Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Simulation of a Vibrated Fluidised Bed Dryer for Solids containing a Multicomponent Moisture
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. (Drying)
KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Transport Phenomena. (Drying)
2006 (English)In: XXII Interamerican Congress of Chemical Engineering, CIIQ 2006 and V Argentinian Congress of Chemical Engineering, CAIQ 2006 - Innovation and Management for Sustainable Development 2006 22nd Interamerican Congress of Chemical Engineering, CIIQ 2006 and 5th Argentinian Congress of Chemical Engineering, CAIQ 2006, Buenos Aires, Argentina, 1 October 2006 through 4 October 2006 / [ed] Oscar Pagola, Buenos Aires, Argentina: Argentine Association of Chemical Engineers (AAIQ) , 2006, 01d-301 p.Conference paper, Published paper (Refereed)
Abstract [en]

The drying of solids in a continuously worked vibrated fluidised bed dryer is studied by simulations. A model considering the drying of a thin layer of particles wetted with a multicomponent mixture is developed. Particles are assumed well mixed in the direction of the airflow and only the longitudinal changes of liquid content, liquid composition and particle temperature are considered. Interactive diffusion and heat conduction are considered the main mechanisms for mass and heat transfer within the particles. Assuming a constant matrix of effective multicomponent diffusion coefficients and thermal conductivity of the wet particles analytical solutions of the diffusion and conduction equations are obtained. The variation of both the diffusion coefficients and the effective thermal conductivity of the particles along the dryer is taken into account by a stepwise application of the analytical solution in space intervals with averaged coefficients from previous locations in the dryer. The analytical solution gives a good insight into the selectivity of the drying process and can be used to estimate aroma retention during drying. The solution is computationally fast; therefore, the experimental verification of this approximate model would introduce an important computational economy since the rigorous treatment of multicomponent drying involves tedious and time-consuming calculations.

Place, publisher, year, edition, pages
Buenos Aires, Argentina: Argentine Association of Chemical Engineers (AAIQ) , 2006. 01d-301 p.
Keyword [en]
Aroma retention, Drying selectivity, Multicomponent drying
National Category
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-28898Scopus ID: 2-s2.0-84992385055OAI: oai:DiVA.org:kth-28898DiVA: diva2:390502
Conference
22nd Inter-American Congress of Chemical Engineering. Buenos Aires, Argentina. October 1-4, 2006.
Note

QC 20110124

Available from: 2011-01-21 Created: 2011-01-21 Last updated: 2017-02-23Bibliographically approved
In thesis
1. An Analytical Solution Applied to Heat and Mass Transfer in a Vibrated Fluidised Bed Dryer
Open this publication in new window or tab >>An Analytical Solution Applied to Heat and Mass Transfer in a Vibrated Fluidised Bed Dryer
2011 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

A mathematical model for the drying of particulate solids in a continuous vibrated fluidised bed dryer was developed and applied to the drying of grain wetted with a single liquid and porous particles containing multicomponent liquid mixtures. Simple equipment and material models were applied to describe the process. In the plug-flow equipment model, a thin layer of particles moving forward and well mixed in the direction of the gas flow was regarded; thus, only the longitudinal changes of particle moisture content and composition as well as temperature along the dryer were considered. Concerning the material model, mass and heat transfer in a single isolated particle was studied. For grain wetted with a single liquid, mass and heat transfer within the particles was described by effective transfer coefficients. Assuming a constant effective mass transport coefficient and effective thermal conductivity of the wet particles, analytical solutions of the mass and energy balances were obtained. The variation of both transport coefficients along the dryer was taken into account by a stepwise application of the analytical solution in space intervals with non-uniform inlet conditions and averaged coefficients from previous locations in the dryer. Calculation results were verified by comparison with experimental data from the literature. There was fairly good agreement between experimental data and simulation but the results depend strongly on the correlation used to calculate heat and mass transfer coefficients.

 

For the case of particles containing a multicomponent liquid mixture dried in the vibrated fluidised bed dryer, interactive diffusion and heat conduction were considered the main mechanisms for mass and heat transfer within the particles. Assuming a constant matrix of effective multicomponent diffusion coefficients and thermal conductivity of the wet particles, analytical solutions of the diffusion and conduction equations were obtained. The equations for mass transfer were decoupled by a similarity transformation and solved simultaneously with conduction equation by the variable separation method. Simulations gave a good insight into the selectivity of the drying process and can be used to find conditions to improve aroma retention during drying.

 

Also, analytical solutions of the diffusion and conduction equations applied to liquid-side-controlled convective drying of a multicomponent liquid film were developed. Assuming constant physical properties of the liquid, the equations describing interactive mass transfer are decoupled by a similarity transformation and solved simultaneously with conduction equation and the ordinary differential equation that describes the changes in the liquid film thickness. Variations of physical properties along the process trajectory were taken into account as in the previous cases. Simulation results were compared with experimental data from the literature and a fairly good agreement was obtained. Simulations performed with ternary liquid mixtures containing only volatile components and ternary mixtures containing components of negligible volatility showed that it is difficult to obtain an evaporation process that is completely controlled by the liquid-side mass transfer. This occurs irrespective of the initial drying conditions.

 

Despite simplifications, the analytical solution of the material model gives a good insight into the selectivity of the drying process and is computationally fast. The solution can be a useful tool for process exploration and optimisation. It can also be used to accelerate convergence and reduce tedious and time-consuming calculations when more rigorous models are solved numerically.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2011. x, 54 p.
Series
Trita-CHE-Report, ISSN 1654-1081 ; 2011:44
Keyword
Analytical solution, Heat and mass transfer, Temperature and moisture distribution, Drying modelling, Multicomponent drying, Drying selectivity, Volatile retention, Ternary mixture, Drying of particulate materials, Vibrated fluidised bed dryer
National Category
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-34241 (URN)978-91-7501-038-0 (ISBN)
Presentation
2011-06-15, D41, KTH, Lindstedtsvägen 17, 1 tr, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20110614Available from: 2011-06-14 Created: 2011-05-30 Last updated: 2012-03-23Bibliographically approved

Open Access in DiVA

No full text

Scopus

Search in DiVA

By author/editor
Picado, ApolinarMartínez, Joaquín
By organisation
Transport Phenomena
Chemical Engineering

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 246 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf