scholarly journals Heat Technology Aiming to Mitigate Structural Heat Sinks for Drywood Termite (Blattodea: Kalotermitidae) Management

2021 ◽  
Author(s):  
Jia-Wei Tay ◽  
Devon James
Keyword(s):  
Heat Treatment ◽  
Heat Sink ◽  
High Heat ◽  
Heat Sinks ◽  
Treatment Protocols ◽  
Ambient Temperatures ◽  
Heat Technology ◽  
Wooden Cube ◽  
Drywood Termites

With heat treatments to control drywood termites (Blattodea: Kalotermitidae), the presence of heat sinks, which have insulating properties, causes heat to be distributed unevenly throughout the treatment areas. Drywood termites may move to galleries in heat sink areas to avoid exposure to lethal temperatures. To mitigate heat sink effect, studies were conducted in Crytotermes brevis-infested homes in Honolulu, Hawaii to reflect real-world scenarios; either a standard heat treatment performed by a heat remediation company or improved heat treatment methods were used. For improved treatments, heated air was directed into the toe-kick voids of cabinets to reduce heat sink effects. Eight thermistor sensors were placed inside toe-kick voids, in the treatment zone, embedded inside cabinets or the sidewall, or in a wooden cube to monitor internal and ambient temperatures to ensure sufficiently high heat reached all areas. Target temperatures above 46 °C or 50 °C were recorded in all areas for 120 minutes. A pretreatment inspection was conducted, and follow-up inspections were performed at 6 months posttreatment to confirm termite inactivity using visual observations and a Termatrac device. In improved treatment homes, no termite activity was found after treatment. Efficacious heat treatment protocols for structures using the improved method are proposed.

scholarly journals Field Demonstration of Heat Technology to Mitigate Heat Sinks for Drywood Termite (Blattodea: Kalotermitidae) Management

2021 ◽  
Author(s):  
Jia-Wei Tay ◽  
Devon James
Keyword(s):  
Heat Treatment ◽  
Heat Sink ◽  
Heat Sinks ◽  
Treatment Protocols ◽  
Heat Technology ◽  
Heat Penetration ◽  
Wooden Cube ◽  
Improved Methods ◽  
Drywood Termites

With heat treatments to control drywood termites (Blattodea: Kalotermitidae), the presence of heat sinks causes heat to be distributed unevenly throughout the treatment areas. Drywood termites may move to galleries in heat sink areas to avoid exposure to lethal temperatures. Our studies were conducted in Crytotermes brevis-infested condominiums in Honolulu, Hawaii to reflect real-world condominium scenarios; either a standard heat treatment performed by a heat remediation company or an improved heat treatment was used. For improved treatments, heated air was directed into the toe-kick voids of C. brevis infested cabinets to reduce heat sink effects and increase the heat penetration into these difficult-to-heat areas. Eight thermistor sensors placed inside toe-kick voids, treatment zone, embedded inside cabinets’ sidewalls, and in a wooden cube recorded target temperatures of above 46 °C or 50 °C for 120 minutes. A pretreatment and follow-up inspections were performed at 6 months posttreatment to monitor termite inactivity using visual observations and by recording the numbers of spiked peaks on a microwave technology termite detection device (Termatrac). In improved treatment condominiums, significantly higher numbers of spiked peaks were recorded at pretreatment as compared to 6 months posttreatment. Efficacious heat treatment protocols using the improved methods are proposed.

scholarly journals Field Demonstration of Heat Technology to Mitigate Heat Sinks for Drywood Termite (Blattodea: Kalotermitidae) Management

Insects ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1090
Author(s):  
Jia-Wei Tay ◽  
Devon James
Keyword(s):  
Heat Treatment ◽  
Heat Sink ◽  
Heat Sinks ◽  
Treatment Protocols ◽  
Heat Technology ◽  
Heat Penetration ◽  
Pre Treatment ◽  
Wooden Cube ◽  
Drywood Termites

With heat treatments to control drywood termites (Blattodea: Kalotermitidae), the presence of heat sinks causes heat to be distributed unevenly throughout the treatment areas. Drywood termites may move to galleries in heat sink areas to avoid exposure to lethal temperatures. Our studies were conducted in Crytotermes brevis-infested condominiums in Honolulu, Hawaii to reflect real-world condominium scenarios; either a standard heat treatment performed by a heat remediation company, or an improved heat treatment was used. For improved treatments, heated air was directed into the toe-kick voids of C. brevis infested cabinets to reduce heat sink effects and increase heat penetration into these difficult-to-heat areas. Eight thermistor sensors placed inside the toe-kick voids, treatment zone, embedded inside cabinets’ sidewalls, and in a wooden cube recorded target temperatures of above 46 °C or 50 °C for 120 min. Pre-treatment and follow-up inspections were performed at 6 months posttreatment to monitor termite inactivity using visual observations and by recording the numbers of spiked peaks on a microwave technology termite detection device (Termatrac). In improved treatment condominiums, significantly higher numbers of spiked peaks were recorded at pre-treatment as compared to 6 months posttreatment. Efficacious heat treatment protocols using the improved methods are proposed.

