Evaporation of single component viscous liquids in a metal falling film evaporator |
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Authors: | Stefanie Arndt Stephan Scholl |
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Institution: | 1.Institut für Chemische und Thermische Verfahrenstechnik,Technische Universit?t Braunschweig,Braunschweig,Germany |
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Abstract: | Heat transfer for single component falling film evaporation has been investigated in a stainless steel single tube falling
film evaporator. The tube had a heated length of 2,500 mm. Propylene glycol and cyclohexanol have been used as evaporating
media. Liquid film running down the tube, is formed on the inner side of the tube. For the distribution of liquid two different
devices were examined. Process equipment was operated in pump-around mode with the distillate being condensed and recycled.
Results show that none of the available correlations for heat transfer in falling film evaporation is able to describe the
results qualitatively as well as quantitatively. Using different film distribution devices, a significant influence of the
Reynolds number for the transition from laminar to turbulent flow is seen. However, differences between experimental results
and correlations in literature cannot be explained only by usage of different film distributions, in particular when the correlation
is based on measurements with a different tube length. A model approach is presented for cyclohexanol as evaporating medium
with a flat weir as film distributor. |
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Keywords: | |
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