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machine, it has a directly proportional linear, because its performance depends
little on the forming tool of resistance. As the extension of this zone are reduced
ripple, and a screw effective length sufficiently large dispensing area can be
neglected. Anomaly in viscosity slightly reduces the effect of screw speed to
temperature fluctuations. Improving the performance leads to a reduction of
temperature fluctuations of the amplitude and increased product pressure
pulsation amplitude.
Thus, the dependences of the thermodynamic characteristics - pressure and
temperature of the product in area before matrix single- and twin-screw
extruders - from the parameters of the process.
The rheological and kinetic studies on them obtain the optimum parameters
of the process and the basis for mathematical models of temperature changes
(pressure) and the melt flow rate of the product in the form of channels of the
matrix, the matrix before the zone and channel metering screw extruder zone.
Mathematical model of non-isothermal flow abnormally - viscous medium
in the area of one dosing screw extruder included the continuity equation,
viscous fluid motion, heat balance equation, which takes into account the
rheological properties of the food mixture. The formulation is made according to
the accepted assumptions:
- Take into account the existence of anomalies of viscosity;
- The mutual influence of the circulating currents and progressive;
- The presence of heat released as a result of viscous friction;
- Taking over the established and did not consider the force and mass
inertia;
- Gradients of velocity components.
Heating of the melt of the product only by the dissipation of mechanical
energy leads to a maximum temperature rise at the surface of the screw.
Moreover, the upper movable wall (Tso), it may be lower than that of the screw
20. on. . K. viscous medium 40 in the wall area temperature increases due to
rearrangement of the temperature field and its cooling effect in the central
portion of the channel, which is a consequence of the adiabatic expansion.
Smaller values of the speed of the screw 32 at the surface are explained by
the presence of the counter. Higher product pressure at the end of the metering
zone of the extruder (zone in the matrix before), the greater the velocity tend to
negative values of - the increasing backflow effect.
Mathematical model of the extrusion process in the flow of viscous fluid in
the matrix before the zone of the extruder. For this matrix before extruder zone
is represented in a spherical coordinate system in the form of a truncated cone,
which is pressed through the grain mixture extrudable. Previous matrix zone
conditionally divided into two parts, depending on the position of the tip of the
screw and the flow of rheological fluid in the cone (I band) and between two
coaxial cones (II band).
In the study fields of speeds characterizing the performance of the extruder,
and the pressure distribution law in a moving medium, affecting the quality of
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