scholarly journals Influence of the ambient temperature on the cooling efficiency of the high performance cooling device with thermosiphon effect

2018 ◽  
Vol 180 ◽  
pp. 02073
Author(s):  
Patrik Nemec ◽  
Milan Malcho
Keyword(s):  
Ambient Temperature ◽  
High Performance ◽  
Convection Heat Transfer ◽  
Heat Removal ◽  
Measuring Method ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Cooling Efficiency ◽  
Cooling Device

This work deal with experimental measurement and calculation cooling efficiency of the cooling device working with a heat pipe technology. The referred device in the article is cooling device capable transfer high heat fluxes from electric elements to the surrounding. The work contain description, working principle and construction of cooling device. The main factor affected the dissipation of high heat flux from electronic elements through the cooling device to the surrounding is condenser construction, its capacity and option of heat removal. Experimental part describe the measuring method cooling efficiency of the cooling device depending on ambient temperature in range -20 to 40°C and at heat load of electronic components 750 W. Measured results are compared with results calculation based on physical phenomena of boiling, condensation and natural convection heat transfer.

Dependence of Heat Transfer Coefficient on Porous Structure in Porous Media

2008 ◽  
Author(s):  
Akira Matsui ◽  
Kazuhisa Yuki ◽  
Hidetoshi Hashizume
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Porous Media ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
High Performance ◽  
Heat Removal ◽  
High Heat ◽  
Metal Foams ◽  
High Heat Flux

Detailed heat transfer characteristics of particle-sintered porous media and metal foams are evaluated to specify the important structural parameters suitable for high heat removal. The porous media used in this experiment are particle-sintered porous media made of bronze and SUS316L, and metal foams made of copper and nickel. Cooling water flows into the porous medium opposite to heat flux input loaded by a plasma arcjet. The result indicates that the bronze-particle porous medium of 100μm in pore size shows the highest performance and achieves heat transfer coefficient of 0.035MW/m2K at inlet heat flux 4.6MW/m2. Compared with the heat transfer performance of copper fiber-sintered porous media, the bronze particlesintered ones give lower heat transfer coefficient. However, the stable cooling conditions that the heat transfer coefficient does not depend on the flow velocity, were confirmed even at heat flux of 4.6MW/m2 in case of the bronze particle-sintered media, while not in the case of the copper-fiber sintered media. This signifies the possibility that the bronze-particle sintered media enable much higher heat flux removal of over 10MW/m2, which could be caused by higher permeability of the particle-sintered pore structures. Porous media with high permeability provide high performance of vapor evacuation, which leads to more stable heat removal even under extremely high heat flux. On the other hand, the heat transfer coefficient of the metal foams becomes lower because of the lower capillary and fin effects caused by too high porosity and low effective thermal conductivity. It is concluded that the pore structure having high performance of vapor evacuation as well as the high capillary and high fin effects is appropriate for extremely high heat flux removal of over 10MW/m2.

Laminar Flow Forced Convection Heat Transfer Behavior of Phase Change Material Fluid in Microchannels With Staggered Pins

2010 ◽  
Author(s):  
Satyanarayana Kondle ◽  
Jorge L. Alvarado ◽  
Charles Marsh ◽  
Gurunarayana Ravi
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Phase Change ◽  
Single Phase ◽  
Convection Heat Transfer ◽  
Heat Removal ◽  
High Heat ◽  
High Heat Flux ◽  
Small Areas ◽  
Phase Fluid

Microchannels have been extensively studied for electronic cooling applications ever since they were found to be effective in removing high heat flux from small areas. Many configurations of microchannels have been studied and compared for their effectiveness in heat removal. However, there is little data available in the literature on the use of pins in microchannels. Staggered pins in microchannels have higher heat removal characteristics because of the continuous breaking and formation of the boundary layer, but they also exhibit higher pressure drop because pins act as flow obstructions. This paper presents numerical results of two characteristic staggered pins (square and circular) in microchannels. The heat transfer performance of a single phase fluid in microchannels with staggered pins, and the corresponding pressure drop characteristics are also presented. An effective specific heat capacity model was used to account for the phase change process of PCM fluid. Comparison of heat transfer characteristics of single phase fluid and PCM fluid are made for two pins geometries for three different Reynolds numbers. Circular pins were found to be more effective in terms of heat transfer by exhibiting higher Nusselt number. Circular pin microchannels were also found to have lower pressure drop compared to the square pin microchannels.

