Falling film hydrodynamics of black liquor under evaporative conditions
Journal article, 2009

Bubbles were observed in a thin, evaporating, falling film of black liquor (a fluid mixture generated during the pulp production) on the exterior wall of a research evaporator. Because the presence of bubbles could not be explained by nucleate boiling, a combination of turbulent vapour entrainment and effects due to surface-active compounds – surfactants – is proposed. Black liquor contains numerous surfactants, which are likely to enhance bubble formation and stabilization in the fluid and on the film interface. One observed important effect of bubble formation was fluid loss due to bubble-bursting aerosolization (sputtering). Also, bubbles and bubble processes probably alter the film velocity-profile and heat transfer resistance, thereby affecting heat transfer across the film and hence evaporator efficiency.

Heat transfer


High Pr number


Black liquor

Falling film


Miriam Johansson

Industrial Energy Systems and Technologies

I. Leifer

University of California

Lennart Vamling

Industrial Energy Systems and Technologies

Lars Olausson

Metso power AB

International Journal of Heat and Mass Transfer

0017-9310 (ISSN)

Vol. 2009 52 2769-2778

Subject Categories

Energy Engineering

Other Engineering and Technologies not elsewhere specified

Chemical Process Engineering

Chemical Engineering



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