Chair:
Leandro Soares de Oliveira
Departamento de Engenharia Química
- Universidade Federal de Minas Gerais
ON LINE SUPERVISION AND THREE-DIMENSIONAL ANALYSIS OF A STOVE DRYING PROCESS
Paulo Ignácio Fonseca
de Almeida - pignacio@power.ufscar.br
Universidade Federal de
São Carlos, Departamento de Engenharia Química
13565-905 São Carlos
, SP - Brasil
Carlos Henrique Novaga Alves
- chna@hotmail.com
Universidade Federal de
São Carlos, Departamento de Engenharia Química
13565-905 São Carlos
, SP - Brasil
Natural drying by atmosphere
evaporation is not efficient or convenient for industrial process. In alimentary
production the tendency is to confine the products in stoves or in closed
carriers for protect the product against atmosphere contamination and minimize
its looses. In the present work an on line vision system supervises the
product shrinkage (potato cubes) during drying process in a natural convective
stove. A laser illumination system permitted three-dimensional images and
its computer analysis. The results were correlated with date from an on-line
strain gage specially mounted over the stove. The use of thee-dimensional
images is adopted to overcome the error produced by two-dimensional area
coincidence in the images obtained from an orderliness product drying process.
The result show to be valid uses the laser illumination system for estimates
the shadow dimension of the products together to the traditional two-dimensional
image obtained by on line vision systems.
CONVECTIVE LAMINAR FLOW OF FOOD ADITIVIES SOLUTIONS IN CIRCULAR ENTRANCE REGION
Sérgio R. Fontes -
srfontss@fcav.unesp.br
UNESP - FCAV - Via Prof.
Paulo Donato Castellane, s/n
14870-000 - Jaboticabal,
SP, Brasil
Carlos A. Gasparetto - gasparetto@ceres.fea.unicamp.br
UNICAMP - FEA - Cx. P. 6121
13083-970 - Campinas, SP,
Brasil
This is an investigation of non isothermal and non-Newtonian laminar flow in the entrance region of short tubes. The flow is steady, incompressible and tube wall has constant temperature with heating and cooling. Experimental work was conducted using water solutions of Xanthan and Guar gums which exhibited pseudoplastic behavior. Experiments lie in the ranges: 2x10 -04 < Gz -1 < 10 -02 , 300 < Pr < 1000, 30 < Re < 400 and 30,9 < L/D < 135,8. Results were reported as non-dimensional correlations allows practical calculations of Nusselt, Graetz, L/D, Stanton and the friction coefficients. The tendency of the results are compatible with the literature.
Keywords: Entrance region;
Convective flow; Guar gum; Xanthan gum.
ANALYTICAL APPROACH SOLUTION FOR ESTIMATE OF TRANSMEMBRANE FLUX IN CROSSFLOW PROCESSES
Sérgio R. Fontes -
srfontss@fcav.unesp.br
UNESP/FCAV - Via Prof. Paulo
Donato Castellane, s/n
14870-000 - Jaboticabal,
SP, Brasil
Studies have been carried out on micro and ultrafiltration for macromolecular solutions. This complex flow in tubular geometry does not allow accurate analytical solutions to be developed. Approaches to the modelling of crossflow have been numerous highly varied in degree of complexity, and is of great interest in order to design the process and to reach the best transmembrane flux. In this work the fluid flow through a porous tube is modeled from the differential mathematical formulation presented by Zydney (1997), and the equation it approaches the fluid flow with an established velocities profiles, being an entrance region similar to Graetz problem. An analytical solution is presented for polinomial functions, and comparison is carried among experimental rate flux and analytical data, and good agreement is observed.
Keywords: Mathematical modeling;
Crossflow; Mass transfer; Xanthan gum; Guar gum.
STUDY OF CONVECTIVE DRYING APLLE SLICES KINETICS. EFFECT ON SHRINKAGE
Schultz, E.L. - emersonleo@hotmail.com
Quadri, M.G.N. - mara@enq.ufsc.br
Universidade Federal de
Santa Catarina, Departamento de Engenharia Química
Cx. P. 276 - 88040-900 -
Florianópolis, SC, Brasil
Quadri, M.B. - m-quadri@enq.ufsc.br
Universidade Federal de
Santa Catarina, Departamento de Engenharia Química
Cx. P. 276 - 88040-900 -
Florianópolis, SC, Brasil
Drying rate is controlled by different factors that change during the drying process. The time of the process and energy costs can be reduced using variable conditions. Therefore, the influence of different air conditions on the drying rate has been analysed in this work. It was found that shrinkage depends only on the material humidity content.
Keyword: Drying kinectics,
Aplle slices, Shrinkage