Abonnement à la biblothèque: Guest

ISSN Online: 2377-424X

ISBN CD: 1-56700-226-9

ISBN Online: 1-56700-225-0

International Heat Transfer Conference 13
August, 13-18, 2006, Sydney, Australia

COMBINED THERMAL PRESSURE FORMING OF STARCH SUSPENSIONS

Get access (open in a dialog) DOI: 10.1615/IHTC13.p11.40
12 pages

Résumé

Integral enthalpy balance model was applied for the description of the thermal forming process of starch based suspensions in a closed mould. The model parameters were identified from experiments with the apparatus ensuring combined surface heating and direct volumetric ohmic heating (alternating current 50 Hz and electrodes attached at the mould wall). Temperatures inside a thin plate of the heated material were measured by a string-form thermocouple and pressures at the wall were recorded by a pressure transducer. Results confirm previously reported conclusion that the temperature of material is determined by the steam pressure during the second and the third stage of water evaporation. Preliminary experiments indicate, that the direct ohmic heating affects mostly the first stage of heating, because electrical conductivity of starch suspension decreases during the phases of water evaporation. While the simple integral model is useful for prediction of temperatures and the mean pressure, a 2D finite element model is aimed to the description of sample expansion in more complicated geometries of moulds (an approximately triple increase of volume was recorded in experiments with potato starch suspensions).