scholarly journals Optimal design of subcooled triangular microchannel heat sink exchangers with variable heat loads for high performance cooling

2021 ◽  
Vol 2116 (1) ◽  
pp. 012052
Author(s):  
David Olugbenga Ariyo ◽  
Tunde Bello-Ochende
Keyword(s):  
Heat Sink ◽  
High Performance ◽  
Flow Boiling ◽  
High Heat ◽  
Geometric Optimization ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Microchannel Heat Sinks

Abstract Deionized water at a temperature of 25 °C was used as the cooling fluid and aluminium as the heat sink material in the geometric optimization and parameter modelling of subcooled flow boiling in horizontal equilateral triangular microchannel heat sinks. The thermal resistances of the microchannels were minimized subject to fixed volume constraints of the heat sinks and microchannels. A computational fluid dynamics (CFD) ANSYS code used for both the simulations and the optimizations was validated by the available experimental data in the literature and the agreement was good. Fixed heat fluxes between 100 and 500 W/cm2 and velocities between 0.1 and 7.0 m/s were used in the study. Despite the relatively high heat fluxes in this study, the base temperatures of the optimal microchannel heat sinks were within the acceptable operating range for modern electronics. The pumping power requirements for the optimal microchannels are low, indicating that they can be used in the cooling of electronic devices.

Development of Heat Sinks for Air Cooling and Water Cooling Using Lotus-Type Porous Metals

2011 ◽  
Author(s):  
H. Chiba ◽  
T. Ogushi ◽  
H. Nakajima
Keyword(s):  
Heat Transfer ◽  
Porous Materials ◽  
Heat Sink ◽  
High Heat ◽  
Heat Sinks ◽  
Air Cooling ◽  
Water Cooling ◽  
Cooling Performance ◽  
High Heat Transfer ◽  
Micro Channels

In recent years, since heat dissipation rates and high frequency electronic devices have been increasing, a heat sink with high heat transfer performance is required to cool these devices. Heat sink utilizing micro-channels with several ten microns are expected to provide an excellent cooling performance because of their high heat transfer capacities due to small channel. Therefore, various porous materials such as cellular metals have been investigated for heat sink applications. However, heat sink using conventional porous materials has a high pressure drop because the cooling fluid flow through the pores is complex. Among the described porous materials, a lotus-type porous metal with straight pores is preferable for heat sinks due to the small pressured drop. In present work, cooling performance of the lotus copper heat sink for air cooling and water cooling is introduced. The experimental data for air cooling show 13.2 times higher than that for the conventional groove fins. And, the data for the water cooling show 1.7 times higher than that for the micro-channels. It is concluded that lotus copper heat sink is the most prospective candidate for high power electronics devices.

Experimental and Computational Characterization of a Heat Sink Tester

2007 ◽  
Author(s):  
Aalok Trivedi ◽  
Nikhil Lakhkar ◽  
Madhusudhan Iyengar ◽  
Michael Ellsworth ◽  
Roger Schmidt ◽  
...  
Keyword(s):  
Heat Sink ◽  
Accurate Determination ◽  
Thermal Characterization ◽  
High Heat ◽  
Heat Fluxes ◽  
Thermal Design ◽  
Heat Sinks ◽  
Junction Temperature ◽  
Air Cooling

With the continuing industry trends towards smaller, faster and higher power devices, thermal management continues to be extremely important in the development of electronics. In this era of high heat fluxes, air cooling still remains the primary cooling solution in desktops mainly due to its cost. The primary goal of a good thermal design is to ensure that the chip can function at its rated frequency or speed while maintaining the junction temperature within the specified limit. The first and foremost step in measurement of thermal resistance and hence thermal characterization is accurate determination of junction temperature. Use of heat sinks as a thermal solution is well documented in the literature. Previously, the liquid cooled cold plate tester was studied using a different approach and it was concluded that the uncertainty in heat transfer coefficient was within 8% with errors in appropriate parameters, this result was supported by detailed uncertainty analysis based on Monte-Carlo simulations. However, in that study the tester was tested computationally. In this paper, testing and characterization of a heat sink tester is presented. Heat sinks were tested according to JEDEC JESD 16.1 standard for forced convection. It was observed that the error between computational and experimental values of thermal resistances was 10% for the cases considered.

