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In recent years, the demand for compute capability has increased rapidly, and data centers all over the world are consuming much more power than before. Data centers across the globe consume around 100 GWh and it is expected to increase by 30% by 2016. In 2012, the increase in data center energy consumption in the United States and China was 800MWh and 500MWh respectively, based on Forest & Sullivan...
A thermal model has been developed to simulate the performance of thermoelectric cooling for two avionics scenarios, where utilizing commercial off the shelf (COTS) components is highly desirable. Modeling predictions were validated through a series of experiments which studied the two scenarios at varying heat loads and heat sink thermal resistances. In these experiments, component temperatures were...
Generally, a porous jump model is used for rapid air flow simulations (without resolving the tile pore structure) through perforated tiles in data centers. The porous jump model only specifies a step pressure loss at the tile surface, without any influence on the flow field. However, in reality, the downstream flowfield is affected because of the momentum rise of air due to acceleration of air through...
Graphene and few-layer graphene reveal exceptionally high thermal conduction properties, which can be used for thermal management. Here we show that incorporation of graphene and few-layer graphene to the hydrocarbon-based phase change material allows one to increase its thermal conductivity by more than two orders of magnitude while preserving its latent heat storage ability. A combination of the...
Nowadays, thermal designers have to deal with sophisticated 3D component packaging, enclosing several chips or conventional individually-packaged Integrated circuits with various power densities, embedded in small volumes that will drive up the complexity of their thermal management.
Heat exchangers are important facilities used in data center cooling systems. The effectiveness of the heat exchangers strongly influences the thermal performance of the cooling systems. Rear door heat exchangers, in-row, overhead coolers and fully contained cabinets are some examples of executing liquid and hybrid cooling systems used in data centers. A liquid to liquid heat exchanger is an important...
In 2011 IBM announced the Power 775 Supercomputing node/system which, for the time, was a monumental leap forward in computing performance and energy efficiency. The system was designed from the start with water cooling in mind. The result: a system with greater than 95% of its heat load conducted directly to water and a system that, together with a rear door heat exchanger, removes 100% of its heat...
Complete immersion of servers in electrically nonconductive mineral oil has recently become a promising technique for minimizing cooling energy consumption in data centers. Liquid cooling in general offers significant advantages over traditional air cooling approaches due to the higher heat capacities of fluids. However, a lack of sufficient published data and long term reliability documentation of...
Packaging of optoelectronic devices becomes more and more challenging due to higher heat generation per unit volume. We experimentally investigated the packaging thermal resistance for a semiconductor laser device and compared results for two material alternatives for the electrical passivation layer. We used the time-resolved thermoreflectance technique to obtain the time response for the thermal...
Thermal and fluid behavior are governing factors for the via processing of semiconducting substrates. In order to investigate the fundamentals, nanosecond (ns) time-resolved visualization of ns-pulse Nd:YAG laser ablation of SiC substrate has been performed for various conditions. Time-resolved visualizations have been conducted by using a ultra high speed camera with the frame rate of 200 million...
The steady state method is a commonly used and in principle simple way to measure thermal resistance and conductivity of thermal interface materials (TIMs). The sample must be positioned between a hot and a cold plate with constant temperatures, whereby a heat flow through the sample and temperature gradient across the sample are generated. To determine the thermal resistance of the sample the heat...
The transient behavior of IT equipment can be represented by a lumped thermal capacitance for use in data center level transient thermal simulations. Previous work has proposed a mathematical methodology to extract the necessary lumped capacitance parameters, the server's time constant and heat transfer effectiveness, via air temperature measurements. This work describes and experimentally tests that...
Micro-electro-mechanical systems (MEMS) devices are used in a variety of applications for sensing acceleration, translation, rotation, pressure and sound in addition to actuation and signal generation. The MEMS devices have been applied to varied fields including healthcare and automotive applications. Data on reliability degradation of MEMS devices in harsh environment applications including combined...
With increasing power density in electronics packages/modules, thermal resistances at multiple interfaces are a bottleneck to efficient heat removal from the package. In this work, the performance of thermal interface materials such as grease, thermoplastic adhesives and diffusion-bonded interfaces are characterized using the phase-sensitive transient thermoreflectance technique. A multi-layer heat...
In this work dynamic numerical models for server, rack, and Computer Room Air Handler (CRAH) are developed and used in a room level Computational Fluid Dynamics (CFD) model. The effect of server, rack, and Computer Room Air Handler (CRAH) heat capacity is investigated in cases of server power fluctuations and CRAH failure situations.
The low contact angle hysteresis shown by superhydrophobic surfaces towards water has many interesting applications including condensation. However these useful properties can be lost during condensation. Water droplets randomly nucleate anywhere on the surface including in between the surface textures and grow while still remaining entrained in the texture. By using specially crafted textures, coalescence...
Air-water hybrid cooling offers flexible design choices for computer systems with components of different thermal management needs. On one hand, water cooling enables the continuous growth of CPU performance and increasing packaging density. High performance cold plates such as microchannels have been successfully implemented for water cooling in previous high-end systems. When coupled with an air-water...
In this study, as a passive energy conversion/transport device, the performance of a pulsating heat pipe (PHP) using nanofluid is experimentally investigated. It has been suggested that nanofluids could improve the performance of wickless self-sustaining heat pipes. The transparent fused quartz tubing with 3 mm diameter is used to visualize the oscillations within the adiabatic section of the pipe...
Insulated gate bipolar transistors are the power semiconductors used for high current applications as a switching device. It is widely used in electrical and hybrid vehicles. It has become increasingly important to understand the reliability of these modules. The lifetime prediction is based on the assumption that the solder interconnections are the weakest part of the module assembly and that the...
White light emitting diodes (LEDs) are appearing in general illumination applications. Clusters of such LEDs can replace an incandescent light bulb of equal luminosity on the merit of considerably low power consumption. However the optical performance and working life of these LED packages are strongly dependent on the temperature of the p-n junction of the LED. Hence it is very critical to determine...
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