink contains an array of micro-channels in parallel having individual width of 330μm and channel depth of 2.5 mm. A comparison is made based on thermohydraulic performance of MCHS for different flow conditions at inlet and outlet plenums maintaining constant heat flux. Deionised water has been used in the experiments for the Reynolds number ranging from approximately 220 to 1100. The results are interpreted based on pressure drops and maximum temperature variations for these nine flow arrangements. Tests has been conducted to look for optimized dimensions and flow conditions at inlet and outlet plenums for the given fixed length of microchannels under same conjugate heat transfer conditions. Evaluations of experimental uncertainties have been meticulously made while selecting the instruments used in the experimental facility.

scholarly journals Numerical Investigation of Conjugate Heat Transfer in Rectangular Micro-Channel Heat Sinks under Laminar Flow Conditions

2018 ◽  
Vol 1 (1) ◽  
pp. 196-205
Author(s):  
Haluk Anıl Köse ◽  
Alperen Yıldızeli ◽  
Gökhan Canbolat ◽  
Sertaç Çadırcı
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Heat Transfer Enhancement ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Micro Channel ◽  
Flow Conditions ◽  
Transfer Enhancement ◽  
Constant Heat ◽  
Laminar Flow Conditions

In this study, numerical calculations are performed to investigate steady, laminar convective heat transfer characteristics in rectangular micro channel heat sinks under constant heat fluxes. The investigations are performed at three different inlet Reynolds numbers (400,600 and 800) and constant heat fluxes (500, 1000 and 2000 kW/m2). The aspect ratios of the rectangular micro-channel are selected 1, 1.5 and 2 in the laminar flow regime, respectively. Heat transfer enhancement is the main objective of the study. Nusselt number variation and the pressure drops are found for the given parameters to find the best heat transfer enhancement. It is found that a micro-channel heat sink with square cross-sectional area can be used as an adequate configuration under laminar flow conditions.

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 Flow and Heat Transfer Calculations in Micro-Channel Heat Exchangers

2001 ◽  
Author(s):  
A. K. Saha ◽  
Sumanta Acharya
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Friction Factor ◽  
Critical Reynolds Number ◽  
Numerical Study ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Plane Channel ◽  
Micro Channel ◽  
Flow And Heat Transfer

Abstract A three-dimensional numerical study has been carried out to analyze the unsteady flow and heat transfer in a micro-channel with an array of periodically mounted square cylinders. The current geometry represents a micro-heat exchanger and has potential applications in the cooling of turbine blades and electronic cooling. The cylinder dimensions are of the order of few microns. The three-dimensional unsteady Navier-Stokes and energy equations are solved using higher order temporal and spatial discretizations. The simulations have been carried out for a range of Reynolds number based on cylinder width (180–600) and a Prandtl number of 6.99. Conjugate heat transfer calculations have been employed to account for the conduction in the solid cylinder and convection in the fluid. The flow is found to become unsteady at a critical Reynolds number that falls between 250 and 400. The flow shows quasi-periodic behavior with multiple frequencies at a Reynolds number of 400. The heat transfer enhancement compared to a plane channel is marginal (1.1–1.4 times) for the steady flow cases whereas it is significant (12–15 times) when the flow is unsteady. The friction factor was found to decrease with Reynolds number in both the steady and unsteady regimes. However, the friction factor increases at the critical Reynolds number where it becomes unsteady in nature.

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 Simulation of Gas Flow and Heat Transfer in Cross-Wavy Primary Surface Channel for Microtubine Recuperators

2005 ◽  
Author(s):  
H. X. Liang ◽  
Q. W. Wang ◽  
L. Q. Luo ◽  
Z. P. Feng
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Gas Turbine ◽  
Numerical Study ◽  
High Reliability ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Flow And Heat Transfer ◽  
High Heat Transfer ◽  
The Cross

Three-dimensional numerical simulation was conducted to investigate the flow field and heat transfer performance of the Cross-Wavy Primary Surface (CWPS) recuperators for microturbines. Using high-effective compact recuperators to achieve high thermal efficiency is one of the key techniques in the development of microturbine in recent years. Recuperators need to have minimum volume and weight, high reliability and durability. Most important of all, they need to have high thermal-effectiveness and low pressure-losses so that the gas turbine system can achieve high thermal performances. These requirements have attracted some research efforts in designing and implementing low-cost and compact recuperators for gas turbine engines recently. One of the promising techniques to achieve this goal is the so-called primary surface channels with small hydraulic dimensions. In this paper, we conducted a three-dimensional numerical study of flow and heat transfer for the Cross-Wavy Primary Surface (CWPS) channels with two different geometries. In the CWPS configurations the secondary flow is created by means of curved and interrupted surfaces, which may disturb the thermal boundary layers and thus improve the thermal performances of the channels. To facilitate comparison, we chose the identical hydraulic diameters for the above four CWPS channels. Since our experiments on real recuperators showed that the Reynolds number ranges from 150 to 500 under the operating conditions, we implemented all the simulations under laminar flow situations. By analyzing the correlations of Nusselt numbers and friction factors vs. Reynolds numbers of the four CWPS channels, we found that the CWPS channels have superior and comprehensive thermal performance with high compactness, i.e., high heat transfer area to volume ratio, indicating excellent commercialized application in the compact recuperators.

A review of flow and heat transfer behaviour of nanofluids in micro channel heat sinks

2018 ◽  
Vol 8 ◽  
pp. 477-493 ◽  
Author(s):  
Sunil Kumar ◽  
Anil Kumar ◽  
Alok Darshan Kothiyal ◽  
Mangal Singh Bisht
Keyword(s):  
Heat Transfer ◽  
Heat Sinks ◽  
Micro Channel ◽  
Flow And Heat Transfer
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