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Experimental study of local temperature distribution and heat transfer mechanisms during nucleate boiling of binary mixtures

Wagner, E. and Stephan, Peter (2008):
Experimental study of local temperature distribution and heat transfer mechanisms during nucleate boiling of binary mixtures.
Proceedings 5th European Thermal Sciences Conference, [Conference or Workshop Item]

Abstract

An experimental study of nucleate boiling heat transfer with the fluids FC-84, FC-3284 and a 0.5 molar mixture has been carefully carried out. Therefore, a test section was built where nucleate boiling is performed ontop of a 20 µm thick stainless steel heating foil. At first the global heat transfer coefficients (HTCs) were analysed using an infrared (IR) sensor for measuring the average temperature at the rear site of the heating foil. Experiments were performed at 500 and 950 mbar with the pure fluids and the 0.5 molar mixture. It was found out that the more volatile fluid FC-3284 showed the highest HTCs. FC-84 showed medium and the 0.5 molar binary mixture the lowest HTCs. Furthermore, local measurements were arranged, with isolated vapor bubbles generated at only one active nucleation site. For analyzing the heater temperature distribution, a high-speed IR camera was used, capturing the rear site of the heating foil. From this temperature information the local heat flux between the heater and the fluid was computed, applying the energy balance to every pixel of the IR images. The local heat flux at the contact line between the vapour/liquid interface and the wall was analysed during the growth and departure of single bubbles. The local heat fluxes appeared in the same relation like during the global measurements: FC-3284 showed the highest heat fluxes, FC-84 medium heat fluxes, and the lowest were observed with the binary mixture.

Item Type: Conference or Workshop Item
Erschienen: 2008
Creators: Wagner, E. and Stephan, Peter
Title: Experimental study of local temperature distribution and heat transfer mechanisms during nucleate boiling of binary mixtures
Language: German
Abstract:

An experimental study of nucleate boiling heat transfer with the fluids FC-84, FC-3284 and a 0.5 molar mixture has been carefully carried out. Therefore, a test section was built where nucleate boiling is performed ontop of a 20 µm thick stainless steel heating foil. At first the global heat transfer coefficients (HTCs) were analysed using an infrared (IR) sensor for measuring the average temperature at the rear site of the heating foil. Experiments were performed at 500 and 950 mbar with the pure fluids and the 0.5 molar mixture. It was found out that the more volatile fluid FC-3284 showed the highest HTCs. FC-84 showed medium and the 0.5 molar binary mixture the lowest HTCs. Furthermore, local measurements were arranged, with isolated vapor bubbles generated at only one active nucleation site. For analyzing the heater temperature distribution, a high-speed IR camera was used, capturing the rear site of the heating foil. From this temperature information the local heat flux between the heater and the fluid was computed, applying the energy balance to every pixel of the IR images. The local heat flux at the contact line between the vapour/liquid interface and the wall was analysed during the growth and departure of single bubbles. The local heat fluxes appeared in the same relation like during the global measurements: FC-3284 showed the highest heat fluxes, FC-84 medium heat fluxes, and the lowest were observed with the binary mixture.

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 5th European Thermal Sciences Conference
Date Deposited: 17 Mar 2015 15:01
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