State of the Art of Electronics Cooling for Radar Antenna Applications

2017 ◽  
Author(s):  
Girish Upadhya ◽  
Clayton Pullins ◽  
Karl Freitag ◽  
George Hall ◽  
James Marthinuss
Keyword(s):  
Heat Flux ◽  
Two Phase Flow ◽  
Electronic Device ◽  
High Heat ◽  
Thermal Design ◽  
High Heat Flux ◽  
Phase Flow ◽  
Two Phase ◽  
Modeling Tools ◽  
Radar Antenna

High heat flux from electronic devices remains a continuing challenge for cooling of electronics hardware in radar antenna applications pertaining to the defense industry. Cooling methods for such applications have varied from conduction cooling approaches for the cooling of circuit card assemblies, to advanced convection cooling using two phase flow (with pumped refrigerant) for the high heat flux devices used in transmit / receive modules. It is found that the limiting parameter in such applications is usually the heat flux from the electronic device. This paper provides an overview of the cooling techniques used for defense electronics, as well as current modeling tools and analytical methods used for thermal design during the product development phase. The role of thermal interface materials used in the material stack up for the thermal design solutions will also be touched upon. Additionally, the importance of using experimental techniques to characterize the heat transfer coefficient for the pumped refrigerant two phase flow will be discussed.

Numerical Investigation of Thermofluid Flow Characteristics With Phase Change Against High Heat Flux in Porous Media

2008 ◽  
Vol 130 (1) ◽  
Author(s):  
Kazuhisa Yuki ◽  
Jun Abei ◽  
Hidetoshi Hashizume ◽  
Saburo Toda
Keyword(s):  
Heat Flux ◽  
Solid Phase ◽  
Flow Characteristics ◽  
High Heat ◽  
High Heat Flux ◽  
Phase Flow ◽  
Two Phase ◽  
Thermal Nonequilibrium ◽  
Phase Mixture ◽  
Flow Case

This study numerically evaluates thermofluid flow characteristics in porous medium by a newly developed “modified two-phase mixture model” applying Ergun’s law and a two-energy model instead of a one-energy model. In a single-phase flow case, thermal nonequilibrium between a solid phase and a fluid phase is observed in the area where imposed heat conducts from a heating wall and further convective heat transfer is more active. The degree of thermal nonequilibrium has a positive correlation with the increase in flow velocity and heat flux input. In the case of two-phase flow, the thermal nonequilibrium is remarkable in the two-phase region because the solid-phase temperature in this region is far beyond saturation temperature. A difference between these two models is obvious especially in the two-phase flow case, so that the numerical simulation with the modified two-phase mixture model is indispensable under the high heat flux conditions of over 1MW∕m2.

A Review of Two-Phase Forced Cooling in Three-Dimensional Stacked Electronics: Technology Integration

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Craig Green ◽  
Peter Kottke ◽  
Xuefei Han ◽  
Casey Woodrum ◽  
Thomas Sarvey ◽  
...  
Keyword(s):  
Heat Flux ◽  
Heat Sink ◽  
Three Dimensional ◽  
High Heat ◽  
Heat Fluxes ◽  
Thermal Design ◽  
High Heat Flux ◽  
Two Phase ◽  
Forced Cooling ◽  
Fluidic Routing

Three-dimensional (3D) stacked electronics present significant advantages from an electrical design perspective, ranging from shorter interconnect lengths to enabling heterogeneous integration. However, multitier stacking exacerbates an already difficult thermal problem. Localized hotspots within individual tiers can provide an additional challenge when the high heat flux region is buried within the stack. Numerous investigations have been launched in the previous decade seeking to develop cooling solutions that can be integrated within the 3D stack, allowing the cooling to scale with the number of tiers in the system. Two-phase cooling is of particular interest, because the associated reduced flow rates may allow reduction in pumping power, and the saturated temperature condition of the coolant may offer enhanced device temperature uniformity. This paper presents a review of the advances in two-phase forced cooling in the past decade, with a focus on the challenges of integrating the technology in high heat flux 3D systems. A holistic approach is applied, considering not only the thermal performance of standalone cooling strategies but also coolant selection, fluidic routing, packaging, and system reliability. Finally, a cohesive approach to thermal design of an evaporative cooling based heat sink developed by the authors is presented, taking into account all of the integration considerations discussed previously. The thermal design seeks to achieve the dissipation of very large (in excess of 500 W/cm2) background heat fluxes over a large 1 cm × 1 cm chip area, as well as extreme (in excess of 2 kW/cm2) hotspot heat fluxes over small 200 μm × 200 μm areas, employing a hybrid design strategy that combines a micropin–fin heat sink for background cooling as well as localized, ultrathin microgaps for hotspot cooling.

Numerical Prediction of Cooling Capability in Hemispherical Gap Flow Passage for In-Vessel Core Retention

2002 ◽  
Author(s):  
Akihiro Uchibori ◽  
Kenji Fukuda ◽  
Koji Morita ◽  
Tatsuya Matsumoto
Keyword(s):  
Heat Flux ◽  
Void Fraction ◽  
Two Phase Flow ◽  
High Heat Flux ◽  
Phase Flow ◽  
Narrow Gap ◽  
Two Phase ◽  
Flow Passage ◽  
Drift Flux Model ◽  
Gap Flow

A numerical method for thermal hydraulic phenomena in a hemispherical narrow gap flow passage was developed to evaluate a cooling capability with gap formation between the molten core and the reactor pressure vessel.The gap cooling mechanism was modeled as gas-liquid two-phase flow in the narrow gap with two-dimensional spherical coordinate system. The analytical model is based on a modified drift flux model for multi-dimensional two-phase flow analysis. Numerical results showed that liquid phase intrusion into the gap in the counter direction of gas phase upward flow kept down a rise of void fraction as gap cooling phenomena. Under the high heat flux condition,expansion of the high void fraction region due to the counter-current flow limitation was reproduced as a dryout phenomenon. Characteristics of gap cooling limitation predicted by the numerical analyses were verified by comparison with various experimental data and correlations of critical heat flux.

scholarly journals Experimental Investigation of Non-Uniform Heating on Flow Boiling Instabilities in a Microchannels Based Heat Sink

2009 ◽  
Author(s):  
D. Bogojevic ◽  
K. Sefiane ◽  
A. J. Walton ◽  
H. Lin ◽  
G. Cummins ◽  
...  
Keyword(s):  
Heat Sink ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
High Heat ◽  
High Heat Flux ◽  
Phase Flow ◽  
Central Processor ◽  
Back Side ◽  
Uniform Heating ◽  
Two Phase

Two-phase flow boiling in microchannels is one of the most promising cooling technologies able to cope with high heat fluxes generated by the next generation of central processor units (CPU). If flow boiling is to be used as a thermal management method for high heat flux electronics it is necessary to understand the behaviour of a non-uniform heat distribution, which is typically the case observed in a real operating CPU. The work presented is an experimental study of two-phase boiling in a multi-channel silicon heat sink with non-uniform heating, using water as a cooling liquid. Thin nickel film sensors, integrated on the back side of the heat sinks were used in order to gain insight related to temperature fluctuations caused by two-phase flow instabilities under non-uniform heating. The effect of various hotspot locations on the temperature profile and pressure drop has been investigated, with hotspots located in different positions along the heat sink. It was observed that boiling inside microchannels with non-uniform heating led to high temperature non-uniformity in transverse direction.

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