scholarly journals Pressure Drop of Microchannel Plate Fin Heat Sinks

Micromachines ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 80 ◽  
Author(s):  
Zhipeng Duan ◽  
Hao Ma ◽  
Boshu He ◽  
Liangbin Su ◽  
Xin Zhang
Keyword(s):  
Fluid Dynamics ◽  
Pressure Drop ◽  
Slip Flow ◽  
Numerical Data ◽  
Velocity Slip ◽  
Fundamental Solutions ◽  
Momentum Equation ◽  
Channel Length ◽  
Microchannel Plate ◽  
Heat Sinks

The entrance region constitutes a considerable fraction of the channel length in miniaturized devices. Laminar slip flow in microchannel plate fin heat sinks under hydrodynamically developing conditions is investigated semi-analytically and numerically in this paper. The semi-analytical model for the pressure drop of microchannel plate fin heat sinks is obtained by solving the momentum equation with the first-order velocity slip boundary conditions at the channel walls. The simple pressure drop model utilizes fundamental solutions from fluid dynamics to predict its constitutive components. The accuracy of the model is examined using computational fluid dynamics (CFD) simulations and the experimental and numerical data available in the literature. The model can be applied to either apparent liquid slip over hydrophobic and superhydrophobic surfaces or gas slip flow in microchannel heat sinks. The developed model has an accuracy of 92 percent for slip flow in microchannel plate fin heat sinks. The developed model may be used to predict the pressure drop of slip flow in microchannel plate fin heat sinks for minimizing the effort and expense of experiments, especially in the design and optimization of microchannel plate fin heat sinks.

Effects of Corrugated Roughness on Developed Laminar Flow in Microtubes

2008 ◽  
Vol 130 (3) ◽  
Author(s):  
Zhipeng Duan ◽  
Y. S. Muzychka
Keyword(s):  
Pressure Drop ◽  
Laminar Flow ◽  
Slip Flow ◽  
Velocity Slip ◽  
Momentum Equation ◽  
Analytical Models ◽  
Microchannel Flow ◽  
Compressibility Effect ◽  
Continuum Flow ◽  
Experimental Pressure

The effects of corrugated surface roughness on developed laminar flow in microtubes are investigated. The momentum equation is solved using a perturbation method with slip at the boundary. Novel analytical models are developed to predict friction factor and pressure drop in corrugated rough microtubes for continuum flow and slip flow. The developed model proposes an explanation on the observed phenomenon that some experimental pressure drop results for microchannel flow have shown a significant increase (15–50%) due to roughness. The developed model for slip flow illustrates the coupled effects between velocity slip and small corrugated roughness. Compressibility effect has also been examined and simple models are proposed to predict the pressure distribution and mass flow rate for slip flow in corrugated rough microtubes.

scholarly journals Evaluation of Active Heat Sinks Design under Forced Convection—Effect of Geometric and Boundary Parameters

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2041
Author(s):  
Eva C. Silva ◽  
Álvaro M. Sampaio ◽  
António J. Pontes
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Additive Manufacturing ◽  
Pressure Drop ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sinks ◽  
Trapezoidal Shape ◽  
Computational Fluid Dynamics Simulations ◽  
Dynamics Simulations

This study shows the performance of heat sinks (HS) with different designs under forced convection, varying geometric and boundary parameters, via computational fluid dynamics simulations. Initially, a complete and detailed analysis of the thermal performance of various conventional HS designs was taken. Afterwards, HS designs were modified following some additive manufacturing approaches. The HS performance was compared by measuring their temperatures and pressure drop after 15 s. Smaller diameters/thicknesses and larger fins/pins spacing provided better results. For fins HS, the use of radial fins, with an inverted trapezoidal shape and with larger holes was advantageous. Regarding pins HS, the best option contemplated circular pins in combination with frontal holes in their structure. Additionally, lattice HS, only possible to be produced by additive manufacturing, was also studied. Lower temperatures were obtained with a hexagon unit cell. Lastly, a comparison between the best HS in each category showed a lower thermal resistance for lattice HS. Despite the increase of at least 38% in pressure drop, a consequence of its frontal area, the temperature was 26% and 56% lower when compared to conventional pins and fins HS, respectively, and 9% and 28% lower when compared to the best pins and best fins of this study.

Pressure Drop of Impingement Air Cooled Plate Fin Heat Sinks

2006 ◽  
Vol 129 (2) ◽  
pp. 190-194 ◽  
Author(s):  
Zhipeng Duan ◽  
Y. S. Muzychka
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Parametric Design ◽  
Reynolds Numbers ◽  
Fundamental Solutions ◽  
Heat Sinks ◽  
Momentum Balance ◽  
Rectangular Channels ◽  
Flow Pressure ◽  
Constitutive Components

