Novel Lightweight Metal Foam Heat Exchangers

2001 ◽  
Author(s):  
David P. Haack ◽  
Kenneth R. Butcher ◽  
T. Kim ◽  
T. J. Lu
Keyword(s):  
Heat Exchange ◽  
Pore Size ◽  
Heat Exchangers ◽  
Metal Foam ◽  
Heat Removal ◽  
Random Orientation ◽  
Flow Rates ◽  
Small Pore ◽  
Complex Heat Exchange ◽  
Flow Through

Abstract An overview of open cell metal foam materials with application to advanced heat exchange devices is presented. The metal foam materials considered consist of interconnected cells in a random orientation. Metal foam materials, manufacture and fabrication into complex heat exchange components are described. Experiments with flat foam panels brazed to copper sheets shows increasing heat removal effectiveness with decreasing product pore size at equivalent coolant flow rates. However, the high-pressure drop associated with flow through small pore-size material makes the use of larger pore size material more attractive.

Modelling of Effective Thermal Conductance of Metal Foam Contact Thermal Interfaces

2013 ◽  
Author(s):  
Ninad Trifale ◽  
Kazuaki Yazawa ◽  
Eric Nauman
Keyword(s):  
Pore Size ◽  
Heat Sink ◽  
Metal Foam ◽  
Thermal Conductance ◽  
Electronics Cooling ◽  
Target Surface ◽  
Mechanical Stiffness ◽  
Tetrahedral Geometry ◽  
Flow Through ◽  
Modeling Study

We present a modeling study of the effective thermal conductance of metal foams as a thermal interface focusing on the electronics cooling applications. Metal foam material as a porous media has been considered for several applications because of its significantly large surface area for a given volume. In the electronics cooling, aluminum porous heat sinks have been well studied. It is not only cost effective due to the unique production process, but also attractive for the theoretical modeling study to determine the performance. In the past studies, effective thermal conductivity for heat transfer through solid with the tetrahedral geometry, while the pores, assumed to have vacant volumes, has been modeled. Instead of allowing the refrigerant flow through the connected pores in the porous medium, we considered the vacant space filled with stationary air. The major transport of the heat is considered to flow through the solid bridges, which connect the onside to the other side directly. Thus, the porous density for our application shall be relatively lower than the best value for heat sink applications. It must, however, be in a specific range such that it is mechanically compliant to make proper contact to both, the cooling target surface and the heat sink surface. It is obvious that the smaller pore ratio makes the metal foam stiffer. We model the contact thermal performance with considering the mechanical stiffness as a function of pore ratio as well as an intrinsic thermal conductance across the metal foam. Due to the limited literature of the variation of the pore size, we present the first order analysis assuming a fixed and uniform pore size.

Heat Transfer Performance of Porous Copper Fabricated by Lost Carbonate Sintering Process

2009 ◽  
Vol 1188 ◽  
Author(s):  
Liping Zhang ◽  
David Mullen ◽  
Kevin Lynn ◽  
Yuyuan Zhao
Keyword(s):  
Heat Transfer ◽  
Pore Size ◽  
Water Flow ◽  
Heat Transfer Performance ◽  
Water System ◽  
Heat Removal ◽  
Transfer Performance ◽  
Transfer Coefficients ◽  
Flow Rates ◽  
Porous Copper

AbstractThe heat transfer coefficients of porous copper fabricated by the lost carbonate sintering (LCS) process with porosity range from 57% to 82% and pore size from 150 to 1500 μm have been experimentally determined in this study. The sample was attached to the heat plate and assembled into a forced convection system using water as the coolant. The effectiveness of the heat removal from the heat plate through the porous copper-water system was tested under different water flow rates from 0.3 to 2.0 L/min and an input heat flux of 1.3 MW/m2. Porosity has a large effect on the heat transfer performance and the optimum porosity was found to be around 62%. Pore size has a much less effect on the heat transfer performance compared to porosity. High water flow rates enhanced the heat transfer performance for all the samples.

scholarly journals Brownian Motion and Thermophoretic Effects in Mini Channels with Various Heights

Processes ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1965
Author(s):  
Zainab Al Hajaj ◽  
Mohamad Ziad Saghir
Keyword(s):  
Aspect Ratio ◽  
Heat Removal ◽  
Major Effect ◽  
Working Fluid ◽  
Flow Rates ◽  
Pressure Drops ◽  
Optimum Configuration ◽  
Mini Channels ◽  
Flow Through ◽  
The One

Flow-through mini channels have received tremendous interest from researchers over a long period. However, the study of flow between the channel and on top of the channel has received little to no attention. In the present paper, different parameters have been used to investigate this heat enhancement. The height of 10 mini channels has been varied, allowing the corresponding aspect ratio to vary from 3 to 6, 9, and 12. When the aspect ratio is 12, flow circulates through the mini channel only, and when the aspect ratio is less than 12, flow is distributed between the one circulating inside the channel and moving on top of the channel. Different flow rates are studied corresponding to a Reynolds number varying from 250 to 1250 if water is the working fluid. Brownian and thermophoresis effects are taken into consideration to investigate the nanoparticle sedimentation. Results revealed that the optimum configuration, if one needs to take into consideration the friction factor, is 12. If one ignores the pressure drops, then the optimum configuration is when the aspect ratio is equal to 6. This means that the flow interaction between the one circulating in the channel and above the channel plays a major effect in heat removal.

