Experiments on the transient heat transfer of minichannel heat sink under high heat flux density in an enclosed loop

2010 ◽  
Vol 34 (8) ◽  
pp. 1409-1414 ◽  
Author(s):  
Zhiqiang Zhou ◽  
Xianghua Xu ◽  
Xingang Liang
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flux Density ◽  
Heat Sink ◽  
Heat Flux Density ◽  
High Heat ◽  
Transient Heat Transfer ◽  
High Heat Flux

Numerical Study of Turbulent Heat Transfer and Pressure Drop Characteristics in a Water-Cooled Minichannel Heat Sink

2006 ◽  
Vol 129 (3) ◽  
pp. 247-255 ◽  
Author(s):  
X. L. Xie ◽  
W. Q. Tao ◽  
Y. L. He
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Pressure Drop ◽  
Wall Thickness ◽  
Heat Sink ◽  
Channel Wall ◽  
High Heat ◽  
Coolant Fluid ◽  
High Heat Flux ◽  
It Industry

With the rapid development of the Information Technology (IT) industry, the heat flux in integrated circuit (IC) chips cooled by air has almost reached its limit at about 100W∕cm2. Some applications in high technology industries require heat fluxes well beyond such a limitation. Therefore, the search for a more efficient cooling technology becomes one of the bottleneck problems of the further development of the IT industry. The microchannel flow geometry offers a large surface area of heat transfer and a high convective heat transfer coefficient. However, it has been hard to implement because of its very high pressure head required to pump the coolant fluid through the channels. A normal channel size could not give high heat flux, although the pressure drop is very small. A minichannel can be used in a heat sink with quite a high heat flux and a mild pressure loss. A minichannel heat sink with bottom size of 20mm×20mm is analyzed numerically for the single-phase turbulent flow of water as a coolant through small hydraulic diameters. A constant heat flux boundary condition is assumed. The effect of channel dimensions, channel wall thickness, bottom thickness, and inlet velocity on the pressure drop, temperature difference, and maximum allowable heat flux are presented. The results indicate that a narrow and deep channel with thin bottom thickness and relatively thin channel wall thickness results in improved heat transfer performance with a relatively high but acceptable pressure drop. A nearly optimized structure of heat sink is found that can cool a chip with heat flux of 350W∕cm2 at a pumping power of 0.314W.

scholarly journals The Process Characteristics of Rapid Freezing: Continuous and Discrete Heat Removal Method

2019 ◽  
Vol 49 (1) ◽  
pp. 104-112
Author(s):  
Евгений Неверов ◽  
Evgeniy Neverov ◽  
Людмила Лифенцева ◽  
Lyudmila Lifenceva ◽  
Андрей Усов ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flux Density ◽  
Heat Sink ◽  
Heat Flux Density ◽  
Meat Products ◽  
Freezing Process ◽  
Rapid Freezing ◽  
Process Characteristics ◽  
Continuous Heat

The research features the rational conditions of the process of rapid freezing for unpackaged small-sized foods by the method of continuous and discrete heat sink. The paper presents a graphical interpretation of the calculations of the average volume temperature for various temperature regimes that are used to freeze semi-finished products. The method makes it possible to determine the temperature at any time. The experiment defined the most rational range of air circulation speeds with a continuous heat sink in the range from 4 m/s to 6 m/s. The article features curves of changes in temperature and heat flux density during the rapid freezing of small-sized semi-finished meat products. They show the nature of the changes in the air coefficient of the meat sample heat transfer curves and the medium velocity of the object air. An increase in the heat flux density and a reduction in the duration of freezing by about 1.4 times occurred when the temperature of the cooling medium decreased from –20°C to – 40°C at an air speed of 6 m/s. The research determined the process characteristics of rapid freezing in continuous mode using a discrete heat sink. The authors describe the comparative characteristics of the change in the duration of the freezing process and the speed of the process with continuous and discrete heat sinks. The study presents the curves of changes in temperature and heat flux density during rapid freezing of small-sized semi-finished meat products, depending on the conditions of heat transfer. When a discrete heat sink was used, the duration of the freezing process was fpund to be 20 min, while with a continuous heat sink it lasted 26 min. The paper also includes a thermogram and the kinetics of heat sink during freezing in discrete conditions, as well as a software program for quick freezing of semi-finished minced meat products. The indicators of the meat quality are considered depending on the conditions of the heat sink, as well as the change in the physicochemical properties of the product after freezing and during storage. Studies of quality indicators of small-sized semi-finished meat products were carried out in the laboratory of the scientific-innovative enterprise “Sibagropererabotka” (Novosibirsk, Russia).

