scholarly journals Investigations Concerning the Residence Time Distribution of Twin-Screw-Extrusion Processes as Indicator for Inherent Mixing

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 207 ◽  
Author(s):  
Jens Wesholowski ◽  
Andreas Berghaus ◽  
Markus Thommes
Keyword(s):  
Residence Time ◽  
Mass Flow ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Dispersion Model ◽  
Model Parameters ◽  
Twin Screw Extrusion ◽  
Characteristic Model ◽  
Screw Extrusion ◽  
Twin Screw

Over recent years Twin-Screw-Extrusion (TSE) has been established as a platform technology for pharmaceutical manufacturing. Compared to other continuous operation, one of the major benefits of this method is the combination of several unit operations within one apparatus. Several of these are linked to the Residence Time Distribution (RTD), which is typically expressed by the residence time density function. One relevant aspect for pharmaceutical processes is the mixing capacity, which is represented by the width of this distribution. In the frame of this study the influence of the mass flow, the temperature and the screw-barrel clearance were investigated for a constant barrel load (specific feed load, SFL). While the total mass flow as well as the external screw diameter affected the mixing performance, the barrel temperature had no influence for the investigated range. The determined results were additionally evaluated with respect to a fit to the Twin-Dispersion-Model (TDM). This model is based on the superimposition of two mixing functions. The correlations between varied process parameters and the obtained characteristic model parameters proved this general physical view on extrusion.

Residence Time Distribution and Barrel Fill in Pet Food Twin-Screw Extrusion Cooking

2000 ◽  
Vol 77 (2) ◽  
pp. 220-222 ◽  
Author(s):  
S. M. Mahungu ◽  
K. A. Drozdek ◽  
W. E. Artz ◽  
J. F. Faller
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Extrusion Cooking ◽  
Pet Food ◽  
Twin Screw Extrusion ◽  
Screw Extrusion ◽  
Twin Screw

Modeling the Residence Time Distribution of a Non-Intermeshing Twin Screw Extruder

1995 ◽  
Vol 10 (2) ◽  
pp. 111-119 ◽  
Author(s):  
M. Thompson ◽  
J. P. Puaux ◽  
A. N. Hrymak ◽  
A. E. Hamielec
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Twin Screw Extruder ◽  
Screw Extruder ◽  
Twin Screw

Influence of Fluid Viscosity on the Residence Time Distribution of Micro Reactors Made of LTCC

2008 ◽  
Author(s):  
G. A. Groß ◽  
S. Schneider ◽  
B. Schleif ◽  
J. M. Ko¨hler
Keyword(s):  
Residence Time ◽  
Time Distribution ◽  
Residence Time Distribution ◽  
Dispersion Model ◽  
Internal Diameter ◽  
Fluid Viscosity ◽  
Complex Relation ◽  
Micro Flow ◽  
Micro Reactors ◽  
Micro Mixer

The residence time distribution of LTCC microreactors was investigated depending on flow rates and fluid viscosities. A pulse trace experiment was used for monitoring the tracer signals before and behind the microreactors. The tracer signals were measured by use of micro flow-through photometers without disturbing the liquid flow. Therefore, the micro photometers were mounted directly onto FEP tubings. The residence time distribution (RTD) was determined by calculation of the dispersion model using the inlet and outlet tracer profiles. The RTD of a LTCC micro mixer and a LTCC plain meandered channel mixer were determined in the flow rate range between 50 μL/min and 3 000 μL/min using water and aqueous glycerol mixtures up to a glycerol content of 50%. Received data were compared with a PTFE tube (1 mm internal diameter) as reference. A complex relation of determined RTDs between the Reynolds number (Re) and the fluid viscosities was found. A significant non-monotonous effect of the fluid viscosity was observed. The RTD as well as the tailing behavior indicates clearly viscosity-dependent changes in the fluid regime and transport mechanisms.

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