Toroidal Impeller Geometry for Low-Shear Bioreactor Mixing
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Solution Overview
Problem
Existing impellers in bioreactors generate high shear stress, which is detrimental to sensitive microorganisms and cells, limiting mixing efficiency and uniformity in large tank applications.
Innovation Solution
Toroidal impellers with looped blade members that minimize shear stress and promote axial flow, reducing energy consumption and enhancing mass transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional impellers are used to achieve efficient mixing, then mixing efficiency is improved, but shear stress on cells increases
Solution Approach 1:
The impeller blades are designed with a toroidal (doughnut-shaped) geometry featuring curved surfaces and looped configurations. This curvature allows the blades to move fluid in a circular pattern that generates mixing while minimizing turbulent eddies and vortex formation, thereby reducing shear stress on sensitive cells while maintaining mixing efficiency.
Solution Approach 2:
The patent modifies the geometric parameters of the impeller blades, including the looped configuration, blade angle, and toroidal shape dimensions. These parameter changes transform the flow characteristics from high-shear traditional patterns to low-shear toroidal flow patterns, achieving both efficient mixing and reduced cellular damage.
2Quantity of substance
If vigorous mixing is applied to reduce gradients, then mass transfer is improved, but shear stress on microorganisms increases
Solution Approach 1:
The toroidal blade geometry creates smooth, circular flow paths that enhance mass transfer through continuous circulation and gentle mixing. The curved surfaces promote uniform distribution of nutrients and gases without generating the violent turbulence and small-scale eddies that cause shear damage to microorganisms.
3Productivity
If traditional impeller designs are used, then mixing capability is achieved, but energy losses increase
Solution Approach 1:
The toroidal shape of the blades optimizes fluid dynamics by creating smooth, continuous flow patterns that reduce turbulence and minimize energy dissipation. The looped configuration ensures that energy is efficiently transferred to the bulk fluid for productive mixing rather than being lost to violent eddies and vortexes.
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
The toroidal impellers provide efficient mixing with reduced shear stress, improving uniformity and energy efficiency while maintaining optimal conditions for cell growth and product production.
Implementation Method 1
Impellers are rotating devices within the bioreactor tank that generate turbulence and induce fluid circulation
Implementation Method 2
Impellers are rotating devices within the bioreactor tank that generate turbulence and induce fluid circulation
Data Source
AI summary
A bioreactor can include a vessel defining an interior volume; a motor; a rotatable shaft assembly connected to the motor and extending within the interior volume along a longitudinal axis; one or more toroidal impellers mounted onto the shaft assembly and disposed within the interior volume, the toroidal impeller including a plurality of blade members supported by a hub that each define a radially bounded passageway extending along a second axis disposed at an oblique angle to the longitudinal axis.