Cross Analysis of Metal Foam Design Parameters for Achieving Desired Fluid Flow

2011 ◽  
Author(s):  
Timothy Hess ◽  
Beshoy Morkos ◽  
Mark Bowman ◽  
Joshua D. Summers
Keyword(s):  
Pore Size ◽  
Metal Foam ◽  
Air Flow ◽  
Maximum Flow ◽  
Design Parameters ◽  
Constant Density ◽  
Cross Sectional ◽  
Manufacturing Method ◽  
Flow Through ◽  
The Cross

This paper presents an experimental study of air flow through open cell metal foams for use as a thermal energy dissipating system. The goal of this paper is to identify the optimum configuration of metal foam design parameters for maximum flow. Four foam blocks were used in the study, representing a range of design parameters: material (copper or aluminum), pore size (5–10 pores per inch), and relative density (ε = 0.875–0.952). The effects of pore size were isolated by comparing air flow through three aluminum foam blocks with constant density and varied pore size. A series of wind tunnel tests were performed to measure the velocity of air flowing through the foam as a function of the free stream air velocity, ranging from 0 to 17.4 mph (7.5 m/s). Results indicated smaller pore sizes and larger densities decreased the amount of airflow through the foam. However, one foam sample produced results that did not fit this trend. Further investigation found this was likely due to the differences in the cross-sectional geometry of the foam ligaments. The ligament geometry, affected by density and manufacturing method, was not constant and not initially considered as a variable of interest. The cross-section shape of the ligaments was found to vary from a rounded triangular shape to a triangle shape with concave surfaces, increasing the amount of drag in the airflow through the sample.

Computational Study of Air Cooled Data Centers Assisted With Locally Distributed Water to Air Heat Exchangers

2013 ◽  
Author(s):  
Tianyi Gao ◽  
Bahgat Sammakia ◽  
Roger Schmidt
Keyword(s):  
Heat Exchanger ◽  
Thermal Management ◽  
Data Center ◽  
Heat Exchangers ◽  
Computational Study ◽  
Air Flow ◽  
Heat Removal ◽  
Air Cooling ◽  
Flow Rates ◽  
The Impact

The heat dissipated by data center equipment continues to increase due to the growing server power year by year. Thermal management continually becomes a challenging problem both from the standpoint of maintaining the equipment within a proper and reliable operation environment, as well as from a total energy cost perspective. With the total heat load increasing, as well as local high density heat fluxes, more cooling air flow rates may be needed by the racks which cannot be sufficiently provided by CRAC units. This may occur during peak periods of operation and may also occur in isolated aisles in the data center. Under such circumstances, just changing the air flow rates to specific aisles may cause unanticipated hot air recirculation into cold aisles which may happen during the transients that arise as the load and air flow rates are changing; henceforth, it may even occur in steady state. This could reduce the reliability of the data center equipment. A hybrid cooling strategy, which uses water to air heat exchangers located at the rear of specific racks to assist the air cooling, can be very effective in solving this problem by removing heat from the rack before it is exhausted into the room. This study describes the impact of this heat exchanger strategy on the thermal management of a data center. In this analytical study, the heat removal percentage and working efficiency of the heat exchanger are presented under different water flowrates and water inlet temperatures. Different case studies are conducted, showing that this method can significantly assist the data center air cooling under scenarios such as, power increases or CRAC unit failure. Detailed function of the heat exchanger on impacting the rack inlet temperatures are also discussed in this paper.

scholarly journals Analysis of Performance of the Wind-Driven Pulverizing Aerator Based on Average Wind Speeds in the Conditions of Góreckie Lake

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2796
Author(s):  
Andrzej Osuch ◽  
Ewa Osuch ◽  
Stanisław Podsiadłowski ◽  
Piotr Rybacki
Keyword(s):  
Mathematical Model ◽  
Wind Speed ◽  
Water Pump ◽  
Average Wind Speed ◽  
Flow Rates ◽  
Wind Speeds ◽  
Average Wind ◽  
Flow Through ◽  
Analysis Of Performance ◽  
Research Period

In the introduction to this paper, the characteristics of Góreckie lake and the construction and operation of the wind-driven pulverizing aerator are presented. The purpose of this manuscript is to determine the efficiency of the pulverizing aerator unit in the windy conditions of Góreckie Lake. The efficiency of the pulverization aerator depends on the wind conditions at the lake. It was necessary to conduct thorough research to determine the efficiency of water flow through the pulverization segment (water pump). It was necessary to determine the rotational speed of the paddle wheel, which depended on the average wind speed. Throughout the research period, measurements of hourly average wind speed were carried out. It was possible to determine the efficiency of the machine by developing a dedicated mathematical model. The latest method was used in the research, consisting of determining the theoretical volumetric flow rates of water in the pulverizing aerator unit, based on average hourly wind speeds. Pulverization efficiency under the conditions of Góreckie Lake was determined based on 6600 average wind speeds for spring, summer and autumn, 2018. Based on the model, the theoretical efficiency of the machine was calculated, which, under the conditions of Góreckie Lake, amounted to 75,000 m3 per year.

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