Falling film hydrodynamics of black liquor under evaporative conditions
Artikel i vetenskaplig tidskrift, 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.


Falling film

High Pr number


Heat transfer

Black liquor


Miriam Johansson

Industriella energisystem och -tekniker

I. Leifer

University of California

Lennart Vamling

Industriella energisystem och -tekniker

Lars Olausson

Metso Power AB

International Journal of Heat and Mass Transfer

0017-9310 (ISSN)

Vol. 2009 2769-2778



Övrig annan teknik

Kemiska processer