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.

Experimental Investigation of Heat Transfer in Impingement Air Cooled Plate Fin Heat Sinks

2005 ◽  
Vol 128 (4) ◽  
pp. 412-418 ◽  
Author(s):  
Zhipeng Duan ◽  
Y. S. Muzychka
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Thermal Resistance ◽  
Thermal Performance ◽  
Heat Transfer Model ◽  
Heat Sinks ◽  
Transfer Model ◽  
Transfer Coefficients ◽  
Developing Flow ◽  
Rectangular Channels

Impingement cooling of plate fin heat sinks is examined. Experimental measurements of thermal performance were performed with four heat sinks of various impingement inlet widths, fin spacings, fin heights, and airflow velocities. The percent uncertainty in the measured thermal resistance was a maximum of 2.6% in the validation tests. Using a simple thermal resistance model based on developing laminar flow in rectangular channels, the actual mean heat transfer coefficients are obtained in order to develop a simple heat transfer model for the impingement plate fin heat sink system. The experimental results are combined into a dimensionless correlation for channel average Nusselt number Nu∼f(L*,Pr). We use a dimensionless thermal developing flow length, L*=(L∕2)∕(DhRePr), as the independent parameter. Results show that Nu∼1∕L*, similar to developing flow in parallel channels. The heat transfer model covers the practical operating range of most heat sinks, 0.01<L*<0.18. The accuracy of the heat transfer model was found to be within 11% 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 proposed heat transfer model may be used to predict the thermal performance of impingement air cooled plate fin heat sinks for design purposes.

Study of Liquid Injection on Pressure Drop of Refrigerant Mixtures Inside Enhanced Surface Tubing

2005 ◽  
Author(s):  
S. M. Sami ◽  
J. Comeau
Keyword(s):  
Pressure Drop ◽  
Positive Impact ◽  
Reynolds Numbers ◽  
Two Phase ◽  
Flow Rates ◽  
Refrigerant Mixtures ◽  
Liquid Injection ◽  
Mass Flow Rates ◽  
Flow Pressure ◽  
Enhanced Surface

Two phase flow pressure drop characteristics observed under liquid injection during boiling of refrigerant mixtures R-404A, R407C and R507 as well as R-410A are presented in this paper. Experiments showed that liquid injection tends to decrease the pressure drop during boiling which will have positive impact in increasing the boiling heat transfer rate, heat flux and system efficiency. However, condensation data demonstrated that liquid injection increases the pressure drop. In addition, the data also reveals that the refrigerant under investigation exhibit the same behaviour at higher Reynolds numbers or mass flow rates.

Experimental Investigation of Single-Phase Flow Pressure Drop Through Rectangular Microchannels

2003 ◽  
Author(s):  
Xiao Tu ◽  
Pega Hrnjak
Keyword(s):  
Surface Roughness ◽  
Single Phase ◽  
Single Channel ◽  
Reynolds Numbers ◽  
Flow Friction ◽  
Aspect Ratios ◽  
Friction Factors ◽  
Rectangular Channels ◽  
Channel Surface ◽  
Flow Pressure

The current work focused on determining the friction factors in five rectangular channels with hydraulic diameters varying from 69.5 to 304.7 μm and with aspect ratios changing from 0.09 to 0.24. The single-channel test sections were carefully designed such that the friction factors could be determined accurately from the experimental data. R134a liquid and vapor were used as the testing fluids. During the experiments, the Reynolds numbers were varied between 112 and 9180. The measured friction factors were compared with the conventional correlations. The results support such a general agreement in the literature that the flow friction in microchannels may be different from the conventional results. However, a more important finding is that when the channel surface roughness was low, even for the smallest channel tested, both the laminar friction factor and the critical Reynolds number approach the conventional values. In the turbulent region, the surface roughness has great effect on the flow friction even for the smoothest channel tested (Ra/Dh = 0.14%).

Study of Pressure Drop of Refrigerant Mixtures Inside Enhanced Surface Tubing

2001 ◽  
Author(s):  
S. M. Sami ◽  
J. Grell
Keyword(s):  
Pressure Drop ◽  
Reynolds Numbers ◽  
The Other ◽  
Phase Flow ◽  
Specific Pressure ◽  
Two Phase ◽  
Transfer Rates ◽  
Refrigerant Mixtures ◽  
Flow Pressure ◽  
Enhanced Surface

Abstract Two phase flow pressure drop characteristics observed during condensation and boiling of azeotropic refrigerant mixtures R-404A (R125/R134a/R143a:44/4/52), R-407B (R32/R125/ R134a:10/70/20), R407C (R32/R125/R134a:23/25/52) and R408A (R22/R125/R143a:46/7/47) are presented in this paper. Experiments showed that for liquid Reynolds numbers higher than 3.00 E06, R-408A appears to have greater heat transfer rates than the other blends under investigation. Furthermore, it is quite evident from this data that R-407C has the highest specific pressure drop among the refrigerants under investigation.

