Self-adaptive cooling of chips with unevenly distributed high heat fluxes

2022 ◽  
Vol 202 ◽  
pp. 117913
Author(s):  
Xiu Li ◽  
Yimin Xuan
Keyword(s):  
High Heat ◽  
Heat Fluxes ◽  
Self Adaptive

Experimental and Analytical Investigation of Compact Liquid Cooled Heat Sinks

2004 ◽  
Author(s):  
M. Zugic ◽  
J. R. Culham ◽  
P. Teertstra ◽  
Y. Muzychka ◽  
K. Horne ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Tests ◽  
Reynolds Numbers ◽  
High Heat ◽  
Analytical Investigation ◽  
Boundary Resistance ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Air Cooling ◽  
Design Tools

Compact, liquid cooled heat sinks are used in applications where high heat fluxes and boundary resistance preclude the use of more traditional air cooling techniques. Four different liquid cooled heat sink designs, whose core geometry is formed by overlapped ribbed plates, are examined. The objective of this analysis is to develop models that can be used as design tools for the prediction of overall heat transfer and pressure drop of heat sinks. Models are validated for Reynolds numbers between 300 and 5000 using experimental tests. The agreement between the experiments and the models ranges from 2.35% to 15.3% RMS.

An Integral Heat Sink for Cooling Microelectronic Components

1993 ◽  
Vol 115 (3) ◽  
pp. 284-291 ◽  
Author(s):  
S. H. Bhavnani ◽  
C.-P. Tsai ◽  
R. C. Jaeger ◽  
D. L. Eison
Keyword(s):  
Heat Sink ◽  
Silicon Surface ◽  
Numerical Study ◽  
High Heat ◽  
Heat Fluxes ◽  
Silicon Surfaces ◽  
Source Surface ◽  
Mouth Size ◽  
Severe Constraint ◽  
Boiling Incipience

Liquid immersion cooling is rapidly becoming the mechanism of choice for the newest generation of supercomputers. Miniaturization at both the chip and module level places a severe constraint on the size of the heat sink employed to dissipate the high heat fluxes generated. A study was conducted to develop a surface that could augment boiling heat transfer from silicon surfaces under these constraints. The surface created consists of reversed pyramidal features etched directly on to the silicon surface. Experiments were conducted in a saturated pool of refrigerant-113 at atmospheric pressure. The inexpensive crystallographic etching techniques used to create the enhanced features are described in the paper. The main characteristics of interest in the present study were the incipient boiling superheat and the magnitude of the temperature overshoot at boiling incipience. Results were obtained for test sections with various cavity densities, and compared with data for the smooth untreated surface. It was found that incipient boiling superheat was reduced from a range of 27.0–53.0° C for the untreated silicon surface, to a range of 2.5–15.0° C for the enhanced surfaces. The overshoot also decreased considerably; from about 12.0–18.0° C for two classes of untreated surfaces, to a range of 1.5–5.3° C for the enhanced surfaces. The values of the incipient boiling superheat, and those of the overshoot decreased with a decrease in cavity mouth size. Two ratios of heat source surface area to the area of the enhanced surface were studied. The overshoot values obtained for these surfaces were compared with those observed for some commonly used enhanced surfaces. An elementary numerical study was conducted to estimate the magnitude of heat spreading.

Plasma Sprayed Ultra High Temperature Ceramics for Thermal Protection Systems

2000 ◽  
Author(s):  
T. Valente ◽  
C. Bartuli ◽  
G. Visconti ◽  
M. Tului
Keyword(s):  
Plasma Spraying ◽  
High Performance ◽  
Thermal Protection ◽  
Electrical Discharge Machining ◽  
High Heat ◽  
Heat Fluxes ◽  
Space Vehicles ◽  
Ultra High Temperature Ceramics ◽  
Protection Systems ◽  
Plasma Sprayed

