Heat Switch to Control the Local Thermal Resistance Using Liquid Pillar Control

2009 ◽  
Author(s):  
Su-Heon Jeong ◽  
Wataru Nakayama ◽  
Sun-Kyu Lee
Keyword(s):  
Thermal Resistance ◽  
Thermal Management ◽  
Room Temperature ◽  
Hydrophobic Surface ◽  
Specific Area ◽  
Flow Regulation ◽  
Channel State ◽  
Stop Valve ◽  
Switch Operation ◽  
Electronics Packages

This paper presents the heat switch for electronic package to be operated at room temperature. The heat switch controls the thermal resistance between two objective plates using liquid pillar. By forming the liquid pillar, the temperature of the specific area can be controlled locally. In order to realize the desired switch operation, the heat switch should be provided with reservoir, switching channel and breathing channel. The channels are carefully designed to control the liquid pillar precisely. The liquid pillar formation depends on the liquid contact angle. The designed channel geometry can generate hydrophobic surface by using suddenly diverging shape like as capillary stop valve. Thus, the liquid pillar can be created at desired point with high stability. To verify the switch operation, the switch panel was designed and experiments were performed on a designed switch for the liquid pillar control and the heat flow regulation. The experiments show that the heat switch is able to work properly. Also, the temperature distribution and thermal resistance was changed in accordance with channel state as desired. As a result, the heat switch can be a good candidate of thermal management in the commercial electronics packages.

The Liquid Bridge Heat Switch Design With Considering the Pressure Behavior to Regulate the Thermal Resistance for the Temperature Control

2010 ◽  
Author(s):  
Su-Heon Jeong ◽  
Wataru Nakayama ◽  
Sun-Kyu Lee
Keyword(s):  
Thermal Resistance ◽  
Liquid Bridge ◽  
Room Temperature ◽  
Size Control ◽  
Geometry Design ◽  
Switch Operation ◽  
Micro Channels ◽  
Promising Solution ◽  
Switch Design

Various types of heat switch have been suggested as the promising solution of thermal management in the extremely low temperature condition. Recently, the heat switch based on the liquid for the room temperature condition has been investigated to control the thermal resistance of the electronic devices. The presented heat switch was composed of several micro channels. The key technology of the heat switch operation for room temperature is the fluid control. The existing studied indicates that the flow regulation was achieved by simple channel geometry design based on the burst pressure theory. In this research, the design of the liquid bridge heat switch was presented and the pressure characterization of the designed switch was carried out. The supplying liquid generates the liquid bridge between two plates. The thermal resistance between two plates depends on the liquid bridge diameter and height. The liquid bridge size control is achieved based on the pressure characterization.

Kinetics of the Thermal Disappearance of Radicals Formed During the Radiolysis of Aspartic Acid

2009 ◽  
Vol 59 (12) ◽  
Author(s):  
Mihai Contineanu ◽  
iulia Contineanu ◽  
Ana Neacsu ◽  
Stefan Perisanu
Keyword(s):  
Thermal Resistance ◽  
Aspartic Acid ◽  
Room Temperature ◽  
Esr Spectra ◽  
Complex Mechanism ◽  
Radical Species ◽  
Mechanisms Of Formation ◽  
Kinetics Of

The radiolysis of the isomers L-, D- and DL- of the aspartic acid, in solid polycrystalline state, was investigated at room temperature. The analysis of their ESR spectra indicated the formation of at least two radicalic entities. The radical, identified as R3, resulting from the deamination of the acid, exhibits the highest concentration and thermal resistance. Possible mechanisms of formation of three radical species are suggested, based also on literature data. The kinetics of the disappearance of radical R3 indicated a complex mechanism. Three possible variants were suggested for this mechanism.

Asymmetric Sandwich Structural Cellulose-based Film with Self-supported MXene and AgNW Layers for Flexible Electromagnetic Interference Shielding and Thermal Management

Nanoscale ◽  
2021 ◽  
Author(s):  
Bing Zhou ◽  
Qingtao Li ◽  
Penghui Xu ◽  
Yuezhan Feng ◽  
Jianmin Ma ◽  
...  
Keyword(s):  
Thermal Resistance ◽  
Thermal Management ◽  
Electromagnetic Interference ◽  
High Potential ◽  
Emi Shielding ◽  
Electromagnetic Interference Shielding ◽  
Conductive Films

Flexible cellulose-based conductive films reveal the high potential in electromagnetic interference (EMI) shielding and thermal management applications. However, the high contact electrical/thermal resistance in these films is still one of...

Thermal Resistance of Fly Ash Geopolymers with Alumina as Additive

2018 ◽  
Vol 281 ◽  
pp. 182-188
Author(s):  
Yong Sing Ng ◽  
Yun Ming Liew ◽  
Cheng Yong Heah ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamarudin Hussin
Keyword(s):  
Elevated Temperature ◽  
Fly Ash ◽  
Thermal Resistance ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Room Temperature ◽  
Strength Degradation ◽  
Alumina Addition ◽  
Higher Temperature ◽  
Temperature Exposure

The present work investigates the effect of alumina addition on the thermal resistance of fly ash geopolymers. Fly ash geopolymers were synthesised by mixing fly ash with activator solution (A mixture of 12M sodium hydroxide and sodium silicate) at fly ash/activator ratio of 2.5 and sodium silicate/sodium hydroxide ratio of 2.5. The alumina (0, 2 and 4 wt %) was added as an additive. The geopolymers were cured at room temperature for 24 hours and 60°C for another 24 hours. After 28 days, the geopolymers was heated to elevated temperature (200 - 1000°C). For unexposed geopolymers, the addition of 2 wt % of alumina increased the compressive strength of fly ash geopolymers while the strength decreased when the content increased to 4 wt.%. The temperature-exposed geopolymers showed enhancement of strength at 200°C regardless of the alumina content. The strength reduced at higher temperature exposure (> 200°C). Despite the strength degradation at elevated temperature, the strength attained was relatively high in the range of 13 - 45 MPa up to 1000°C which adequately for application as structural materials.

Vapor grown carbon fiber reinforced aluminum composites with very high thermal conductivity

1995 ◽  
Vol 10 (2) ◽  
pp. 247-250 ◽  
Author(s):  
Jyh-Ming Ting ◽  
Max L. Lake
Keyword(s):  
Thermal Conductivity ◽  
Carbon Fiber ◽  
Thermal Management ◽  
Room Temperature ◽  
Electronic Devices ◽  
High Thermal Conductivity ◽  
Aluminum Metal ◽  
Aluminum Metal Matrix Composite ◽  
New Material ◽  
Very High

The first use of continuous vapor grown carbon fiber (VGCF) as reinforcement in aluminum metal matrix composite (Al MMC) is reported. Al MMC represents a new material for thermal management in high-power, high-density electronic devices. Due to the ultrahigh thermal conductivity of VGCF, 1950 W/m-K at room temperature, VGCF-reinforced Al MMC exhibits excellent thermal conductivity that cannot be achieved by using any other carbon fiber as reinforcement. An unprecedented high thermal conductivity of 642 W/m-K for Al MMC was obtained by using 36.5% of VGCF.

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