Advanced

Entrapment of air during imbibition of agglomerated powder beds

Börjesson, Erik LU ; Karlsson, Jonathan; Innings, Fredrik LU ; Trägårdh, Christian LU ; Bergenståhl, Björn LU and Paulsson, Marie LU (2017) In Journal of Food Engineering 201. p.26-35
Abstract

Complete wetting is crucial for efficient recombination of powders. On the powder bed scale, wetting is governed solely by capillary forces and the resistance to flow, i.e. spontaneous imbibition. Slow or incomplete imbibition of the powder bed may lead to gelling of the liquid front, which will stop the recombination process and cause the formation of lumps, which is usually undesirable. In this study, the spontaneous imbibition of powder beds consisting of spray-dried dairy powders with diverse morphologies has been investigated. Uniform radial spreading of the imbibition front was seen in all the beds, but a large amount of air was trapped in the inter-particle free space in the imbibed volume. A positive correlation was found... (More)

Complete wetting is crucial for efficient recombination of powders. On the powder bed scale, wetting is governed solely by capillary forces and the resistance to flow, i.e. spontaneous imbibition. Slow or incomplete imbibition of the powder bed may lead to gelling of the liquid front, which will stop the recombination process and cause the formation of lumps, which is usually undesirable. In this study, the spontaneous imbibition of powder beds consisting of spray-dried dairy powders with diverse morphologies has been investigated. Uniform radial spreading of the imbibition front was seen in all the beds, but a large amount of air was trapped in the inter-particle free space in the imbibed volume. A positive correlation was found between bed porosity and the fraction of air trapped in the bed after imbibition. Since the amount of trapped air was calculated as a fraction of the porosity of the dry bed, this relation was unexpected. The large fraction of air trapped in the bed and the uniform radial spreading of the imbibition front indicate considerable heterogeneity of bed on the microscopic scale, but a homogenous structure on the macroscopic scale. Possible explanations of the large fraction of trapped air are the presence of local dead-end structures in the bed and film flow of the imbibing liquid.

(Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Imbibition, Porosity, Porous media, Powder bed, Spontaneous imbibition, Trapping of air
in
Journal of Food Engineering
volume
201
pages
10 pages
publisher
Elsevier
external identifiers
  • scopus:85009975895
  • wos:000394635800004
ISSN
0260-8774
DOI
10.1016/j.jfoodeng.2017.01.004
language
English
LU publication?
yes
id
bd10f2f5-67ed-4f37-a580-312b18c86da4
date added to LUP
2017-02-03 07:12:20
date last changed
2018-01-07 11:47:46
@article{bd10f2f5-67ed-4f37-a580-312b18c86da4,
  abstract     = {<p>Complete wetting is crucial for efficient recombination of powders. On the powder bed scale, wetting is governed solely by capillary forces and the resistance to flow, i.e. spontaneous imbibition. Slow or incomplete imbibition of the powder bed may lead to gelling of the liquid front, which will stop the recombination process and cause the formation of lumps, which is usually undesirable. In this study, the spontaneous imbibition of powder beds consisting of spray-dried dairy powders with diverse morphologies has been investigated. Uniform radial spreading of the imbibition front was seen in all the beds, but a large amount of air was trapped in the inter-particle free space in the imbibed volume. A positive correlation was found between bed porosity and the fraction of air trapped in the bed after imbibition. Since the amount of trapped air was calculated as a fraction of the porosity of the dry bed, this relation was unexpected. The large fraction of air trapped in the bed and the uniform radial spreading of the imbibition front indicate considerable heterogeneity of bed on the microscopic scale, but a homogenous structure on the macroscopic scale. Possible explanations of the large fraction of trapped air are the presence of local dead-end structures in the bed and film flow of the imbibing liquid.</p>},
  author       = {Börjesson, Erik and Karlsson, Jonathan and Innings, Fredrik and Trägårdh, Christian and Bergenståhl, Björn and Paulsson, Marie},
  issn         = {0260-8774},
  keyword      = {Imbibition,Porosity,Porous media,Powder bed,Spontaneous imbibition,Trapping of air},
  language     = {eng},
  month        = {05},
  pages        = {26--35},
  publisher    = {Elsevier},
  series       = {Journal of Food Engineering},
  title        = {Entrapment of air during imbibition of agglomerated powder beds},
  url          = {http://dx.doi.org/10.1016/j.jfoodeng.2017.01.004},
  volume       = {201},
  year         = {2017},
}