a recent article from chemical engineering, written by daniel bethge, head of research and development at gig karasek gmbh in austria, outlines the equations and simulations that show the changing properties of materials within a wiped film evaporator.
an example of a thin film evaporator. (wikimedia commons)
in a wiped film evaporator, feed material is fed at a constant rate from the top and is distributed as a thin film on the inside through a rotor equipped with wipers. applying heat (via steam) and a vacuum causes the volatile materials to separate.
according to the article, wiped film evaporators are used to recover valuable substances, remove solvents, and concentrate residues. evaporation changes the material from a liquid to a “jelly-like” or powdery material. as the material changes, so does the heat transfer and that is what the article details.
through analytical modeling and computer simulations, the heat transfer rates can be defined and the process easier to understand. this will assist in choosing the correct evaporator technology for the project that is being undertaken.
view the full article at http://www.chemengonline.com/heat-transfer-wiped-film-evaporators.
|