Continuous Twin-Screw Mixer Extensional Flow Design
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Solution Overview
Problem
Existing continuous mixers struggle to efficiently mix materials with large viscosity differences between dispersed and matrix phases, as they rely on shear forces that often result in thermal deterioration and insufficient mixing.
Innovation Solution
A continuous mixer design featuring a pair of mixing rotors rotating in different directions, with an inter-rotor clearance that generates extensional flow by ensuring the smallest clearance between mixing portions, allowing materials to be stretched and dispersed effectively within the matrix phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large shear force is applied to the material in existing continuous mixers, then mixing performance is improved, but thermal deterioration occurs and energy efficiency decreases
Solution Approach 1:
The invention changes the fundamental flow type parameter from shear flow to extensional flow by adjusting the inter-rotor clearance to a specific range (0.01 to 0.05 times the rotor diameter). This parameter change enables effective mixing of materials with large viscosity differences without generating excessive heat, thereby resolving the contradiction between mixing performance and thermal deterioration.
2Reliability
If shear force is applied to mix materials with large viscosity difference between dispersed phase and matrix phase, then mixing is attempted, but the shear force is expended to rotate the dispersed phase rather than achieving effective dispersion
Solution Approach 1:
The invention changes the flow type parameter from shear flow to extensional flow by precisely controlling the inter-rotor clearance. Extensional flow directly deforms and disperses the dispersed phase through stretching forces, preventing energy waste on rotating the dispersed phase and achieving effective dispersion with higher energy efficiency.
3Reliability
If the inter-rotor clearance is reduced to generate extensional flow, then mixing of materials with large viscosity difference is achieved, but device complexity increases
Solution Approach 1:
The invention identifies a specific parameter range for inter-rotor clearance (0.01 to 0.05 times the rotor diameter) that generates effective extensional flow. By defining this concrete parameter range, the invention balances mixing capability with manufacturability, avoiding excessive device complexity while achieving reliable mixing of difficult materials.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reliably mixes materials with high viscosity differences, enhancing dispersibility and reducing gel formation, while minimizing thermal deterioration and energy requirements.
Implementation Method 1
setting the inter-rotor clearance to a dimension which allows an extensional flow to be generated in the material between the mixing portions makes it possible to actually reliably mix a mixing resistant material
Implementation Method 2
The mixing flights form small tip clearances between them and the inner peripheral surface of the barrel respectively, causing a largely shear deformation in a material passing through the tip clearances
Data Source
AI summary
A continuous mixer includes a barrel with a hollow interior, and a pair of mixing rotors housed in the barrel and that rotate in mutually different directions, each mixing rotor including a mixing portion with plural mixing flights formed about an axial center of the mixing rotor and projecting radially outward. The mixing rotors have a center distance therebetween smaller than a rotation outer diameter of each of the respective mixing flights. An inter-rotor clearance, which is the smallest clearance between the mixing portions at each rotation phase of the mixing rotors in a cross section perpendicular to axial directions of the both mixing rotors, has a dimension allowing an extensional flow to be generated in a material passing through the inter-rotor clearance. The continuous mixer can reliably and efficiently mix a material having a large viscosity difference between a dispersed phase and a matrix phase.