Boiling enhancement coating

Details Boiling enhancement coating Boiling enhancement coating

1996-12-02

1998-09-29

Zirker, Daniel

Stock material or miscellaneous articles

Structurally defined web or sheet

Discontinuous or differential coating, impregnation or bond

427386, 428413, 523440, B32B 1508, C08K 300

Patent

active

058143920

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to the fields of immersion cooling and boiling heat transfer from a surface to a liquid. More particularly the invention relates to surface enhancements which increase the critical heat flux and reduce wall superheating by increasing boiling nucleation sites on the surface. The surface enhancements are accomplished by applying to the surface a composition comprising particulate elements, glue and a solvent, and then curing the applied material by evaporating the solvent.
2. Description of the Related Art
Boiling heat transfer is a method of dissipating high amounts of thermal energy. When evaluating the nucleate boiling heat transfer performance of a surface, three parameters should be considered. The first parameter is the wall superheat required to initiate boiling. The surface must reach the incipient wall superheat condition to initiate the nucleation process. The incipient wall superheat is inversely proportional to the volume of vapor/gas entrapped in a surface irregularity. The second performance parameter to be considered is the heat transfer coefficient in the nucleate boiling regime. Increasing the boiling heat transfer coefficient from the surface leads to lower surface temperatures. More heat is removed as the nucleation site density of the surface increases. The third boiling performance parameter to be considered is the Critical Heat Flux (CHF) which is the highest heat flux that can be removed without exposing the surface to film boiling.
Nomenclature
The following nomenclature is used throughout the application:


______________________________________ A.sub.h Projected Heater Surface Area (0.84 cm.sup.2) A.sub.j Total Vapor Jet Cross-Sectional Area A.sub.w Heater Surface Area Feeding a Single Vapor Jet CHF Critical Heat Flux g Gravitational Acceleration h Heat Transfer Coefficient h.sub.fg Heat of Vaporization .kappa. Thermal Conductivity L Length R Resistance or Thermal Resistance R.sub.tcond Total Conductive Thermal Resistance T.sub.bulk Test Liquid Temperature T.sub.ref Reference Surface (Aluminum Foil) Temperature T.sub.tc Thermocouple Temperature T.sub.w Paint or Heater Surface Ternperature .DELTA.T Wall Superheat (T.sub.ref - T.sub.bulk) q Heat Flux (W/cm.sup.2) q.sub.maxz Zuber Critical Heat Flux .rho..sub.f Liquid Density .rho..sub.g Vapor Density .sigma. Surface Tension .lambda..sub.T Taylor 1-D Wavelength P.sub.sat Saturation Pressure r.sub.b Embryonic Bubble Radius T.sub.crit Critical Ternperature ______________________________________
The mechanism which causes the CHF continues to be the focus of many investigations. Several theories exist which attempt to describe this mechanism. The most widely accepted theory was developed by Zuber (1959) for pool boiling on an infinite, upward facing, horizontal flat plate. Zuber's theory emphasizes the collapse of vapor escape routes from the heated surface due to hydrodynamic instabilities and leads to the following correlation: -.rho..sub.g)!.sup.1/4 ( 1)
Studies focusing on boiling incipience and nucleation site distributions using non-highly wetting liquids (water, ether, methanol), Griffith and Wallis (1959), Hsu (1962), and Chowdhury and Winterton (1985), verify that surface roughness significantly affects incipient superheat and nucleate boiling heat transfer. Many studies have been conducted concerning boiling incipience using highly wetting dielectric liquids. A summary of these investigations conducted prior to 1986 can be found in Bar-Cohen and Simon (1988). In general, wide variations in incipience superheats were reported and theories for this phenomenon were presented. Bar-Cohen and Simon concluded commonly accepted incipience theories for non-highly wetting liquids can not be applied to highly wetting dielectric liquids. You et al. (1990a) observed wide variations (.about.20.degree. C.) in incipience superheats in highly wetting dielectric liquids and noted incipien

REFERENCES:
patent: 3301314 (1967-01-01), Gaertner
patent: 3412043 (1968-11-01), Gilliland
patent: 3686139 (1972-08-01), Lubin
patent: 3706127 (1972-12-01), Oktay et al.
patent: 4050507 (1977-09-01), Chu et al.
patent: 4479890 (1984-10-01), Prabhu et al.
patent: 4537632 (1985-08-01), Mosser
patent: 4544623 (1985-10-01), Audykowski et al.
patent: 4786437 (1988-11-01), Ehrreich
patent: 5051208 (1991-09-01), Bowns et al.
patent: 5095052 (1992-03-01), Delano et al.
Anderson and Mudawar, "Microelectronic Cooling by Enhanced Pool Boiling of a Dielectric Fluorocarbon Liquid," Journal of Heat Transfer, 111:752-759, 1989.
Chowdhury and Winterton, "Surface Effects in Pool Boiling," Int. J. Heat. Mass Transfer, 28(10):1881-1889, 1985.
Frieser and Reeber, "Surface Treatments of Silicon to Enhance Thermal Nucleation," Journal of Applied Electrochemistry, 10:449-457, 1980.
Marto and Leper, "Pool Boiling Heat Transfer from Enhanced Surfaces to Dielectric Fluids," Journal of Heat Transfer, 104:292-299, 1982.
Thome, J.R., 1990, "Enhanced Boiling Heat Transfer," Hemisphere Publishing Corp., New York, NY; pp. 28-63, 78-90.
You et al., "Experimental Investigation of Nucleate Boiling Incipience with a Highly-wetting Dielectric Fluid (R-113)," Int. J. Heat Mass Transfer, 33(1):105-117, 1990.
You et al., "A Technique for Enhancing Boiling Heat Transfer with Application to Cooling of Electronic Equipment," IEEE Transactions on Components, Hybrids, and Manufacturing Technology, 15(5):823-831, 1992.
Dialog Search dated Feb. 22, 1994.
"High Temperature and High Thermally Conductive Epoxies", 3 pages from OMEGA International Search Report, Jul. 26, 1995.
Orr, Kirk-Othmer Ency. of Chem. Tech., 3rd ed., John Wiley & Sons, New York, vol. 21, pp. 10-131.

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