TU Darmstadt / ULB / TUbiblio

Heat Transfer Enhancement in Forced Convective Boiling in Microchannels by Periodic Electrospun Nanofiber Coatings.

Yarin, A. L. and Freystein, M. and Kolberg, S. and Sinha-Ray, S. and Sahu, R. and Spiegel, L. and Gambaryan-Roisman, Tatiana and Stephan, Peter (2015):
Heat Transfer Enhancement in Forced Convective Boiling in Microchannels by Periodic Electrospun Nanofiber Coatings.
In: APS March Meeting Abstracts, San Antonio, Texas, March 2–6, 2015, In: Bulletin of the American Physical Society, [Conference or Workshop Item]

Abstract

To enhance heat transfer in forced convective boiling the microchannel bottom was amended by a nano-texture - periodic rectangular mats of electrospun polymer nanofibers. The fibers were ~ 300-500 nm in diameter and the mat thicknesses were about 6-15 μm. The test fluid was FC-72 and the flow in microchannels contained trains of Taylor bubbles. The role of the nanofibers was to retain the warm microchannel bottom wet, to prevent dry-out and thus to enhance the heat removal rate. In the present experiments the time-average heat flux and heat transfer coefficient at the nanofiber-coated domains were found to be 1.5-2 times higher than those at the uncoated ones. Accordingly, a significant decrease (by 5-8 K) in the superheat was observed at the same Re of 387 and power supply of 36.1 kW/m2. At a higher Re of 432 and lower power supply of 28.1 kW/m2 similar trends in the heat removal rate and surface superheat were found. The significant enhancement of the heat transfer results from the fact that nanofiber mats facilitate wetting of surface under passing Taylor bubbles, thus delaying formation of vapor flow at the channel bottom. The interstices of the nanofiber mat act as the nucleation sites facilitating formation of tiny bubbles, which eventually results in a higher heat removal rate from the surface at a reduced superheat.

Item Type: Conference or Workshop Item
Erschienen: 2015
Creators: Yarin, A. L. and Freystein, M. and Kolberg, S. and Sinha-Ray, S. and Sahu, R. and Spiegel, L. and Gambaryan-Roisman, Tatiana and Stephan, Peter
Title: Heat Transfer Enhancement in Forced Convective Boiling in Microchannels by Periodic Electrospun Nanofiber Coatings.
Language: English
Abstract:

To enhance heat transfer in forced convective boiling the microchannel bottom was amended by a nano-texture - periodic rectangular mats of electrospun polymer nanofibers. The fibers were ~ 300-500 nm in diameter and the mat thicknesses were about 6-15 μm. The test fluid was FC-72 and the flow in microchannels contained trains of Taylor bubbles. The role of the nanofibers was to retain the warm microchannel bottom wet, to prevent dry-out and thus to enhance the heat removal rate. In the present experiments the time-average heat flux and heat transfer coefficient at the nanofiber-coated domains were found to be 1.5-2 times higher than those at the uncoated ones. Accordingly, a significant decrease (by 5-8 K) in the superheat was observed at the same Re of 387 and power supply of 36.1 kW/m2. At a higher Re of 432 and lower power supply of 28.1 kW/m2 similar trends in the heat removal rate and surface superheat were found. The significant enhancement of the heat transfer results from the fact that nanofiber mats facilitate wetting of surface under passing Taylor bubbles, thus delaying formation of vapor flow at the channel bottom. The interstices of the nanofiber mat act as the nucleation sites facilitating formation of tiny bubbles, which eventually results in a higher heat removal rate from the surface at a reduced superheat.

Title of Book: APS March Meeting Abstracts
Series Name: Bulletin of the American Physical Society
Volume: 60
Divisions: 16 Department of Mechanical Engineering
16 Department of Mechanical Engineering > Institute for Technical Thermodynamics (TTD)
Exzellenzinitiative
Exzellenzinitiative > Clusters of Excellence
Event Location: San Antonio, Texas
Event Dates: March 2–6, 2015
Date Deposited: 20 Feb 2017 17:42
Related URLs:
Export:

Optionen (nur für Redakteure)

View Item View Item