Experimental Characterization of Two-Phase Cooling of Power Electronics in Thermosiphon and Forced Convection Modes

2021 ◽  
Vol 143 (3) ◽  
Author(s):  
Fabio Battaglia ◽  
Farah Singer ◽  
David C. Deisenroth ◽  
Michael M. Ohadi
Keyword(s):  
Heat Flux ◽  
Thermal Resistance ◽  
Power Electronics ◽  
Forced Convection ◽  
Heat Removal ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Two Phase ◽  
Total Thermal Resistance

Abstract In this paper, we present the results of an experimental study involving low thermal resistance cooling of high heat flux power electronics in a forced convection mode, as well as in a thermosiphon (buoyancy-driven) mode. The force-fed manifold microchannel cooling concept was utilized to substantially improve the cooling performance. In our design, the heat sink was integrated with the simulated heat source, through a single solder layer and substrate, thus reducing the total thermal resistance. The system was characterized and tested experimentally in two different configurations: the passive (buoyancy-driven) loop and the forced convection loop. Parametric studies were conducted to examine the role of different controlling parameters. It was demonstrated that the thermosiphon loop can handle heat fluxes in excess of 200 W/cm2 with a cooling thermal resistance of 0.225 (K cm2)/W for the novel cooling concept and moderate fluctuations in temperature. In the forced convection mode, a more uniform temperature distribution was achieved, while the heat removal performance was also substantially enhanced, with a corresponding heat flux capacity of up to 500 W/cm2 and a thermal resistance of 0.125 (K cm2)/W. A detailed characterization leading to these significant results, a comparison between the performance between the two configurations, and a flow visualization in both configurations are discussed in this paper.

Design of Practical Liquid Metal Cooling Device for Heat Dissipation of High Performance CPUs

2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Yueguang Deng ◽  
Jing Liu
Keyword(s):  
Heat Flux ◽  
Liquid Metal ◽  
Thermal Resistance ◽  
High Performance ◽  
Heat Dissipation ◽  
High Heat ◽  
High Heat Flux ◽  
Water Cooling ◽  
Cooling Device ◽  
Liquid Metal Cooling

Broad societal needs have focused attention on technologies that can effectively dissipate huge amount of heat from high power density electronic devices. Liquid metal cooling, which has been proposed in recent years, is fast emerging as a novel and promising solution to meet the requirements of high heat flux optoelectronic devices. In this paper, a design and implementation of a practical liquid metal cooling device for heat dissipation of high performance CPUs was demonstrated. GaInSn alloy with the melting point around 10°C was adopted as the coolant and a tower structure was implemented so that the lowest coolant amount was used. In order to better understand the design procedure and cooling capability, several crucial design principles and related fundamental theories were demonstrated and discussed. In the experimental study, two typical prototypes have been fabricated to evaluate the cooling performance of this liquid metal cooling device. The compared results with typical water cooling and commercially available heat pipes show that the present device could achieve excellent cooling capability. The thermal resistance could be as low as 0.13°C/W, which is competitive with most of the latest advanced CPU cooling devices in the market. Although the cost (about 70 dollars) is still relatively high, it could be significantly reduced to less than 30 dollars with the optimization of flow channel. Considering its advantages of low thermal resistance, capability to cope with extremely high heat flux, stability, durability, and energy saving characteristic when compared with heat pipe and water cooling, this liquid metal cooling device is quite practical for future application.

Forced Convection Boiling in Microchannels for Improved Heat Transfer

2006 ◽  
Author(s):  
Thomas B. Baummer ◽  
Ebrahim Al-Hajri ◽  
Michael M. Ohadi ◽  
Serguei V. Dessiatoun
Keyword(s):  
Heat Transfer ◽  
Aspect Ratio ◽  
Heat Removal ◽  
High Heat ◽  
Heat Fluxes ◽  
Working Fluid ◽  
High Heat Flux ◽  
Surface Areas ◽  
Feed Pressure ◽  
Wide Range

This paper presents experimental results from research investigating the heat transfer capabilities of microchannel surfaces using a novel force-fed boiling and evaporation technique. The evaporative surfaces being investigated consist of a series of parallel, high-aspect ratio, open topped microchannels. The different sample surfaces vary in channel density, channel aspect ratio, and channel width and have heat transfer surface areas up to ten times their nominal surface areas. Liquid enters the channels of the evaporative surface from above through a developed system of feed channels. This method organizes a liquid-vapor circulation at the boiling surface that results in dissipation of very high heat fluxes in the boiling/thin film evaporation mode. By using the force-fed boiling technique, nominal area heat transfer rates of 100,000 W/m2-K have been achieved with HFE-7100 as the working fluid [1]. In force-fed boiling, the many very short microchannels are working in parallel; therefore the feed pressure and pumping power are very low. This technique may prove valuable to a wide range of heat transfer applications, particularly for heat removal at high heat flux surfaces.