scholarly journals Thermal Performance Investigation of Slotted Fin Minichannel Heat Sink for Microprocessor Cooling

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6347
Author(s):  
Taha Baig ◽  
Zabdur Rehman ◽  
Hussain Ahmed Tariq ◽  
Shehryar Manzoor ◽  
Majid Ali ◽  
...  
Keyword(s):  
Heat Flux ◽  
Thermal Management ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
Heat Removal ◽  
High Heat ◽  
Heat Sinks ◽  
High Heat Flux ◽  
Base Temperature ◽  
High Processing

Due to high heat flux generation inside microprocessors, water-cooled heat sinks have gained special attention. For the durability of the microprocessor, this generated flux should be effectively removed. The effective thermal management of high-processing devices is now becoming popular due to high heat flux generation. Heat removal plays a significant role in the longer operation and better performance of heat sinks. In this work, to tackle the heat generation issues, a slotted fin minichannel heat sink (SFMCHS) was investigated by modifying a conventional straight integral fin minichannel heat sink (SIFMCHS). SFMCHSs with fin spacings of 0.5 mm, 1 mm, and 1.5 mm were numerically studied. The numerical results were then compared with SIFMCHSs present in the literature. The base temperatures recorded for two slots per fin minichannel heat sink (SPFMCHS), with 0.5 mm, 1 mm, and 1.5 mm fin spacings, were 42.81 °C, 46.36 °C, and 48.86 °C, respectively, at 1 LPM. The reductions in base temperature achieved with two SPFMCHSs were 9.20 %, 8.74 %, and 7.39% for 0.5 mm, 1 mm, and 1.5 mm fin spacings, respectively, as compared to SIFMCHSs reported in the literature. The reductions in base temperature noted for three SPFMCHSs were 8.53%, 9.05%, and 5.95% for 0.5 mm, 1 mm, and 1.5 mm fin spacings, respectively, at 1 LPM, as compared to SIFMCHSs reported in the literature. In terms of heat transfer performance, the base temperature and thermal resistance of the 0.5 mm-spaced SPFMCHS is better compared to 1 mm and 1.5 mm fin spacings. The uniform temperature distribution at the base of the heat sink was observed in all cases solved in current work.

Vapor Chambers in Blade Server CPU Cooling Solutions

2007 ◽  
Author(s):  
Matt Connors
Keyword(s):  
Heat Sink ◽  
High Heat ◽  
Heat Sinks ◽  
High Heat Flux ◽  
Air Cooling ◽  
Vapor Chamber ◽  
Two Phase ◽  
Blade System ◽  
Overall Resistance ◽  
Aluminum Base

Current blade processors need air cooling solutions that dissipate 100–300 watts with heat sinks that are less than 30 mm high. In order to cool these processors, the heat sink base has to grow in length and width to compensate for the lack of available height. As these dimensions grow, decreasing the base spreading of the heat sink becomes an important factor is decreasing the overall resistance of the heat sink. A vapor chamber used as a substitute to common copper or aluminum as the base of the heat sink can increase performance by 20–25%. A vapor chamber is a two phase heat transport system that significantly reduces the spreading resistance in applications where there is a high heat flux processor coupled with a large heat sink. In this paper, a CFD model will be constructed to predict the performance gains realized by using a vapor chamber base in lieu of a copper or aluminum base. These predictions will then be experimentally tested to confirm the modeling parameters and the actual measured thermal performance of the heat sink. By utilizing vapor chambers in heat sink design, thermal engineers will gain valuable heat sink performance within the constraints imposed by the blade system architecture.

scholarly journals Effect of Surface Microstructure on the Heat Dissipation Performance of Heat Sinks Used in Electronic Devices

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 265
Author(s):  
Yuxin You ◽  
Beibei Zhang ◽  
Sulian Tao ◽  
Zihui Liang ◽  
Biao Tang ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Thermal Radiation ◽  
Heat Sink ◽  
Heat Dissipation ◽  
Electronic Devices ◽  
High Heat ◽  
Heat Sinks ◽  
High Heat Flux ◽  
Thermal Emissivity ◽  
Effect Of Surface

Heat sinks are widely used in electronic devices with high heat flux. The design and build of microstructures on heat sinks has shown effectiveness in improving heat dissipation efficiency. In this paper, four kinds of treatment methods were used to make different microstructures on heat sink surfaces, and thermal radiation coating also applied onto the heat sink surfaces to improve thermal radiation. The surface roughness, thermal emissivity and heat dissipation performance with and without thermal radiation coating of the heat sinks were studied. The result shows that with an increase of surface roughness, the thermal emissivity can increase up to 2.5 times. With thermal radiation coating on a surface with microstructures, the heat dissipation was further improved because the heat conduction at the coating and heat sink interface was enhanced. Therefore, surface treatment can improve the heat dissipation performance of the heat sink significantly by enhancing the thermal convection, radiation and conduction.

