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ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

BOILING AND CAPILLARY LIMIT ENHANCEMENT OF A HEAT PIPE WICK USING BIPOROUS CAPILLARY STRUCTURE

Get access (open in a dialog) DOI: 10.1615/IHTC13.p5.180
12 pages

Abstract

A biporous medium is a porous medium that has two level characteristic capillary pore radii. In present work, the biporous medium is made with sintering together clusters of spherical copper powder into a layer of uniform thickness and used as an evaporating surface. During the operation of the biporous wick, clusters are in a capillary contact and pump working fluid to evaporating menisci located on the surface of the clusters, while pores between clusters act as vapor channels to remove the vapor from the wick. The biporous wicks are very attractive candidates for high heat flux applications. For an optimal operation of a biporous wick geometrical parameters of the wick, such as powder size, cluster size, wick thickness, and liquid feed length need to be optimized in terms of capillarity and liquid permeability of small pores between the powder, vapor permeability of large pores between the clusters, and effective thermal conductivity of the wick, in a way to remove maximum heat flux at a minimum superheat. In this work, thirteen biporous wicks with cluster average diameters 302, 605, 855, and 1015 μm and powder particle average diameters 38, 58, and 76 μm and one wick made of porous particles with inner pore size unknown were sintered into wicks of uniform thickness. Wicks were tested with degassed distilled water at 0.07 bar vapor pressure. The best performed biporous wick with cluster/powder/thickness [μm] 605/38/2000 removing 332.1 W/cm2 at effective heat transfer coefficient 5.3 W/cm2K and interface wick/wall temperature 104.5 °C.