Considerations and Challenges for Large Area Embedded Micro-channels with 3D Manifold in High Heat Flux Power Electronics Applications

2020 ◽  
Author(s):  
Alisha Piazza ◽  
Sougata Hazra ◽  
Ki Wook Jung ◽  
Michael Degner ◽  
Man Prakash Gupta ◽  
...  
Keyword(s):  
Heat Flux ◽  
Power Electronics ◽  
High Heat ◽  
High Heat Flux ◽  
Large Area ◽  
Micro Channels

Development of Advanced High Heat Flux Cooling System for Power Electronics

2009 ◽  
Author(s):  
Yasuhisa Shinmoto ◽  
Shinichi Miura ◽  
Koichi Suzuki ◽  
Yoshiyuki Abe ◽  
Haruhiko Ohta
Keyword(s):  
Heat Flux ◽  
Power Electronics ◽  
Critical Heat Flux ◽  
Heating Surface ◽  
Narrow Channel ◽  
High Heat ◽  
High Heat Flux ◽  
Gap Size ◽  
Narrow Channels ◽  
Very High

Recent development in electronic devices with increased heat dissipation requires severe cooling conditions and an efficient method for heat removal is needed for the cooling under high heat flux conditions. Most researches are concentrated on small semiconductors with high heat flux density, while almost no existing researches concerning the cooling of a large semiconductor, i.e. power electronics, with high heat generation density from a large cooling area. A narrow channel between parallel plates is one of ideal structures for the application of boiling phenomena which uses the cooling for such large semiconductors. To develop high-performance cooling systems for power electronics, experiments on increase in critical heat flux (CHF) for flow boiling in narrow channels by improved liquid supply was conducted. To realize the cooling of large areas at extremely high heat flux under the conditions for a minimum gap size and a minimum flow rate of liquid supplied, the structure with auxiliary liquid supply was devised to prevent the extension of dry-patches underneath flattened bubbles generated in a narrow channel. The heating surface was experimented in two channels with different dimensions. The heating surfaces have the width of 30mm and the lengths of 50mm and 150mm in the flow direction. A large width of actual power electronics is realizable by the parallel installation of the same channel structure in the transverse direction. The cooling liquid is additionally supplied via sintered metal plates from the auxiliary unheated channels located at sides or behind the main heated channel. To supply the liquid to the entire heating surface, fine grooves are machined on the heating surface for enhance the spontaneous liquid supply by the aid of capillary force. The gap size of narrow channels are varied as 0.7mm, 2mm and 5mm. Distribution of liquid flow rate to the main heated channel and the auxiliary unheated channels were varied to investigate its effect on the critical heat flux. Test liquids employed are R113, FC72 and water. The systematic experiments by using water as a test liquid were conducted. Critical heat flux values larger than 2×106W/m2 were obtained at both gap sizes of 2mm and 5mm for a heated length of 150mm. A very high heat transfer coefficient as much as 1×105W/m2K was obtained at very high heat flux near CHF for the gap size of 2mm. This paper is a summary of experimental results obtained in the past by the present authors.

Integrated Vapor Chamber Heat Spreader for Power Module Applications

2017 ◽  
Author(s):  
Clayton L. Hose ◽  
Dimeji Ibitayo ◽  
Lauren M. Boteler ◽  
Jens Weyant ◽  
Bradley Richard
Keyword(s):  
Heat Flux ◽  
Thermal Resistance ◽  
Power Electronics ◽  
Coefficient Of Thermal Expansion ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Vapor Chamber ◽  
Power Module ◽  
Heat Spreader

This work presents a demonstration of a coefficient of thermal expansion (CTE) matched, high heat flux vapor chamber directly integrated onto the backside of a direct bond copper (DBC) substrate to improve heat spreading and reduce thermal resistance of power electronics modules. Typical vapor chambers are designed to operate at heat fluxes > 25 W/cm2 with overall thermal resistances < 0.20 °C/W. Due to the rising demands for increased thermal performance in high power electronics modules, this vapor chamber has been designed as a passive, drop-in replacement for a standard heat spreader. In order to operate with device heat fluxes >500 W/cm2 while maintaining low thermal resistance, a planar vapor chamber is positioned onto the backside of the power substrate, which incorporates a specially designed wick directly beneath the active heat dissipating components to balance liquid return and vapor mass flow. In addition to the high heat flux capability, the vapor chamber is designed to be CTE matched to reduce thermally induced stresses. Modeling results showed effective thermal conductivities of up to 950 W/m-K, which is 5 times better than standard copper-molybdenum (CuMo) heat spreaders. Experimental results show a 43°C reduction in device temperature compared to a standard solid CuMo heat spreader at a heat flux of 520 W/cm2.

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.