The performance of impingement air cooled plate fin heat sinks differs significantly from that of parallel flow plate fin heat sinks. A simple impingement flow pressure drop model based on developing laminar flow in rectangular channels is proposed. The model is developed from simple momentum balance and utilizes fundamental solutions from fluid dynamics to predict its constitutive components. To test the validity of the model, experimental measurements of pressure drop are performed with heat sinks of various impingement inlet widths, fin spacings, fin heights, and airflow velocities. The accuracy of the pressure drop model was found to be within 20% of the experimental data taken on four heat sinks and other experimental data from the published literature at channel Reynolds numbers less than 1200. The simple model is suitable for impingement air cooled plate fin heat sinks parametric design studies.

scholarly journals Fluid Flow and Entropy Generation Analysis of Al2O3–Water Nanofluid in Microchannel Plate Fin Heat Sinks

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 739 ◽  
Author(s):  
Hao Ma ◽  
Zhipeng Duan ◽  
Liangbin Su ◽  
Xiaoru Ning ◽  
Jiao Bai ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Pressure Drop ◽  
Aspect Ratio ◽  
Entropy Generation ◽  
Volume Fraction ◽  
Microchannel Plate ◽  
Heat Sinks ◽  
Entropy Generation Rate ◽  
Nanoparticle Volume Fraction ◽  
Channel Aspect Ratio

The flow in channels of microdevices is usually in the developing regime. Three-dimensional laminar flow characteristics of a nanofluid in microchannel plate fin heat sinks are investigated numerically in this paper. Deionized water and Al2O3–water nanofluid are employed as the cooling fluid in our work. The effects of the Reynolds number (100 < Re < 1000), channel aspect ratio (0 < ε < 1), and nanoparticle volume fraction (0.5% < Φ < 5%) on pressure drop and entropy generation in microchannel plate fin heat sinks are examined in detail. Herein, the general expression of the entropy generation rate considering entrance effects is developed. The results revealed that the frictional entropy generation and pressure drop increase as nanoparticle volume fraction and Reynolds number increase, while decrease as the channel aspect ratio increases. When the nanoparticle volume fraction increases from 0 to 3% at Re = 500, the pressure drop of microchannel plate fin heat sinks with ε = 0.5 increases by 9%. It is demonstrated that the effect of the entrance region is crucial for evaluating the performance of microchannel plate fin heat sinks. The study may shed some light on the design and optimization of microchannel heat sinks.

Heat Transfer and Pressure Drop Characteristics of Finned Metal Foam Heat Sinks Under Uniform Impinging Flow

2015 ◽  
Vol 137 (2) ◽  
Author(s):  
S. S. Feng ◽  
J. J. Kuang ◽  
T. J. Lu ◽  
K. Ichimiya
Keyword(s):  
Pressure Drop ◽  
Thermal Performance ◽  
Metal Foam ◽  
Channel Length ◽  
Heat Sinks ◽  
Channel Parameters ◽  
Conventional Plate ◽  
Fin Thickness ◽  
Nusselt Number Correlation ◽  
Impinging Flow

A numerical investigation was carried out to characterize the thermal performance of finned metal foam heat sinks subject to an impinging air flow. The main objective of the study was to quantify the effects of all relevant configurational parameters (channel length, channel width, fin thickness, and fin height) of the heat sink upon the thermal performance. Open-cell aluminum foam having fixed porosity of 0.9118 and fixed pore density of five pores per inch (PPI) was used in the study. A previously validated model based on the porous medium approach was employed for the numerical simulation. Various simulation cases for different combinations of channel parameters were carried out to obtain the Nusselt number correlation. Based on the inviscid impinging flow, a pressure drop correlation was derived for impinging flow in finned metal foam heat sinks. By using these correlations, the thermal performance of finned metal foam heat sinks was compared with the conventional plate-fin heat sinks. It was demonstrated that the finned metal foam heat sinks outperformed the plate-fin heat sinks on the basis of given weight or given pumping power.

Effects of Axial Corrugated Roughness on Low Reynolds Number Slip Flow and Continuum Flow in Microtubes

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Zhipeng Duan ◽  
Y. S. Muzychka
Keyword(s):  
Pressure Drop ◽  
Slip Flow ◽  
Velocity Slip ◽  
Analytical Models ◽  
Axial Distance ◽  
Microchannel Flow ◽  
Compressibility Effect ◽  
Continuum Flow ◽  
Experimental Pressure ◽  
The Stokes Equation

The effect of axial corrugated surface roughness on fully developed laminar flow in microtubes is investigated. The radius of a microtube varies with the axial distance due to corrugated roughness. The Stokes equation is solved using a perturbation method with slip at the boundary. Analytical models are developed to predict friction factor and pressure drop in corrugated rough microtubes for continuum flow and slip flow. The developed model proposes an explanation on the observed phenomenon that some experimental pressure drop results for microchannel flow have shown a significant increase due to roughness. The developed model for slip flow illustrates the coupled effects between velocity slip and small corrugated roughness. Compressibility effect has also been examined and simple models are proposed to predict the pressure distribution and mass flow rate for slip flow in corrugated rough microtubes.