Heat Transfer and Hydraulic Characteristics of Cooling Water in a Flat Plate Heat Sink for High Heat Flux IGBT

2016 ◽  
Author(s):  
Chang-Nian Chen ◽  
Ji-Tian Han ◽  
Wei-Ping Gong ◽  
Tien-Chien Jen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Flat Plate ◽  
Heat Sink ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Hydraulic Characteristics ◽  
Flow Rates ◽  
Plate Heat

High heat flux is very dangerous for electronic heat transfer, such as IGBT (Insulated Gate Bipolar Transistor) cooling. In order to explore and master the heat transfer and hydraulic characteristics for IGBT cooling, experiments have been carried out to study the situation mentioned above in a flat plate heat sink, which was designed for high heat flux IGBT cooling. The geometrical parameters of the test section are as follows: outline dimension 229 mm × 124 mm × 30 mm; flow channels of 229 mm × 3 mm × 4 mm in total of 20. The experiments performed at atmospheric pressure and with inlet temperatures of 25–35°C, heat fluxes of 3.5–18.9 kW/m2. The influence of temperatures, heat fluxes on IGBT surface temperature and the cooling effect of the liquid cold plate have been investigated under a range of flow rates of 280–2300 kg/m2s. It was found that the heat transfer enhancement was very obvious using this kind of small sized channel for IGBT cooling, which was tens of times of the effect than air cooling or triple of the effect than that in normal sized channels. And the heat transfer enhancement increases with increasing heat fluxes and flow rates, while it decreases with increasing inlet temperatures. Most of the experimental results show good cooling effect as expected. However, it is dangerous for the cooling system under high heat fluxes when the system starts or stops suddenly, when the Respond Time (RT) is less than 5 seconds to cut off heated power. Also, the cooling performance is bad when the heat fluxes increased greatly, which is considered as abnormal situation in operating. The effect on IGBT surface temperature of heat flux is more obvious when the average Nusselt Number is smaller. For hydraulic characteristics observed, it was found that the flow friction increased with flow rates increasing, but the pressure drops of heated flow channels ahead were slightly larger than those back, especially under large flow rates conditions. That is because the temperatures of flow heated in channels ahead are lower than those back, which causes the fluid viscosity to be higher. At last, this paper suggested a series of method for enhancing heat transfer in flat plate heat sink, and also gave some ways to avoid heat transfer dangerous situations for IGBT cooling, which can provide a basis for thermodynamic and hydraulic calculation of flat plate heat sink design and lectotype.

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.

Fast Transient and Intensified Heat Dissipation Applicable to High Heat Flux Density

2011 ◽  
Author(s):  
Jing Li ◽  
Shuanshi Fan ◽  
Zemin Yao ◽  
Jing Li ◽  
Xinli Wei
Keyword(s):  
Heat Flux ◽  
Flux Density ◽  
Heat Flux Density ◽  
Heat Dissipation ◽  
Electronic Devices ◽  
Spray Cooling ◽  
High Heat ◽  
High Heat Flux ◽  
Power Electronic ◽  
Fast Transient

In this paper, in order to solve the problem of intensified heat dissipation in high power electronic devices, a fast transient and intensified heat dissipation technology was put forward by comparing many heat transfer modes based on the analytical study on the existing technologies about heat dissipation at high heat flux density and about fast heat transport. This technology combined spray cooling technology with fast endothermic chemical reaction processes; we summarized the characteristics of media applicable to an environment with transient high heat flux density by comparing various parameters of many sprayed media in the spray cooling process. According to the energy balance of endothermic chemical reactions of relevant media, we determined the media (mainly carbon dioxide hydrate) applicable to the fast transient and intensified heat dissipation technology and presented the conditions for the chemical reactions. We analyzed the methods controlling the instantaneous chemical reaction rate and proposed the structural characteristics of the chemical reactor so as to ensure that the time for heat removal will be control to around 0.01 second. Thus, the problem of fast transient heat dissipation in high power electronic devices, etc. would be radically solved.

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