Optimized Thermoelectric Module-Heat Sink Assemblies for Precision Temperature Control

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
Rui Zhang ◽  
Marc Hodes ◽  
David A. Brooks ◽  
Vincent P. Manno
Keyword(s):  
Thermal Resistance ◽  
Ambient Temperature ◽  
Thermoelectric Material ◽  
Temperature Control ◽  
Heat Sink ◽  
Heat Sinks ◽  
Ambient Temperatures ◽  
Precision Temperature ◽  
Precision Temperature Control ◽  
Heat Loads

Robust precision temperature control of heat-dissipating photonics components is achieved by mounting them on thermoelectric modules (TEMs), which are in turn mounted on heat sinks. However, the power consumption of such TEMs is high. Indeed, it may exceed that of the component. This problem is exacerbated when the ambient temperature and/or component heat load vary as is normally the case. In the usual packaging configuration, a TEM is mounted on an air-cooled heat sink of specified thermal resistance. However, heat sinks of negligible thermal resistance minimize TEM power for sufficiently high ambient temperatures and/or heat loads. Conversely, a relatively high thermal resistance heat sink minimizes TEM power for sufficiently low ambient temperatures and heat loads. In the problem considered, total footprint of thermoelectric material in a TEM, thermoelectric material properties, component operating temperature, relevant component-side thermal resistances, and ambient temperature range are prescribed. Moreover, the minimum and maximum rates of heat dissipation by the component are zero and a prescribed value, respectively. Provided is an algorithm to compute the combination of the height of the pellets in a TEM and the thermal resistance of the heat sink attached to it, which minimizes the maximum sum of the component and TEM powers for permissible operating conditions. It is further shown that the maximum value of this sum asymptotically decreases as the total footprint of thermoelectric material in a TEM increases. Implementation of the algorithm maximizes the fraction of the power budget in an optoelectronics circuit pack available for other uses. Use of the algorithm is demonstrated through an example for a typical set of conditions.

Proposal of a Micro/Mini Cooling Device Using Fins-Installed Porous Media for High Heat Flux Removal Exceeding 1000W/cm2

2009 ◽  
Author(s):  
Kazuhisa Yuki ◽  
Akira Matsui ◽  
Hidetoshi Hashizume ◽  
Koichi Suzuki
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Sink ◽  
Heat Transfer Performance ◽  
High Heat ◽  
Heat Sinks ◽  
High Heat Flux ◽  
Transfer Performance ◽  
Cooling Device ◽  
Fin Thickness

Heat transfer characteristics of micro-sized bronze particle-sintered porous heat sinks and copper minichannel-fins heat sinks are experimentally investigated in order to clarify the feasibility of a newly proposed micro/mini cooling device using fins-installed porous media. Regarding the porous heat sinks, fin effect toward more inside of the porous medium is promoted by sintering the porous heat sink on the heat transfer surface, which results in increasing the heat transfer performance up to 0.8MW/m2K at heat flux of 8.2MW/m2 though there still remains a large pressure loss issue. In addition, the results clarify that the heat exchanging area exists only in the vicinity of the heat transfer surface. As to the minichannel-fins heat sinks, the influence of the channel width and the fin thickness are evaluated in detail. As a result, the minichannel-fins heat sink having the narrower channel width (i.e. scale effect) and lower porosity (i.e. thicker fin thickness with larger heat capacity) achieves higher heat transfer performance up to 0.10MW/m2K at 8.3MW/m2. However, rapid increase of pressure loss, which is occasionally observed in a microchannel due to vapor bubbles choking the narrow channel, still remains as an issue under flow boiling conditions in the minichannel. Finally, heat transfer performance of the fin-installed porous heat sink is numerically predicted by the control volume method. The simulation confirms that the heat transfer coefficient at each wall superheat of 0 and 30 degrees has performance 2.5 times and 2.0 times higher than that of the normal fins, which indicates that this heat sink coupling the micro and mini channels has high potential as efficient cooling method under high heat flux conditions exceeding 10MW/m2.

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