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Thermal Management (thermal + management)

Distribution by Scientific Domains

Engineering	50%

Selected Abstracts

Copper-filled macroporous Si and cavity underneath for microchannel heat sink technology

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 11 2008
F. Zacharatos
Abstract Thermal management in ICs becomes essential as integration density and total power consumption increase. The use of microchannels in high power density electronics cooling is a well-known technique for heat transfer. In this work we developed Cu-filled macroporous Si channels with a Cu-filled cavity underneath, which may be used as heat sinks in high power density electronics cooling. Macroporous Si is formed by electrochemical dissolution of bulk Si, while pore filling with copper is achieved by electro-deposition. Using appropriate design, the resulting composite material may be fabricated on selected areas on the silicon substrate for use as heat sink on Si. The surface area is defined by patterning. The macroporous Si structure is composed of either randomly distributed pores or pores arranged in two-dimensional (2-D) arrays, fabricated by pre-patterning the Si surface before anodization so as to form pore initiation pits. The pore size in this work was 5,m, while the porous layer and the cavity underneath had both a thickness of 40 ,m. Copper deposition proceeds first by filling the micro-cavity underneath the porous layer. This is achieved by linearly increasing the applied potential during electro-deposition. After full Cu-filling of the cavity, pore filling starts from the bottom of each pore and proceeds laterally, while no nucleation takes place on pore wall. In this way, homogeneous copper wires within pores may be fabricated. The Cu/Si composite material is appropriate for forming channels with improved heat transfer within the Si wafer. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Along-channel mathematical modelling for proton exchange membrane fuel cells

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 12 2005
Wenbo Huang
Abstract Proper water and thermal management is essential for obtaining high performance of proton exchange membrane fuel cells (PEMFCs). A steady, two-dimensional water and thermal management model was developed, aiming at considering pressure effects (i.e. the effects of local pressure on the cell performance), pressure drop, open circuit voltage variation with stack temperature, water vapour effects on membrane conductivity, which made the model physically more reasonable and more suitable for various operating conditions. The model could predict the distributions of a series of important parameters along the flow channel, and thus the effects of various operating and design parameters on the fuel cell performance could be investigated easily by numerical trial-and-error method. The modelling results compared well with the available experimental results from the literatures. The results also showed that the humidification of both anode and cathode is crucial for the performance of PEMFCs. The model could be a very useful engineering tool for the optimization of PEMFCs. Copyright © 2005 John Wiley & Sons, Ltd. [source]

Enhancing thermal, electrical efficiencies of a miniature combustion-driven thermophotovoltaic system

PROGRESS IN PHOTOVOLTAICS: RESEARCH & APPLICATIONS, Issue 7 2009
Yueh-Heng Li
Abstract Methods to enhance the thermal and electrical efficiencies through novel design of combustion and thermal management of the combustor in a miniature thermophotovoltaic (TPV) system are proposed, discussed, and demonstrated in this paper. The miniature TPV system consists of a swirling combustor surrounded by GaSb PV cell arrays. The swirl combustor design, along with a heat-regeneration reverse tube and mixing-enhancing porous-medium fuel injection, improves the low illumination and incomplete combustion problems associated with typical miniature TPV systems. A reverse tube is used to enforce swirling flame attachment to the inner wall of the emitter by pushing the swirl recirculation zone back into the chamber and simultaneously redirecting the hot product gas for reheating the outer surface of the emitter. The porous medium fuel injector is used as a fuel/air mixing enhancer and as a flame stabilizer to anchor the flame. The miniature TPV system, using different combustor configurations, is tested and discussed. Results indicate that the proposed swirling combustor with a reverse tube and porous medium can improve the intensity and uniformity of the emitter illumination, and can increase the thermal radiant efficiency. Consequently, the overall thermal efficiency and electrical output of the miniature TPV system are greatly enhanced. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Enhanced energy efficiency and reliability of telecommunication equipment with the introduction of novel air cooled thermal architectures

BELL LABS TECHNICAL JOURNAL, Issue 2 2010
Domhnaill Hernon
In the past, thermal management was an afterthought in the design process of a product owing to the fact that heat dissipation loads and densities were minute and did not adversely affect component reliability. In fact, it may be stated that, historically, the sole purpose of thermal management was to ensure component operation below a critical temperature thereby providing reliable equipment operation for a given time period. However, this mindset has evolved in recent years given current economic and energy concerns. Climate change concern owing to vast green house gas emissions, increasing fuel and electricity costs, and a general trend towards energy-efficiency awareness has promoted thermal management to the forefront of "green" innovation within the information and communications technology (ICT) sector. If one considers the fact that up to 50 percent of the energy budget of a data center is spent on cooling equipment and that two percent of the United States' annual electricity is consumed by telecommunications equipment, it becomes obvious that thermal management has a key role to play in the development of eco-sustainable solutions. This paper will provide an overview of the importance of thermal management for reliable component operation and highlight the research areas where improved energy efficiency can be achieved. Novel air-cooled thermal solutions demonstrating significant energy savings and improved reliability over existing technology will be presented including three dimensional (3D) monolithic heat sinks and vortex generators. © 2010 Alcatel-Lucent. [source]