Unterschiede

Hier werden die Unterschiede zwischen zwei Versionen angezeigt.

--- en:grundlagenhandbuch:entgasungsoberflaechenberechnung [2026/02/09 20:57] – [Modified model for the calculation of the free surface] neelest
+++ en:grundlagenhandbuch:entgasungsoberflaechenberechnung [2026/08/03 13:36] (aktuell) – [Degassing efficiency of the process] paal
@@ Zeile 1: / Zeile 1: @@
 ====== Calculation of the degassing surface======
-===== Material degradation and degassing =====
+==== Material degradation and degassing ====
   * Thermal (oxidative, mechanical)
@@ Zeile 27: / Zeile 27: @@
 Decisive for a successful degassing are the applied vacuum and the surface of the melt in the screw channel.
-===== Model for calculating the free surface =====
+==== Model for calculating the free surface ====
 The free surface is composed of the melt pool and melt film, which are constantly renewed by the continuous rotation of the screws.
@@ Zeile 59: / Zeile 59: @@
 The Schuler model is characterized by the consideration of the free surfaces in the contact zone of both screws and the inclusion of the screw base in the calculation of the film. The constant height of the channel leads to a decisive disadvantage in the calculation. To take the channel height into account, the modification of the Schuler model is necessary.
-===== Modified model for the calculation of the free surface =====
+==== Modified model for the calculation of the free surface ====
 During the modification, it is assumed that the polymer is completely melted in the last third of the screw channel and there's a bubble-free layer flow. The essential difference is that here the height of the melt is present as a function of the filling degree, as shown in equation 5.
@@ Zeile 105: / Zeile 105: @@
 ===== Degassing efficiency of the process =====
-The degassing efficiency is evaluated with the degassing reference parameter of Schuler (Equation 1. In this case taken place the determination for wetting and non-wetting polymer.
+The degassing performance can be calculated using the following equation:
-$$\frac{c_{Start} - c_{End}}{c_{Start} - c_{Gleichgewicht}} = \frac{\left(\frac{A_{POOL}}{t_{POOL}} + \frac{A_{FILM}}{t_{FILM}} + \frac{A_{GRUND}}{t_{GRUND}}\right)}{\dot{m}} \tag{Equation 1}$$
+$$\eta^* = \frac{c_{Start} - c_{End}}{c_{Start} - c_{Equilibrium}} = 2\rho\sqrt{ \frac{ D }{ \pi } } \frac{\left(\frac{A_{POOL}}{\sqrt{t_{POOL}}} + \frac{A_{FILM}}{\sqrt{t_{FILM}}} + \frac{A_{GROUND}}{\sqrt{t_{GROUND}}}\right)}{\dot{m}} \tag{8}$$
 After transposing of the equation can be the end concentration of low molecular component determined. Thereby is it possible to take a statement about the degassing efficiency.
+The degassing efficiency is evaluated with the degassing reference parameter of Schuler (Equation 9).
-For wetting polymer is the Equation 2and for non-wetting polymer is the Equation 3 used.
+$$\frac{c_{Start} - c_{End}}{c_{Start} - c_{Equilibrium}} \sim \frac{\left(\frac{A_{POOL}}{\sqrt{t_{POOL}}} + \frac{A_{FILM}}{\sqrt{t_{FILM}}} + \frac{A_{GROUND}}{\sqrt{t_{GROUND}}}\right)}{\dot{m}} \tag{9}$$
-$$EK_{Benetzend} = \frac{\left(\frac{A_{POOL}}{t_{POOL}} + \frac{A_{FILM}}{t_{FILM}} + \frac{A_{GRUND}}{t_{GRUND}}\right)}{\dot{m}} \tag{Equation 2}$$
+In this case taken place the determination for wetting and non-wetting polymer. For wetting polymer is the Equation 10 and for non-wetting polymer is the Equation 11 used.
-$$EK_{Nicht-Benetzend} = \frac{\left(\frac{A_{POOL}}{t_{POOL}} + \frac{A_{FILM}}{t_{FILM}}\right)}{\dot{m}} \tag{Equation 3}$$
+$$EK_{Wetting} = \frac{\left(\frac{A_{POOL}}{\sqrt{t_{POOL}}} + \frac{A_{FILM}}{\sqrt{t_{FILM}}} + \frac{A_{GROUND}}{\sqrt{t_{GROUND}}}\right)}{\dot{m}} \tag{10}$$
+$$EK_{Non-Wetting} = \frac{\left(\frac{A_{POOL}}{\sqrt{t_{POOL}}} + \frac{A_{FILM}}{\sqrt{t_{FILM}}}\right)}{\dot{m}} \tag{11}$$
 The difference between both equation is that the surface area und renewal time at screw root is neglected, because in non-wetting case are not melt at screw root available.