Visualization of boiling heat transfer on micro porous coated surface in confined space

Chien Yuh Yang, Chien Fu Liu

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

2 Scopus citations

Abstract

Numerous researches have been developed for pool boiling on microporous coated surface in the past decade. The nucleate boiling heat transfer was found to be increased by up to 4.5 times than that on uncoated surface. Recently, the two-phase micro heat exchangers have been considered for high flux electronic devices cooling. The enhancement techniques for improving the nucleate boiling heat transfer performance in the micro heat exchangers have gotten more importance. Previous studies of microporous coatings, however, have been restricted to boiling in unconfined space. No studies have been made on the feasibility of using microporous coatings for enhancing boiling in confined spaces. This study provides an experimental observation of the vapor generation and leaving processes on microporous coatings surface in a 1-mm confined space. It would be helpful for understanding the mechanism of boiling heat transfer and improving the design of two-phase micro heat exchangers. Aluminum particles of average diameter 20 um were mixed with a binder and a carrier to develop a 150 um thickness boiling enhancement paint on a 3.0 cm by 3.0 cm copper heating surface. The heating surface was covered by a thin glass plate with a 1 mm spacer to form a 1 mm vertical narrow space for the test section. The boiling phenomenon was recorded by a high speed camera. In addition to the three boiling regimes observed by Bonjour and Lallemand [1], i.e., isolated deformed bubbles, coalesced bubbles and partial dryout at low, moderate and high heat fluxes respectively in unconfined space, a suction and blowing process was observed at the highest heat flux condition. Owing to the space confinement, liquid was sucked and vapor was expelled periodically during the bubble generation process. This mechanism significantly enhanced the boiling heat transfer performance in confined space.

Original languageEnglish
Title of host publicationASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013
DOIs
StatePublished - 2013
EventASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013 - Sapporo, Japan
Duration: 16 Jun 201319 Jun 2013

Publication series

NameASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013

Conference

ConferenceASME 2013 11th International Conference on Nanochannels, Microchannels and Minichannels, ICNMM 2013
Country/TerritoryJapan
CitySapporo
Period16/06/1319/06/13

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