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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TL;DR: In this paper, the effects of non-condensable gases and surface aging on boiling curves were considered, and the physical mechanism of boiling hysteresis was discussed in terms of irregular activation of vapor embryos within larger cavities.
37 citations
23 May 1990
TL;DR: In this article, an experimental study of pool boiling was conducted using cylindrical heater surfaces of platinum, silicon, silicon dioxide, and aluminum oxide, which were immersed in FC-72 and R-113, saturated at 1-a.m. pressure.
Abstract: An experimental study of pool boiling was conducted using cylindrical heater surfaces of platinum, silicon, silicon dioxide, and aluminum oxide. They were immersed in FC-72 and R-113, saturated at 1-a.t.m. pressure. The effects of fluid and surface material on boiling incipience and on the nucleate boiling curve was investigated. A probabilistic representation was used to present the incipience wall superheat values, which scattered widely for ostensibly identical runs. The difference in incipience wall superheat values between those with FC-72 and R-113 was significant, but the surface material effect on boiling incipience was small. The surface material effect was more pronounced in the nucleate boiling regime than on the incipience process. >
35 citations
TL;DR: In this paper, the authors investigated heat transfer from an in-line 1 x 10 array of discrete heat sources, flush mounted to protruding substrates located on the bottom wall of a horizontal flow channel.
Abstract: Experiments have been performed using water and FC-77 to investigate heat transfer from an in-line 1 x 10 array of discrete heat sources, flush mounted to protruding substrates located on the bottom wall of a horizontal flow channel. The data encompass flow regimes ranging from mixed convection to laminar and turbulent forced convection. Buoyancy-induced secondary flows enhanced heat transfer at downstream heater locations and provided heat transfer coefficients comparable to upstream values. Upstream heating extended enhancement on the downstream heaters to larger Reynolds numbers. Higher Prandtl number fluids also extended heat transfer enhancement to larger Reynolds numbers, while a reduction in channel height suppressed buoyancy driven flows, thereby reducing enhancement. The protrusions enhanced the transition to turbulent forced convection, causing the critical Reynolds number to decrease with increasing row number. The transition region was characterized by large heater-to-heater variations in the average Nusselt number.
35 citations
TL;DR: In this paper, a modified version of Sun and Lienhard's hydrodynamic critical heat flux (CHF) correlation for cylindrical geometries was developed in 1970.
24 citations
01 Jan 2006
TL;DR: In this paper, a discussion of the thermophysics of phase-change processes and a description of the available dielectric liquid cooling techniques and their history is provided, as well as available correlations for predicting the heat transfer coefficients and limiting heat transfer rates.
Abstract: The inexorable rise in chip power dissipation and emergence of on-chip hot spots with heat fluxes approaching 1k W/cm 2 has turned renewed attention to direct cooling with dielectric liquids. Use of dielectric liquids in intimate contact with the heat dissipating surfaces eliminates the deleterious effects of solid-solid interface resistances and harnesses the highly efficient phase-change processes to the critical thermal management of advanced IC chips. In the interest of defining the state-of-the-art in direct liquid cooling, this paper begins with a discussion of the thermophysics of phase-change processes and a description of the available dielectric liquid cooling techniques and their history. It then describes the phenomenology of pool boiling, spray/jet impingement, gas- assisted evaporation, and synthetic jet impingement with dielectric liquids. Available correlations for predicting the heat transfer coefficients and limiting heat transfer rates, as well as documented empirical results for these promising techniques for on-chip hot spot cooling, are also provided and compared. Hydraulic diameter (m) E Electric field (V/m) g Gravitational acceleration ðm/s 2 Þ G Mass flux ðkg/m 2 � sÞ h Local heat transfer coefficient ðW/m 2 � kÞ h Average heat transfer coefficient ðW/m 2 � kÞ hfg Latent heat of vaporization (J/kg) k Thermal conductivity (W/m-K)
24 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