Thermal Analysis and Experimental Validation of Laminar Heat Transfer and Pressure Drop in Serpentine Channel Heat Sinks for Electronic Cooling

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Xiaohong Hao ◽  
Bei Peng ◽  
Gongnan Xie ◽  
Yi Chen
Keyword(s):  
Pressure Drop ◽  
Thermal Resistance ◽  
Reynolds Numbers ◽  
Electronic Cooling ◽  
Heat Sinks ◽  
Total Thermal Resistance ◽  
Serpentine Channel ◽  
Resistance Network ◽  
Aspect Ratios ◽  
Resistance Network Model

In this paper, a thermal resistance network analytical model is proposed to investigate the thermal resistance and pressure drop in serpentine channel heat sinks with 180 deg bends. The total thermal resistance is obtained using a thermal resistance network model based on the equivalent thermal circuit method. Pressure drop is derived considering straight channel and bend loss because the bends interrupt the hydrodynamic boundary periodically. Considering the effects of laminar flow development and redevelopment, the bend loss coefficient is obtained as a function of the Reynolds number, aspect ratios, widths of fins, and turn clearances, through a three-regime correlation. The model is then experimentally validated by measuring the temperature and pressure characteristics of heat sinks with different Reynolds numbers and different geometric parameters. Finally, the temperature-rise and pressure distribution of the thermal fluid with Reynolds numbers of 500, 1000, and 1500 are examined utilizing this model.

Pressure Drop of Horizontal Air–Water Slug Flow in Different Configurations of Corrugated Pipes

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Ana Luiza B. Santana ◽  
Moisés A. Marcelino Neto ◽  
Rigoberto E. M. Morales
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Industrial Application ◽  
Slug Flow ◽  
Phase Flow ◽  
Dynamic Changes ◽  
Two Phase ◽  
Pressure Drops ◽  
Flow Pressure ◽  
Increased Pressure

Abstract Corrugated pipes (CP) have regularly shaped and spaced cavities on their internal walls that can induce dynamic changes in the flow, such as increased pressure drops. Offshore petroleum production pipelines are an example of an industrial application of CPs, known as flexible lines. Slug flow is the most challenging flow pattern in those lines due to its complex hydrodynamics. A number of previous studies proposed correlations to predict the two-phase flow pressure drops in smooth pipes (SPs). However, limited researches have evaluated the pressure drops associated with liquid–gas slug flow in CPs. In this work, experiments to analyze the pressure drops in horizontal air–water slug flow under different configurations of CPs were carried out. The tests were performed in three different CP internal diameters (IDs) (26, 40, and 50 mm) with different cavity widths (1.2, 1.6, and 2.0 mm). The effects of the internal diameters and the cavity widths on the pressure drops associated with slug flow were analyzed. Results demonstrated that the pressure drops increase with increasing cavity widths. The experimental data were fitted and a pressure drop correlation using the concept of multiplier factor was proposed. Comparisons between predictions and the experimental data proved to be within ±10% accuracy.

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.

Condensation of Refrigerant in a Multi-Port Channel

2003 ◽  
Author(s):  
Shigeru Koyama ◽  
Ken Kuwahara ◽  
Koichi Nakashita
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Surface Tension ◽  
Pressure Drop ◽  
Large Diameter ◽  
Hydraulic Diameter ◽  
Enhancement Effect ◽  
Frictional Pressure Drop ◽  
New Correlation ◽  
Rectangular Channels

In the present paper, the local characteristics of pressure drop and heat transfer are investigated experimentally for the condensation of pure refrigerant R134a in four kinds of multi-port extruded aluminum tubes of about 1 mm in hydraulic diameter. Two tubes are composed of plane rectangular channels, while remaining two tubes are composed of rectangular channels with straight micro-fins. The experimental data of frictional pressure drop (FPD) and heat transfer coefficient (HTC) in plane tubes are compared with previous correlations, most of which are proposed for the condensation of pure refrigerant in a relatively large diameter tube. It is confirmed that parameters such as tube diameter, surface tension, free convection in FPD and HTC correlations should be taken into account more precisely. Considering the effects of surface tension and kinematic viscosity, new correlation of FPD is developed based on the Mishima-Hibiki correlation. New correlation of HTC is also developed modifying the effect of diameter in the correlation of Haraguchi et al. Both new correlations are compared with experimental data for tubes with micro-fins. Satisfactory agreement between experimental and predicted results is obtained. This means that the micro-fin effect is taken into account by using hydraulic diameter and the heat transfer enhancement effect of micro-fins is mainly due to the enlargement of heat transfer area.

Fluid Flow Characteristics for Partially-Confined Compact Plain-Plate-Fin Heat Sinks

2005 ◽  
Author(s):  
M. P. Wang ◽  
T. Y. Wu ◽  
J. T. Horng ◽  
C. Y. Lee ◽  
Y. H. Hung
Keyword(s):  
Experimental Data ◽  
Fluid Flow ◽  
Pressure Drop ◽  
Heat Sink ◽  
Flow Behavior ◽  
Flow Characteristics ◽  
Heat Sinks ◽  
Experimental Investigations ◽  
Channel Height ◽  
Fluid Flow Characteristics

A series of experimental investigations with a stringent measurement method on the study of the fluid flow behavior for confined compact heat sinks in forced convection have been successfully conducted. In the present study, a theoretical model to effectively predict the velocity and pressure drop for partially-confined heat sinks has been successfully developed. The air velocities flowing into heat sink Us through side bypass U1 and top bypass U2 for various 0.47&lt;H/Hc&lt;1 ratios are evaluated, where H/Hc is the ratio of the heat sink height to channel height. The maximum and average deviations of the velocities predicted by the present model from the experimental data are less than 20.31% and 13.13%, respectively, for confined compact heat sinks. Besides, the results show a good agreement between the predicted results and the experimental data of the pressure drop for the cases of H/Hc = 1. Nevertheless, the relative deviation of the predictions from the experimental data becomes more significant with decreasing H/Hc ratio, i.e., increasing the top bypass of confined compact heat sink. A new modified correlation of pressure drop including the H/Hc effect is presented. The maximum and average deviations of the results predicted by the new correlation from the experimental data are 14.48% and 7.72%, respectively.

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