scispace - formally typeset
Search or ask a question
Journal ArticleDOI

wall Superheat Excursions in the Boiling incipience of Dielectric Fluids

01 Jun 1988-Heat Transfer Engineering (Taylor & Francis Group)-Vol. 9, Iss: 3, pp 19-31
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.
Citations
More filters
Journal ArticleDOI
01 Oct 1989
TL;DR: In this paper, a new type of heat exchange process is described for use in semiconductor heat sinks, which involves the use of subcooled, nucleate boiling at concave curved surfaces where radial acceleration, v/sup 2/r, can be used to develop significant and beneficial buoyancy forces.
Abstract: A new type of heat exchange process is described for use in semiconductor heat sinks. It involves the use of subcooled, nucleate boiling at concave curved surfaces where radial acceleration, v/sup 2//r, can be used to develop significant and beneficial buoyancy forces. The system provides a heat transfer surface with a uniform temperature, i.e. the boiling point of the fluid, and requires no vapor-liquid separation process since all vapor bubbles are immediately condensed in the subcooled liquid, Use of low-boiling-point dielectric fluids, e.g., FC 72 (BP 56 degrees C), establishes a uniform heat sink temperature that is independent of location or environment and does not require elaborate coolant and/or environmental conditioning. The low junction-to-fluid specific thermal resistance, approximately 0.1 degrees C/W-cm/sup 2/, and high heat flux dissipation capability, approximately 6000 W/cm/sup 2/, inherent in this design lend themselves to a system design with high reliability and lower manufacturing costs. Failure rates are reduced and leakage currents are lowered by virtue of lower device operating temperatures resulting from the low-boiling-point coolants. The design lends itself to compact, lightweight construction for high-voltage series operation of devices and permits simplified parallel operation of high-power devices. Experimental studies have demonstrated a heat flux of 6300 W/cm/sup 2/ using FC 77 with a pressure drop of only 2.70 lb/in/sup 2/ over a 1 cm-long heat transfer channel. >

3 citations

Book ChapterDOI
01 Jan 1997
TL;DR: The trend zur Anordnung von mikroelektronischen Bauelementen auf kleinstem Raum stellt zunehmend hohere Anforderungen an das dazugehorige Kuhl system as discussed by the authors.
Abstract: Der Trend zur Anordnung von mikroelektronischen Bauelementen auf kleinstem Raum stellt zunehmend hohere Anforderungen an das dazugehorige Kuhlsystem. Trotz zeitweise auftretender flachenspezifischer Dissipationsleistungen von mehr als 10 W/cm2 durfen die Temperaturen wegen der stets vorhandenen Lotstellen nicht uber 125°C steigen.

3 citations

Journal ArticleDOI
TL;DR: In this paper, a shock tube is used to investigate the bubble dynamics under sudden decrease of ambient pressure, and both the oscillating and monotonously growing bubbles were simultaneously observed.
Abstract: A shock tube is used to investigate the bubble dynamics under sudden decrease of ambient pressure. Both the oscillating and monotonously growing bubbles were simultaneously observed. Theoretical approach is based on the Rayleigh-Plesset and Herring’s equations for incompressible and compressible liquids, respectively. Considering the linear approximation of these equations for the quasiequilibrium state, two critical Weber numbers are defined. They enable one to predict the following modes of the bubble expansion: (i) unbounded growth, (ii) asymptotic growth to limited volume and (iii) attenuated oscillations, depending on the pressure force, viscosity and compressibility of the liquid.

3 citations

Journal ArticleDOI
TL;DR: In this paper, the direct transition from non-boiling to film boiling at critical heat flux (CHF) by exponentially increasing heat input, Q0exp(t/τ), was investigated in a pool of FC-72.
Abstract: The direct transition boiling process from non-boiling to film boiling at critical heat flux (CHF) by exponentially increasing heat input, Q0exp(t/τ), was investigated in a pool of FC-72. Investigations were made on a 1.0 mm diameter gold horizontal cylinder heater under a wide range of system pressures for saturated condition. Direct transition predominantly occurs from heat conduction process in the non-boiling regime by rapid increasing heat input and then followed by incipient boiling and CHF simultaneously. However, during quasi-steady-state heat transfer, it was observed that the direct transition also occurs from single phase natural convection at around atmospheric pressure and by an extent of pre-pressure, which was given to the cylinder surface at atmospheric pressure. Direct transition phenomena were confirmed to exist due to the explosive-like heterogeneous spontaneous nucleation (HSN) in originally flooded cavities on surface. The predictions of direct transition phenomena were also derived from typical incipient boiling superheat and CHF.

3 citations

Journal ArticleDOI
TL;DR: In this paper, the authors focus on heat transfer from a simulated multichip module to a falling dielectric (FC-72) liquid film and show that the vanishingly small contact angle of FC-72 precludes the application of correla- tions currently employed to predict boiling incipience.
Abstract: Controlling boiling incipience is of paramount importance for reliable operation of liquid-cooled microelectronic heat sources during power transients. This study focuses on heat transfer from a simulated multichip module to a falling film. Ex­ periments have been performed to develop an understanding of the influence of sur­ face tension and wetting characteristics on sensible heat transfer and boiling inci­ pience in free-falling dielectric (FC-72) liquid films. The boiling results reveal that the vanishingly small contact angle of FC-72 precludes the application of correla­ tions currently employed to predict incipience. Also, the temperature excursion commonly encountered upon boiling incipience in wetting fluids was nonexistent in all the experimental runs.

3 citations

References
More filters
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

Journal ArticleDOI
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 Jun 1961

571 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

Journal ArticleDOI
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