Date of Award
January 2016
Degree Type
Dissertation
Degree Name
Doctor of Philosophy (PhD)
Department
Agricultural and Biological Engineering
First Advisor
Martin R Okos
Committee Member 1
Osvaldo H Campanella
Committee Member 2
Bruce R Hamaker
Committee Member 3
Ganesan Narsimhan
Abstract
Understanding rheology of raw materials and the numerous transformations they undergo is an essential aspect of modeling and predicting extrusion conditions. Both off-line capillary rheometry and in-line extruder fed rheometry techniques have been used to model rheology of materials during extrusion. Investigations on use of an off-line capillary rheometer to model apparent viscosity of full fat soy flours revealed inability of the capillary rheometer to handle food/biological materials high in oil content (20%) at high temperature (80C) and low moisture content (15% wet basis). The lack shear degradation in the capillary rheometer also resulted in over-prediction of corn flour viscosities at high temperatures (80 to 120C), shear rates (1 to 100 s-1) and low moisture contents (35 to 40%). A novel two-opening die attached to a small scale extruder operating at 100 to 300 rpm was used to measure in-line viscosities of cornmeal at 32.5 to 37.5% moisture during extrusion. Comparison of off-line versus in-line cornmeal viscosities at similar conditions consistently indicated that for food/biological materials sensitive to shear degradation, in-line viscosities were lower. Pasting property measurement revealed differences in material transformation which could be used to explain differences between techniques. Mechanistic model for the small-scale
Recommended Citation
Ponrajan, Amudhan, "INVESTIGATING RHEOLOGICAL TECHNIQUES TO MODEL AND PREDICT OPERATING CONDITIONS OF A SINGLE SCREW EXTRUDER WITH INTERNAL RESTRICTIONS" (2016). Open Access Dissertations. 1267.
https://docs.lib.purdue.edu/open_access_dissertations/1267