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Design features and experimental results are presented for a heatsink with the thermo-siphon structure for cooling multi- chip modules. The prototype heatsink was made, which consists of copper tubes, stainless container, PF-5060 as a coolant and rubber heaters for simulating multi-chip modules, and some basic experiments were carried out to obtain the cooling performance of the heatsink with the...
For the reliable and continuous operation of humanoid robot, various types of multiple heat sources such as CPUs, motors, drivers should be cooled down by using compact and light-weight cooling devices. In this study, thermal performances of one metallic cold plate and two different types of non-metallic cold plates with a dielectric coolant (FC-72) as a working fluid are investigated in two-phase...
A tube-type evaporator requires capillary force in order to lift liquid refrigerant to circumference direction under a gravity field, which reduces thermal performance. Therefore, a capillary pumped loop with a plate-type evaporator was newly manufactured to improve the performance and reduce the thickness of the evaporator. The plate-type evaporator is flat disk shaped with an effective diameter...
An air cooled loop heat pipe (LHP) system was developed for cooling a dual CPU 1U server. The LHP uses newly developed flat plate evaporators and air cooled condensers with millimeter scale condensation channels and plain parallel fins. Bench tests were conducted using 20 x 20 mm uniform heat sources dissipating 100 watts and air preheating to simulate air-cooled operation within a 1U server chassis...
The ever-increasing size of wireless networks has led to the development of new base station architectures. Traditional telecommunication base stations have baseband and radio-frequency (RF) components mounted inside an air-conditioned hut with co-axial cables transmitting signals to remote antennas. The industry is moving to distributed network and remote radio head (RRH) architectures where the...
This paper is a follow-up of a hard disk drive study presented at ITherm 2006 on thermal-acoustic optimization of a HDD placed inside an air duct with an axial fan. Today we present a benchmark study performed on a number of consumer products containing a HDD. We will show that it is possible to predict if a certain application design is close to its optimal, set-level design. This is important for...
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...
Power dissipation levels in mobile electronics devices are heading towards five watts and above. With this power dissipation level, products such as mobile phones will require active cooling to ensure that the devices operate within an acceptable temperature envelop from both user comfort and reliability perspectives. To the authors knowledge no studies to date have been carried out to determine the...
This study examines numerically details of the flow and temperature fields of heat sinks with short plate fins cooled by impinging jet. The main focus is on the effect of fin shapes on the heat sink performance. Conjugate heat transfer between airflow convection and conduction inside the fin and base is considered. Three different shapes under study are rectangular, round-headed and elliptic, while...
Rapid development in the design of electronic packages for modern high-speed computers has led to the demand for effective methods of chip cooling. The primary concerns in thermal management applications are high thermal conductivity, large specific surface area and low weight. Graphite foams which possess predominantly spherical pores with smaller openings between the cells constitute a novel highly-conductive...
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...
A novel vapor chamber is proposed and tested in this study. Multi-layer copper mesh is sintered to the inner surface of the bottom plate as the evaporator wick. Parallel channels, with inter-channel openings, are made on the inner surface of the top plate. The peaks of the channel walls directly contact with the wick so that the channels function as vapor path, condenser and structural supporters...
Boiling heat transfer enhancement for a two-phase cooling design is presented in this paper. The paper discusses an effective method of boiling heat transfer enhancement and its performance. The pool boiling heat transfer from the silicon surface is enhanced by combination of surface modification and micro machined structure. The effect of micro structure features like pore diameter, pore pitch, channel...
Porous metal foams, inserted into the channels of a liquid cold plate, can be used to enhance forced convection and flow boiling heat transfer and may be especially useful for direct, dielectric liquid cooling of electronic and photonic components. This study explores the thermofiuid characteristics of three porous copper foam configurations: 95% porosity and 10 PPI, 95% porosity and 20 PPI, and 92%...
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...
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