Abstract Reusable space vehicles, which must withstand re-entry into the Earth's atmosphere, require external protection systems (TPS) which are usually in the forms of rigid surface in areas of high or moderate working temperature. High heat fluxes and temperatures related to high performance hypervelocity flights also require the use of TPS materials having good oxidation and thermal shock resistance, dimensional stability, and ablation resistance. Components by these materials are usually fabricated, starting from either billets or plate stocks, by uniaxial hot pressing, and complex parts, such as low radius edges, are then obtained by electrical discharge machining technique. This article investigates an alternative fabrication technology, based on plasma spraying, to produce near net shape components. Results of experimental activities, such as optimization of plasma spraying parameters based on a DOE approach, are reported and discussed.

Detachment-parallel recharge explains high discharge fluxes at the TAG hydrothermal field

2021 ◽  
Author(s):  
Lars Rüpke ◽  
Zhikui Guo ◽  
Sven Petersen ◽  
Christopher German ◽  
Benoit Ildefonse ◽  
...  
Keyword(s):  
High Temperature ◽  
Hanging Wall ◽  
Massive Sulfide ◽  
Hydrothermal Activity ◽  
High Heat ◽  
Heat Fluxes ◽  
Long Distance ◽  
High Discharge ◽  
Circulation Mode ◽  
Spreading Ridges

Abstract Submarine massive sulfide deposits on slow-spreading ridges are larger and longer-lived than deposits at fast-spreading ridges1,2, likely due to more pronounced tectonic faulting creating stable preferential fluid pathways3,4. The TAG hydrothermal mound at 26°N on the Mid-Atlantic Ridge (MAR) is a typical example located on the hanging wall of a detachment fault5-7. It has formed through distinct phases of high-temperature fluid discharge lasting 10s to 100s of years throughout at least the last 50,000 years8 and is one of the largest sulfide accumulations on the MAR. Yet, the mechanisms that control the episodic behavior, keep the fluid pathways intact, and sustain the observed high heat fluxes of up to 1800 MW9 remain poorly understood. Previous concepts involved long-distance channelized high-temperature fluid upflow along the detachment5,10 but that circulation mode is thermodynamically unfavorable11 and incompatible with TAG's high discharge fluxes. Here, based on the joint interpretation of hydrothermal flow observations and 3-D flow modeling, we show that the TAG system can be explained by episodic magmatic intrusions into the footwall of a highly permeable detachment surface. These intrusions drive episodes of hydrothermal activity with sub-vertical discharge and recharge along the detachment. This revised flow regime reconciles problematic aspects of previously inferred circulation patterns and can be used as guidance to one critical combination of parameters that can generate substantive mineral systems.

Heat Transfer Enhancement in Compact Phase Change Microchannel Heat Exchangers for High Flux Laser Diodes

2018 ◽  
Author(s):  
Jensen Hoke ◽  
Todd Bandhauer ◽  
Jack Kotovsky ◽  
Julie Hamilton ◽  
Paul Fontejon
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Phase Change ◽  
Flow Boiling ◽  
Laser Diodes ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Maximum Heat ◽  
Average Maximum

Liquid-vapor phase change heat transfer in microchannels offers a number of significant advantages for thermal management of high heat flux laser diodes, including reduced flow rates and near constant temperature heat rejection. Modern laser diode bars can produce waste heat loads >1 kW cm−2, and prior studies show that microchannel flow boiling heat transfer at these heat fluxes is possible in very compact heat exchanger geometries. This paper describes further performance improvements through area enhancement of microchannels using a pyramid etching scheme that increases heat transfer area by ∼40% over straight walled channels, which works to promote heat spreading and suppress dry-out phenomenon when exposed to high heat fluxes. The device is constructed from a reactive ion etched silicon wafer bonded to borosilicate to allow flow visualization. The silicon layer is etched to contain an inlet and outlet manifold and a plurality of 40μm wide, 200μm deep, 2mm long channels separated by 40μm wide fins. 15μm wide 150μm long restrictions are placed at the inlet of each channel to promote uniform flow rate in each channel as well as flow stability in each channel. In the area enhanced parts either a 3μm or 6μm sawtooth pattern was etched vertically into the walls, which were also scalloped along the flow path with the a 3μm periodicity. The experimental results showed that the 6μm area-enhanced device increased the average maximum heat flux at the heater to 1.26 kW cm2 using R134a, which compares favorably to a maximum of 0.95 kw cm2 dissipated by the plain walled test section. The 3μm area enhanced test sections, which dissipated a maximum of 1.02 kW cm2 showed only a modest increase in performance over the plain walled test sections. Both area enhancement schemes delayed the onset of critical heat flux to higher heat inputs.

