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Investigation of wall temperature and heat flux distribution during nucleate boiling in the presence of an electric field

Schweizer, N. and Di Marco, P. and Stephan, Peter (2011):
Investigation of wall temperature and heat flux distribution during nucleate boiling in the presence of an electric field.
In: Proceedings 6th International Conference on Two-Phase Systems for Ground and Space Applications, [Conference or Workshop Item]

Abstract

Heating wall temperature distribution and bubble shapes were measured during nucleate boiling of FC-72 in microgravity in the presence of an electric field. The presented results are part of the results obtained during the 50th ESA parabolic flight campaign and focused on the electric field experiments. A 25 \textgreekmm stainless steel foil served as heated wall for the boiling process. The temperature distribution of the foil was measured via infrared thermography at a frame rate of 1000 Hz and with a resolution of 30 \textgreekmm/pixel. The bubbles were observed by a synchronized high speed camera. A washer shaped electrode was located parallel to the heated wall. The electrode was charged to up to +10 kV while the heating foil served as ground potential. The effect of the electric field created by this configuration on the boiling process was investigated for different boiling states. Due to the absence of buoyancy in microgravity the bubbles generally do not detach from the heating foil with the given heat fluxes. The electric force on the bubbles generated by the field gradient sucked the vapor through the center hole of the electrode. Thereby, a reliable bubble detachment and re-wetting mechanism could be established and allowed the implementation of a nucleate boiling process in microgravity.

Item Type: Conference or Workshop Item
Erschienen: 2011
Creators: Schweizer, N. and Di Marco, P. and Stephan, Peter
Title: Investigation of wall temperature and heat flux distribution during nucleate boiling in the presence of an electric field
Language: German
Abstract:

Heating wall temperature distribution and bubble shapes were measured during nucleate boiling of FC-72 in microgravity in the presence of an electric field. The presented results are part of the results obtained during the 50th ESA parabolic flight campaign and focused on the electric field experiments. A 25 \textgreekmm stainless steel foil served as heated wall for the boiling process. The temperature distribution of the foil was measured via infrared thermography at a frame rate of 1000 Hz and with a resolution of 30 \textgreekmm/pixel. The bubbles were observed by a synchronized high speed camera. A washer shaped electrode was located parallel to the heated wall. The electrode was charged to up to +10 kV while the heating foil served as ground potential. The effect of the electric field created by this configuration on the boiling process was investigated for different boiling states. Due to the absence of buoyancy in microgravity the bubbles generally do not detach from the heating foil with the given heat fluxes. The electric force on the bubbles generated by the field gradient sucked the vapor through the center hole of the electrode. Thereby, a reliable bubble detachment and re-wetting mechanism could be established and allowed the implementation of a nucleate boiling process in microgravity.

Divisions: 16 Department of Mechanical Engineering > Institute for Technical Thermodynamics (TTD)
Exzellenzinitiative > Clusters of Excellence > Center of Smart Interfaces (CSI)
16 Department of Mechanical Engineering
Zentrale Einrichtungen
Exzellenzinitiative
Exzellenzinitiative > Clusters of Excellence
Event Title: Proceedings 6th International Conference on Two-Phase Systems for Ground and Space Applications
Date Deposited: 17 Mar 2015 14:59
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