Micro Heat Changers and Surface-Micro-Coolers for High Heat Flux

2008 ◽  
Author(s):  
Ulrich Schygulla ◽  
Ju¨rgen J. Brandner ◽  
Eugen Anurjew ◽  
Edgar Hansjosten ◽  
Klaus Schubert
Keyword(s):  
Heat Flux ◽  
Heat Exchanger ◽  
Mass Flow ◽  
Pressure Loss ◽  
High Heat ◽  
Heat Fluxes ◽  
High Heat Flux ◽  
Micro Heat Exchanger ◽  
Micro Channels ◽  
Higher Temperature

This publication describes the development of a new microstructure to transfer high heat fluxes. With a simple mathematical model based on heat conduction theory for the heat transfer in a micro channel at laminar flow conditions it was deduced that for the transmission of high heat fluxes only the initial part at the beginning of the micro channels is of importance, i.e. the micro channels should be short. Based on this principle a micro structure was designed with a large number of short micro channels taken in parallel. With this newly developed microstructure a prototype of a micro heat exchanger and a surface micro cooler was manufactured and tested. Using the prototype of the micro heat exchanger, manufactured of plastic, heat fluxes up to 500 W/cm2 were achieved at a pressure loss of 0.16 MPa and a mass flow of the water of 200 kg/h per passage. Due to the use of materials with a higher temperature resistance and higher stability like aluminum or ceramic, higher water throughputs and higher flow velocities could be realized in the micro channels. Thus it was possible to increase the heat flux up to approx. 800 W/cm2 at a pressure loss of approx. 0.35 MPa and a mass flow of 350 kg/h per passage. The important focus of investigation of the surface micro cooler was set on the examination of the surface temperatures for different heat fluxes and different velocities of the water in the micro channels. The experimental results of these surface micro coolers are summarized to characteristic maps. With this characteristic maps it is possible to determine whether a micro surface cooler can be used for a specific application.

Experimental study of thermal limits with one-side heated smooth channel for plasma facing component safety

2021 ◽  
Author(s):  
Ji Hwan Lim ◽  
Minkyu Park
Keyword(s):  
Heat Flux ◽  
Flow Instability ◽  
Load Condition ◽  
High Heat ◽  
Error Rates ◽  
Thermal Engineering ◽  
High Heat Flux ◽  
System Pressure ◽  
Smooth Channel ◽  
Micro Channels

Abstract In order to stably operate the equipment inside the tokamak, which is loaded with a heat flux of several MW/m2 under the one-side heating condition, it is necessary to thoroughly prepare for various thermal engineering limits that may occur under the high heat flux load condition. In this study, we have experimentally explored critical heat flux (CHF) and onset of flow instability (OFI), which are considered potential threats in a DEMO fusion power plant. Specifically, the effect of system parameters on CHF was investigated. The results indicate that with an increase in subcooling and mass flux, the CHF increased, as it induced a faster bubble condensation near the CHF. As the system pressure increased, the CHF also increased. This is because the bubble size reduction effect was dominant in the pressure range of 1–10 bar. Most of the existing CHF correlations could evaluate the CHF with reasonable accuracy of within 25%; especially, the Boscary CHF correlation yielded the highest accuracy with an average error of 12%. Similar to CHF, OFI, which is a measure of the sudden fluctuations in the system pressure caused by a large amount of vapor generated due to the high heat flux, tended to increase as the subcooling, mass flow rate, and system pressure increased. Most of the existing OFI correlations yielded large error rates (more than 135%) as these correlations were primarily developed for micro-channels. Therefore, in this study, a new OFI correlation was developed using a Python code, in combination with an artificial intelligence (AI) regression method. The developed correlation can be used in the cooling system design of tokamaks, which involve a high-heat load condition on one-side of the reactor.

A Microstructure Device for Single Phase Surface Cooling

2011 ◽  
Author(s):  
Juergen J. Brandner ◽  
Natrah binti Kamaruzaman ◽  
Stefan Maikowske
Keyword(s):  
Heat Flux ◽  
Pressure Drop ◽  
Single Phase ◽  
High Heat ◽  
Theoretical Background ◽  
Test Facility ◽  
Fluid Distribution ◽  
High Heat Flux ◽  
Surface Cooling ◽  
Micro Channels

A microstructure device for cooling of hot surfaces at liquid single phase laminar flow is presented. The initial design as well as the theoretical background is described in detail. It consists of numerous short micro channels acting as overflow structures and providing a relatively large hydraulic diameter, used in parallel between large inlet and outlet channels. The design was chosen to be scalable as well as appropriate for mass production in different materials. The fluid distribution was optimized as well as the dimensions of the overflow structures in terms of heat transfer, both by CFD simulations. Several devices were tested. They provide very high heat flux at reasonably low pressure drop. The temperature difference to achieve, heat flux and pressure drop can be adjusted easily by control of the applied mass flow. The design was tested as liquid-liquid heat exchanger in a simple lab-scale test facility. Moreover, using a copper electrically powered surface heat focus, some devices were tested as surface coolers.

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