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Flow Patterns and Heat Transfer in Thin Liquid Films on Walls With Straight, Meandering and Zigzag Mini-Grooves

Löffler, K. and Yu, H. and Gambaryan-Roisman, Tatiana and Stephan, Peter (2008):
Flow Patterns and Heat Transfer in Thin Liquid Films on Walls With Straight, Meandering and Zigzag Mini-Grooves.
In: ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels, [Online-Edition: http://dx.doi.org/10.1115/ICNMM2008-62318],
[Conference or Workshop Item]

Abstract

Thin liquid films flowing along solid walls are widely used in technological applications in which high rates of heat and mass transport are required. The transport processes can be further intensified by using structured walls. In the present work hydrodynamics and heat transfer in falling liquid films on heated vertical and inclined walls with mini-grooves are studied experimentally and theoretically/numerically. The experiments are performed with straight, meandering and zigzag mini-grooves. The film dynamics is investigated using a confocal chromatic sensoring (CHR) technique. The flow patterns and the temperature of the liquid-gas interface are visualized using the high-speed infrared thermography. The wall temperature distribution is measured with thermocouples. A numerical model for description of the velocity and temperature fields in the thermal entrance region of the falling films on smooth and structured walls is developed. This model is based on the solution of the Graetz-Nusselt problem for falling films on grooved plates. We show that the mini-grooves significantly affect the flow patterns, film stability and heat transfer in falling liquid films. Using grooved walls leads to the increase of the maximal attainable heat transfer rate.

Item Type: Conference or Workshop Item
Erschienen: 2008
Creators: Löffler, K. and Yu, H. and Gambaryan-Roisman, Tatiana and Stephan, Peter
Title: Flow Patterns and Heat Transfer in Thin Liquid Films on Walls With Straight, Meandering and Zigzag Mini-Grooves
Language: German
Abstract:

Thin liquid films flowing along solid walls are widely used in technological applications in which high rates of heat and mass transport are required. The transport processes can be further intensified by using structured walls. In the present work hydrodynamics and heat transfer in falling liquid films on heated vertical and inclined walls with mini-grooves are studied experimentally and theoretically/numerically. The experiments are performed with straight, meandering and zigzag mini-grooves. The film dynamics is investigated using a confocal chromatic sensoring (CHR) technique. The flow patterns and the temperature of the liquid-gas interface are visualized using the high-speed infrared thermography. The wall temperature distribution is measured with thermocouples. A numerical model for description of the velocity and temperature fields in the thermal entrance region of the falling films on smooth and structured walls is developed. This model is based on the solution of the Graetz-Nusselt problem for falling films on grooved plates. We show that the mini-grooves significantly affect the flow patterns, film stability and heat transfer in falling liquid films. Using grooved walls leads to the increase of the maximal attainable heat transfer rate.

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: ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels
Date Deposited: 17 Mar 2015 15:14
Official URL: http://dx.doi.org/10.1115/ICNMM2008-62318
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