Slip Flow in Rectangular and Annular Ducts

1965 ◽  
Vol 87 (4) ◽  
pp. 1018-1024 ◽  
Author(s):  
W. A. Ebert ◽  
E. M. Sparrow
Keyword(s):  
Pressure Drop ◽  
Rarefied Gas ◽  
Slip Flow ◽  
Velocity Slip ◽  
Density Level ◽  
Axial Pressure ◽  
Slip Regime ◽  
Rarefied Gas Flows ◽  
Axial Pressure Gradient ◽  
Viscous Shear

An analysis has been performed to determine the velocity and pressure-drop characteristics of moderately rarefied gas flows in rectangular and annular ducts. The density level is such that a velocity slip may occur at the duct walls. In general, it is found that the effect of slip is to flatten the velocity distribution relative to that for a continuum flow; furthermore, the axial pressure gradient is diminished under slip-flow conditions. The conditions characterizing the onset of the slip regime have been determined on the basis of a 2 percent reduction in friction factor relative to the continuum value. For all the geometries studied here, the onset of slip occurred at a Knudsen number of 0.003. The effect of compressibility on the axial pressure drop was also investigated. It was found that compressibility increases the pressure drop primarily through an increase in viscous shear rather than through an increase in momentum flux.

Slip Flow in the Hydrodynamic Entrance Region of Circular and Noncircular Microchannels

2009 ◽  
Vol 132 (1) ◽  
Author(s):  
Zhipeng Duan ◽  
Y. S. Muzychka
Keyword(s):  
Friction Factor ◽  
Slip Flow ◽  
Velocity Slip ◽  
Mean Free Path ◽  
Momentum Equation ◽  
Linearization Method ◽  
Asymptotic Results ◽  
Cross Sectional ◽  
Practical Applications ◽  
Continuum Flow

Microscale fluid dynamics has received intensive interest due to the emergence of micro-electro-mechanical systems (MEMS) technology. When the mean free path of the gas is comparable to the channel’s characteristic dimension, the continuum assumption is no longer valid and a velocity slip may occur at the duct walls. Noncircular cross sections are common channel shapes that can be produced by microfabrication. The noncircular microchannels have extensive practical applications in MEMS. The paper deals with issues of hydrodynamic flow development. Slip flow in the entrance of circular and parallel plate microchannels is first considered by solving a linearized momentum equation. It is found that slip flow is less sensitive to analytical linearized approximations than continuum flow and the linearization method is an accurate approximation for slip flow. Also, it is found that the entrance friction factor Reynolds product is of finite value and dependent on the Kn and tangential momentum accommodation coefficient but independent of the cross-sectional geometry. Slip flow and continuum flow in the hydrodynamic entrance of noncircular microchannels has been examined and a model is proposed to predict the friction factor and Reynolds product f Re for developing slip flow and continuum flow in most noncircular microchannels. It is shown that the complete problem may be easily analyzed by combining the asymptotic results for short and long ducts. Through the selection of a characteristic length scale, the square root of cross-sectional area, the effect of duct shape has been minimized. The proposed model has an approximate accuracy of 10% for most common duct shapes.

Stokes Slip Flow in Channel Bend

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
C. Y. Wang
Keyword(s):  
Exact Solution ◽  
Pressure Drop ◽  
Slip Flow ◽  
Velocity Slip ◽  
Meandering Channel ◽  
Channel Bend ◽  
Slip Factor ◽  
Small Ratio ◽  
Gap Width

Abstract Using intrinsic coordinates, the slip flow in a minute meandering channel is studied by perturbation about the small ratio of curvature to inverse half gap width. The exact solution for an annulus shows this ratio can be as large as 0.5 with less than 1% error. Velocity slip on the walls and the pressure drop depend on the slip factor. Formula for the pressure drop in a channel with a single bend is derived.

Two-Phase Flow and Heat Transfer in Rectangular Micro-Channels

2003 ◽  
Author(s):  
Weilin Qu ◽  
Seok-Mann Yoon ◽  
Issam Mudawar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Pattern ◽  
Two Phase Flow ◽  
Flow Patterns ◽  
Heat Sinks ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Micro Channels

Knowledge of flow pattern and flow pattern transitions is essential to the development of reliable predictive tools for pressure drop and heat transfer in two-phase micro-channel heat sinks. In the present study, experiments were conducted with adiabatic nitrogen-water two-phase flow in a rectangular micro-channel having a 0.406 × 2.032 mm cross-section. Superficial velocities of nitrogen and water ranged from 0.08 to 81.92 m/s and 0.04 to 10.24 m/s, respectively. Flow patterns were first identified using high-speed video imaging, and still photos were then taken for representative patterns. Results reveal that the dominant flow patterns are slug and annular, with bubbly flow occurring only occasionally; stratified and churn flow were never observed. A flow pattern map was constructed and compared with previous maps and predictions of flow pattern transition models. Annual flow is identified as the dominant flow pattern for conditions relevant to two-phase micro-channel heat sinks, and forms the basis for development of a theoretical model for both pressure drop and heat transfer in micro-channels. Features unique to two-phase micro-channel flow, such as laminar liquid and gas flows, smooth liquid-gas interface, and strong entrainment and deposition effects are incorporated into the model. The model shows good agreement with experimental data for water-cooled heat sinks.

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