Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015.
Falling film evaporation is used in various fields, e.g.
food and pulp & paper industry. Evaporation is very energy
intense and relatively small efficiency improvements to the
techniques can lead to large savings in absolute numbers.
Falling film evaporation is affected by the wave dynamics;
hence further knowledge of the behaviour of the liquid film
flow can promote efficiency improvements.
In this work, two new measurement approaches have
been investigated. The first approach is to use a laser
triangulation scanner combined with a high-speed camera
where the laser scanner continuously measures the film
thickness along a vertical line, resolving the flow pattern in
high detail. The second approach is to measure local wall
temperatures, enabling calculation of local heat transfer
coefficients at any desired location.
These methods has been tested and evaluated in a falling
film test facility. Both approaches have proven to give
valuable insights into the process and the results are in good
agreement with literature data.