NASA Logo, External Link
Facebook icon, External Link to NASA STI page on Facebook Twitter icon, External Link to NASA STI on Twitter YouTube icon, External Link to NASA STI Channel on YouTube RSS icon, External Link to New NASA STI RSS Feed AddThis share icon
 

Record Details

Record 31 of 234
Enhanced Boiling on Micro-Configured Composite Surfaces Under Microgravity Conditions
Offline Availability: Go to Request Form
Abstract: Two experimental setups: High Heat Flux Pool Boiling Setup and Optical system of Measuring Contact Angle and Spreading Parameters were established and a series of experiments was conducted. The experimental work on the nucleate boiling performance of both Freon-113 and water on the composite surfaces has been finished and the results show that the composite surface with 25% volume fraction of graphite fibers in the copper matrix has the best enhancing performance. Stronger enhancement was obtained for water compared to Freon-113. The wall superheat initiating boiling was reduced 40% and 35% and the heat flux of the nucleate boiling was augmented up to ten times and 6.7 times, respectively. A bubble departure model has been presented to explain the enhancement mechanism of the boiling heat transfer on the composite surfaces. A powerful optical method to measure contact angle and spreading parameters of liquids on solid surfaces, including both transparent and non-transparent substrates, has been developed and successfully used in the measurements for various liquid-solid systems. The experimental work on identification of profiles near three-phase line by laser shadowgraphy method has been finished and the characteristics of the three-phase line for different liquid-solid systems were unveiled, which is very important to understand the mechanism of boiling under microgravity conditions. The four basic patterns of sessile profile were discovered through caustics and caustic-diffraction analysis by applying wave theory in shadowgraphy technology, which contributes to clearly explain the different characteristics of wetting and spreading of various liquids on a solid surface, and therefore to further understand the bubble departure mechanisms. A new working pattern of heat pipes using working fluids with positive surface-tension gradient against temperature was discovered and analyzed, and then the new heat pipe systems using this kind of working fluids have been presented. Two patent devices, i.e. Shadowgraphic Method to Measure Properties of Sessile Drops and Heat Pipe Systems Using New Working Fluids, have been developed; the former has been approved by The United States Patent & Trademark Office and the latter is being examined.
Publication Date: Jan 01, 2004
Document ID:
20040034008
(Acquired Mar 18, 2004)
Subject Category: FLUID MECHANICS AND THERMODYNAMICS
Coverage: Final Report
Document Type: Technical Report
Contract/Grant/Task Num: NCC3-1060
Financial Sponsor: NASA Glenn Research Center; Cleveland, OH, United States
Organization Source: NASA Glenn Research Center; Cleveland, OH, United States
Description: 4p; In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: No Copyright
NASA Terms: NUCLEATE BOILING; FREON; HEAT FLUX; HEAT PIPES; HEAT TRANSFER; BUBBLES; BOILING; WORKING FLUIDS; SHADOWGRAPH PHOTOGRAPHY; SOLID SURFACES; INTERFACIAL TENSION; DROPS (LIQUIDS); DIFFRACTION; MICROGRAVITY; SUBSTRATES
› Back to Top
Find Similar Records
NASA Logo, External Link
NASA Official: Gerald Steeman
Site Curator: STI Program
Last Modified: September 08, 2011
Contact Us