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In this research, we evaluate the potential for air cooling to meet the stringent cooling requirements of advanced automotive power electronics. We assess air cooling of power electronic components using laminar airflow micro-channel heat exchangers. Comparisons are made with ethylene glycol systems commonly used in tandem with engine cooling. Our analysis shows that despite a lower coefficient of...
In this study, confinement-driven boiling enhancement trends and experimental data from narrow parallel plate channels are presented and analyzed via comparison with numerical simulations of buoyancy-driven boiling and two phase flow using the commercially-available Fluent CFD software package. An Euler-Euler multiphase approach, known as the volume of fluid (VOF) method, is employed, as bubbles sizes...
Two-phase pumped-loop systems are being actively explored for the cooling of high-heat-flux electronics cooling because of their compactness and low thermal resistance. A typical two-phase pumped loop consists of a microchannel heat sink based evaporator, a finned-tube condenser, a reservoir, and a positive displacement pump. In the present study, the physics of operation of a two-phase pumped-loop...
This study compared thermal-hydraulic performance of a single-phase micro-pin-fin heat sink with that of a micro-channel heat sink having the same characteristic dimensions and operating under the same conditions. The objective was to explore the potential of micro-pin-fin heat sinks as an effective alternative to micro-channel heat sinks for dissipating high-heat-fluxes from small areas. The micro-pin-fin...
microchannel heat sinks are considered a strong candidate for meeting the increasing cooling needs of high-power microprocessors of today and the significant future. Such heat sinks are capable of dissipating impressive amounts of energy, as a result of high attainable heat transfer and favorable heat transfer surface area to volume ratios. The majority of microchannel heat sink studies performed...
This study examines the cooling performance of two hybrid cooling schemes that capitalize upon the merits of both micro-channel flow and jet impingement to achieve the high cooling fluxes and uniform temperatures demanded by advanced defense electronics. The jets supply HFE 7100 liquid coolant gradually into each micro-channel. The cooling performances of two different jet configurations, a series...
For a given heat sink thermal resistance and ambient temperature, the temperature of an electronic device rises fairly linearly with increasing device heat flux. This relationship is especially problematic for defense electronics, where heat dissipation is projected to exceed 1000 W/cm2 in the near future. Direct and indirect low temperature refrigeration cooling facilitate appreciable reduction in...
Chip-level heat flux levels have risen beyond 250 W/cm2 due to the presence of circuit architecture-driven hot-spots. After intense scrutiny over the past two decades, microchannel heat sinks are closer to commercial implementation as evidenced by the advent of the single-chip silicon cooler announced recently by IBM. Though there are a multitude of studies and data related to multichannel configurations,...
Boiling in microchannel heat sinks is attractive for high-performance electronics cooling due to the high heat transfer rates that can be achieved. However, the physics of flow boiling in microchannels, the flow patterns present, and the effect of microchannel size on the boiling regimes have not been investigated extensively, particularly with dielectric fluids. In the present work, experiments are...
The merits of water-fed microchannel heat sinks have shown that the technology may be a plausible and effective cooling solution for the ever-increasing power dissipation of high speed microprocessors. Favorable factors such as high heat transfer surface area and heat flux removal for reasonable operating pressures, as well small heat sink mass and volume continue to drive the technology. However,...
In order to enhance measurement accuracy, a gas mass flow sensor integrated with micro channels is proposed in this paper. The uniqueness of this flow sensor is that there is thermal convection effect on two sides of diaphragm, which results in a more sensitive temperature distribution. The temperature characteristics of the novel flow sensor are simulated at different flow rates, and the optimization...
Integrating microchannels at the thermal interfaces of heat sinks, spreaders, and microprocessor chips can reduce bond line thickness, assembly pressure, and overall thermal resistance. The channels help control the flow of particle-filled thermal interface materials (TIM) during the assembly squeeze but the relationship between channel geometry, material properties, and interfacial area is not fully...
Micropumps that can be directly integrated into microelectronic devices or microchannel heat sinks are of great interest due to performance, reliability, packaging and cost issues. One alternative is to generate the required flow directly in the microfluidic channels by inducing strong electromechanical forces in the fluid using integrated microelectrodes. In this work, a novel microfluidic pumping...
The ability to control mixing of reagents in MEMS systems is crucial for many biological and chemical analysis applications. However mixing in these microfluidic devices is a challenge because the flows are laminar corresponding to very low Reynolds number. In this paper, mixing of two aqueous reagents is studied in a "tau" shaped microchannel by means of computational fluid dynamics (CFD)...
This study examines the heat transfer enhancement attributes of carbon nanotubes (CNTs) applied to the bottom wall of a shallow rectangular micro-channel. Using deionized water as working fluid, experiments were performed with both a bare copper bottom wall and a CNT-coated copper wall. Boiling curves were generated for both walls, aided by high-speed video analysis of interfacial features. CNT arrays...
Microgap coolers provide direct contact between chemically inert, dielectric fluids and the back surface of an active electronic component, thus eliminating the significant interface thermal resistance associated with thermal interface materials and/or solid-solid contact between the component and a microchannel cold plate. This study focuses on the two-phase thermo-fluid characteristics of a dielectric...
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