wall Superheat Excursions in the Boiling incipience of Dielectric Fluids
TL;DR: In this paper, a brief review of the mechanisms that may be responsible for delayed nucleation and examines the limited literature on incipience superheat excursions is presented. But the authors do not consider the effect of temperature variations on the nucleation of microelectronic components.
Abstract: Many of the candidate fluids for immersion cooling of microelectronic components possess both low surface tension and high gas solubility. As a consequence, ebullient heat transfer with such fluids is accompanied by nucleation anomalies and a frequently observed wall temperature overshoot. The difficulty in preventing this thermal excursion and in predicting its magnitude constrains the development of immersion cooling systems. This paper begins with a brief review of the mechanisms that may be responsible for delayed nucleation and examines the limited literature on incipience superheat excursions.
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11 May 1988
TL;DR: In this article, it was demonstrated that the generation of vapor below a heated surface is an effective means of reducing the large superheat required for inception of boiling with liquids suitable for direct-immersion cooling of microelectronic devices.
Abstract: It is demonstrated that the generation of vapor below a heated surface is an effective means of reducing the large superheat required for inception of boiling with liquids suitable for direct-immersion cooling of microelectronic devices. In experiments with R-113 and a plain copper heat sink surface, the incipient boiling superheat was reduced from 33 K to as low as 8 K. With sintered boiling surfaces, the incipient boiling superheat was reduced from 22 K to as low as 7 K. A reasonable explanation for the effectiveness of this sparging technique is that the impacting bubbles activate temporarily dormant cavities that, in turn, activate large neighboring cavities. The technique appears to be easily adaptable to liquid incapsulated modules containing arrays of microelectronic devices such as chips. >
22 citations
TL;DR: First experimental evidence that the position of the active nucleation sites can be controlled through chemical patterning of smooth surfaces is shown: in this study, the heated surfaces are chemically grafted with alkylsilane self-assembled monolayers by microcontact printing.
Abstract: The onset of flow boiling of a liquid is linked to the superheat condition that is necessary to activate the nucleation sites on contacting surfaces. The nucleation sites are usually represented by cavities in the rough surface of the heat exchanger. On smooth surfaces, the region where bubble detachment does not occur due to the lack of superheating may constitute a serious limitation for microfluidic devices. This paper shows the first experimental evidence that the position of the active nucleation sites can be controlled through chemical patterning of smooth surfaces: in this study, the heated surfaces are chemically grafted with alkylsilane self-assembled monolayers by microcontact printing. The analysis of the propagation of the bubble zone area quantitatively shows that the bubbles remain localized on top of the grafted zone and that, in the initial phase of the experiment, the center of mass of the bubble zone only moves along the vertical axis, without lateral drift.
21 citations
Dissertation•
01 Jan 2006
21 citations
01 Jan 1994
TL;DR: In this paper, the theory and practice of direct liquid cooling of microelectronic components is discussed, and a morphological analysis is suggested for the classification of liquid-cooling concepts.
Abstract: The present work reviews the theory and practice of direct liquid cooling of microelectronic components. A morphological analysis is suggested for the classification of liquid-cooling concepts. While both immersion and microgroove cooling of chips are discussed, the emphasis is on immersion cooling. The performance of individual chips and liquid incapsulated modules, including the submerged condenser, is reviewed in detail, with data presented. Flow-through modules and falling-film techniques are also discussed. Finally, figures-of-merit for coolants are noted.
20 citations
11 May 1988
TL;DR: The thermal aspects of an immersion-cooled computer designed to operate at cryogenic temperatures are discussed in detail in this paper, including the selection of a working fluid, the determination of the mode, or modes, of heat transfer to be used, and the selection, or development, of any required heat transfer correlations.
Abstract: The thermal aspects are discussed of an immersion-cooled computer designed to operate at cryogenic temperatures. Several of the major thermal design issues are discussed in detail. These include: (1) the selection of a working fluid; (2) the determination of the mode, or modes, of heat transfer to be used: (3) the selection, or development, of any required heat transfer correlations; and (4) the selection of a refrigeration system. The results of a preliminary analysis of a candidate thermal control system are also presented. >
20 citations
References
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Book•
01 Jan 1994
TL;DR: In this paper, the basic models of two-phase flow are discussed and empirical treatments of two phase flow are provided. But the authors focus on convective boiling and condensing.
Abstract: Introduction 1. The basic models 2. Empirical treatments of two-phase flow 3. Introduction to convective boiling 4. Subcooled boiling heat transfer 5. Void fraction and pressure drop in subcooled boiling 6. Saturated boiling heat transfer 7. Critical heat flux in forced convective flow - 1. Vertical uniformly heated tubes 8. Critical heat flux in forced convective flow - 2. More complex situations 9. Condensation 10. Conditions influencing the performance of boiling and condensing systems 11. Multi-component boiling and condensation Appendix Index
2,426 citations
TL;DR: In this article, a regression analysis was applied to the nearly 5000 existing experimental data points for natural convection boiling heat transfer, which can best be represented by subdividing the substances into four groups (water, hydrocarbons, cryogenic fluids and refrigerants) and employing a different set of dimensionless numbers for each group of substances.
710 citations
Book•
01 Jan 1983
TL;DR: In this article, thermal analysis and control of electronic equipment, thermal analysis of electronic devices and their control, thermal control and control in the field of software engineering, is discussed. ǫ
Abstract: Thermal analysis and control of electronic equipment , Thermal analysis and control of electronic equipment , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
339 citations
TL;DR: A survey of the evolution of surface geometries that promote high-performance nucleate boiling can be found in this paper, where the authors survey the development of a high area density of stable nucleation sites whose performance does not deteriorate with time.
Abstract: This paper surveys the evolution of special surface geometries that promote high-performance nucleate boiling. Early work by Jakob and Fritz in 1931 showed that emery paper roughening or machined grooves provided only temporary performance increase. However, this improvement dissipated after a few days to the flat surface value. There was little sustained interest in this unique, but apparently unuseful, phenomenon until the mid-1950s. During the period 1955-1965, supporting fundamental studies of the character and stability of nucleation sites provided a basis for renewed efforts to develop a high area density of stable, artificially formed nucleation sites whose performance does not deteriorate with time. Beginning in 1968 industrial research produced patented technology that achieved the long-sought goal. In 1980 at least six high-performance nucleate boiling surfaces were commercially available. The technology reported in this paper represents a dramatic advance in the field of heat transfer.
192 citations