Heat and mass transfer from a system of closely packed capillaries - Possible choice for wicks

Kumar, Navneet and Arakeri, Jaywant H (2020) Heat and mass transfer from a system of closely packed capillaries - Possible choice for wicks. In: INTERNATIONAL JOURNAL OF THERMAL SCIENCES, 148 .

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Abstract

Evaporation characteristics of a radiatively heated (similar to 1000 W/m(2) of incident heat flux) unconventional porous medium consisting of closely packed vertical capillaries have been investigated. Three stages of mass loss from a conventional porous medium, consisting of spheres, are well known; high evaporation rate in stage 1 is sustained by capillary liquid films, which transport liquid from lower regions of a porous medium to its exposed top surface. We show that in a bundle of capillaries, stage 1 is sustained by near-zero radii (NZR) of contacts, formed throughout the contact line of two or more touching capillaries, which can theoretically lead to infinite height rise. Some of the evaporative features of these NZR of contacts were recently (Kumar and Arakeri, 2018b) explored. With closely packed capillaries, along with the existence of the NZR of contacts (as in rods' case), we get an additional advantage of having inner diameter, which we show act as a reservoir for the nearby NZR of contacts. We report extremely high (time) duration of high rates of evaporation from a bundle of capillaries, which is seemingly impossible to achieve in the conventional systems. In passive systems like loop heat pipes and capillary pumped loops, an additional reservoir is not needed in case a wick consisting of closely packed capillaries are used.

Item Type:	Journal Article
Publication:	INTERNATIONAL JOURNAL OF THERMAL SCIENCES
Publisher:	ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER
Additional Information:	Copyright of this article belongs to ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER
Department/Centre:	Division of Mechanical Sciences > Mechanical Engineering
Date Deposited:	10 Jan 2020 10:28
Last Modified:	10 Jan 2020 10:28
URI:	http://eprints.iisc.ac.in/id/eprint/64078

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