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International Journal of Chemical Engineering
Volume 2017, Article ID 5784627, 9 pages
https://doi.org/10.1155/2017/5784627
Research Article

Modelling the Evaporation Rate in an Impingement Jet Dryer with Multiple Nozzles

1Division of Fluid and Experimental Mechanics, Department of Engineering Science and Mathematics, Luleå University of Technology, 971 87 Luleå, Sweden
2Relitor Engineering AB, Företagsvägen 9, 954 33 Gammelstad, Sweden

Correspondence should be addressed to Anna-Lena Ljung; es.utl@gnujl.anel-anna

Received 22 December 2016; Accepted 5 February 2017; Published 2 March 2017

Academic Editor: Sreepriya Vedantam

Copyright © 2017 Anna-Lena Ljung et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Impinging jets are often used in industry to dry, cool, or heat items. In this work, a two-dimensional Computational Fluid Dynamics model is created to model an impingement jet dryer with a total of 9 pairs of nozzles that dries sheets of metal. Different methods to model the evaporation rate are studied, as well as the influence of recirculating the outlet air. For the studied conditions, the simulations show that the difference in evaporation rate between single- and two-component treatment of moist air is only around 5%, hence indicating that drying can be predicted with a simplified model where vapor is included as a nonreacting scalar. Furthermore, the humidity of the inlet air, as determined from the degree of recirculating outlet air, has a strong effect on the water evaporation rate. Results show that the metal sheet is dry at the exit if 85% of the air is recirculated, while approximately only 60% of the water has evaporated at a recirculation of 92,5%.