Reliability Challenges in Design and Operation of High Heat Powered Processors

2005 ◽  
Author(s):  
Ali Heydari ◽  
Vadim Gektin
Keyword(s):  
Heat Flux ◽  
Closed Loop ◽  
Heat Removal ◽  
High Heat ◽  
Electrical Signal ◽  
Open Loop ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Air Cooling ◽  
Interconnect Design

Advances in processor design have been made possible in part by increases in the packaging density of electronics. At the same time, combination of increased power dissipation and packaging density has led to substantial growth in the chip and system heat fluxes and amplified complexity in electrical signal integrity and mechanical stack-up design in the recent years, particularly, in the high-end computers. With the trend towards miniaturization, heat removal, along with increased reliability requirements, has become a major bottleneck in product development, especially, in low profile systems, telecom servers and blades. Cooling of high heat flux components may require consideration of innovative open-loop, as well as plausible closed-loop, cooling designs for data centers. This paper addresses reliability aspects of thermal, electrical, mechanical, and interconnect design and long-life operation of high-end air-cooling, as well as feasible active open and closed-loop cooling technologies of high heat flux processors.

Development of a High Performance Vapor Chamber for High Heat Flux Applications

2008 ◽  
Author(s):  
Yuan Zhao ◽  
Chung-Lung Chen
Keyword(s):  
Heat Flux ◽  
High Performance ◽  
Experimental Tests ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Vapor Chamber ◽  
Porous Network ◽  
Heat Spreader ◽  
Wick Structure

This paper introduces a high performance vapor chamber heat spreader with a novel bi-dispersed wick structure. The main wick structure is a sintered porous network in a latticed pattern, which contains not only small pores to transport liquid by capillary forces, but also many slots to provide large passages to vent vapor from heated surfaces. The copper particles have a diameter of approximately 50 μm; they produce an effective pore radius of approximately 13 μm after sintering. The slots have a typical width of approximately 500 μm. Unlike traditional bi-dispersed wick structures, the latticed wick structures provide undisrupted liquid delivery passages and vapor escape channels and thus greatly improve the heat transfer performance. Preliminary experimental tests were conducted and the results were analyzed. It was shown by the experiments that vapor chamber heat spreaders with the latticed wicks present three times improvement on heat spreading performance, comparing with a solid copper heat spreader, and much improved capacity to handle hot spots with local heat fluxes exceeding 300 W/cm2, which will have great impacts on extending heat pipe technology from traditional low to medium heat fluxes to high heat flux applications.

STABLE, CALM, AND HIGH-HEAT-FLUX HEAT REMOVAL USING A POROUS-MICRO-CHANNEL

2017 ◽  
Author(s):  
Tomio Okawa ◽  
Junki Ohashi ◽  
Ryo Hirata ◽  
Koji Enoki
Keyword(s):  
Heat Flux ◽  
Heat Removal ◽  
High Heat ◽  
High Heat Flux ◽  
Micro Channel

Thermo-Fluid-Stress-Deformation Analysis of Two-Layer Microchannels for Cooling Chips With Hot Spots

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Abas Abdoli ◽  
George S. Dulikravich ◽  
Genesis Vasquez ◽  
Siavash Rastkar
Keyword(s):  
Heat Flux ◽  
Thermal Stresses ◽  
Hot Spot ◽  
Heat Removal ◽  
High Heat ◽  
Heat Transfer Analysis ◽  
Deformation Analysis ◽  
High Heat Flux ◽  
Cooling Design ◽  
Microchannel Cooling

Two-layer single phase flow microchannels were studied for cooling of electronic chips with a hot spot. A chip with 2.45 × 2.45 mm footprint and a hot spot of 0.5 × 0.5 mm in its center was studied in this research. Two different cases were simulated in which heat fluxes of 1500 W cm−2 and 2000 W cm−2 were applied at the hot spot. Heat flux of 1000 W cm−2 was applied on the rest of the chip. Each microchannel layer had 20 channels with an aspect ratio of 4:1. Direction of the second microchannel layer was rotated 90 deg with respect to the first layer. Fully three-dimensional (3D) conjugate heat transfer analysis was performed to study the heat removal capacity of the proposed two-layer microchannel cooling design for high heat flux chips. In the next step, a linear stress analysis was performed to investigate the effects of thermal stresses applied to the microchannel cooling design due to variations of temperature field. Results showed that two-layer microchannel configuration was capable of removing heat from high heat flux chips with a hot spot.

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.

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