Convection Heat Transfer of CO2 at Supercritical Pressures in a Vertical Mini Tube

2009 ◽  
Author(s):  
Pei-Xue Jiang ◽  
Zhi-Hui Li ◽  
Chen-Ru Zhao
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Convection Heat Transfer ◽  
High Heat ◽  
Vertical Tube ◽  
Density Variation ◽  
Heat Fluxes ◽  
Convection Heat ◽  
Downward Flow ◽  
Flow Acceleration

This paper presents the experimental and numerical investigation results of the convection heat transfer of CO2 at supercritical pressures in a 0.0992 mm diameter vertical tube at various inlet Reynolds numbers, heat fluxes and flow directions. The effects of buoyancy and flow acceleration resulted from the dramatic properties variation were investigated. Results showed that the local wall temperature varied non-linearly for both upward and downward flow when the heat flux was high. The difference of the local wall temperature between upward flow and downward flow was very small when other test conditions were held the same, which indicates that for supercritical CO2 flowing in a mini tube as employed in this study, the buoyancy effect on the convection heat transfer was quite insignificant, and the flow acceleration induced by the axial density variation with temperature was the main factor that lead to the abnormal local wall temperature distribution at high heat fluxes. The predicted values using the LB low Reynolds number turbulence model correspond well with the measured data. Velocity profiles and turbulence kinetic energy near the wall varying along the tube generated by the numerical simulations were presented to develop a better understanding.

Heat Transfer and Pressure Drop for Flow Boiling of Water in Narrow Vertical Rectangular Channels

2003 ◽  
Author(s):  
Jianyun Shuai ◽  
Rudi Kulenovic ◽  
Manfred Groll
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Flow Boiling ◽  
Bubbly Flow ◽  
High Heat ◽  
Flow Patterns ◽  
Industrial Applications ◽  
Heat Fluxes ◽  
Experimental Conditions ◽  
Rectangular Channels

Flow boiling in small-sized channels attracted extensive investigations in the past two decades due to special requirements for transfer of high heat fluxes from narrow spaces in various industrial applications. Experiments on various aspects of flow boiling in narrow channels were carried out and theoretical attempts were undertaken. But these investigations showed large differences, e.g. up till now the knowledge on the development of flow patterns in small non-circular flow passages is very limited. This paper deals with investigations on flow boiling of water in two rectangular channels with dimensions (width×depth) 2.0×4.0 mm2 and 0.5×2.0 mm2 (corresponding hydraulic diameters are 2.67 mm and 0.8 mm). The pressure at the test section exit is atmospheric. For steady-state experimental conditions the effects of heat flux, mass flux and inlet subcooling on the boiling heat transfer coefficient and the pressure drop are investigated. Flow patterns and the transition of flow patterns along the channel axis are visualized and documented with a video-camera. Bubbly flow, slug flow and annular flow are distinguished in both channels. Preliminary flow pattern maps are generated.

Use of biporous wicks to remove high heat fluxes

2008 ◽  
Vol 28 (4) ◽  
pp. 278-283 ◽  
Author(s):  
Tadej Semenic ◽  
Ying Yu Lin ◽  
Ivan Catton ◽  
David B. Sarraf
Keyword(s):  
High Heat ◽  
Heat Fluxes
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