Flexible Bioprocess Bag Panel Design for Wrinkle Reduction
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Solution Overview
Problem
Flexible bioprocess bags used in cylindrical bioreactors often develop wrinkles and stress concentrations when filled, leading to stagnant fluid zones and reduced heat transfer, as they do not conform well to the vessel shape, causing fluid accumulation and inefficiencies in bioreactor operations.
Innovation Solution
A flexible bioprocess bag design featuring sealed flexible panels that form a bottom and side surface, with bent triangular or quadrilateral parts that minimize film folds and ensure a close fit within cylindrical vessels, reducing wrinkles and enhancing heat transfer by maintaining a thin film layer and preventing air pocket formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a flexible bag is provided inside a cylindrical vessel, then the bag can be used as a disposable liner for bioreactor operations, but wrinkles and stress concentrations develop in the liner due to poor form matching
Solution Approach 1:
The flexible bag is divided into multiple panels (typically 3-6 panels) that are sealed together to form the cylindrical structure. This segmentation allows the bag to better conform to the vessel shape while maintaining structural integrity and reducing wrinkles compared to a single-piece construction.
Solution Approach 2:
The bag is designed with a cylindrical geometry that matches the curvature of the bioreactor vessel. The panels are configured to form a curved surface that closely follows the vessel's cylindrical shape, minimizing unsupported regions and stress concentrations.
2Device complexity
If the flexible bag does not conform well to the vessel shape, then there are unsupported regions, but this causes stagnant fluid zones and fluid accumulation in wrinkles
Solution Approach 1:
The bag design ensures uniform distribution of fluid pressure and stress across all panels by creating a symmetrical cylindrical structure. This equipotential distribution prevents localized stress concentrations and eliminates dead zones where fluid could stagnate, maintaining consistent mixing efficiency throughout the vessel.
3Temperature
If a close fit between the vessel and liner is provided, then heat transfer is improved, but this requires precise geometric matching of the flexible bag to the cylindrical vessel
Solution Approach 1:
The cylindrical panel design creates a universal geometry that can be adapted to different vessel sizes and configurations. The same basic panel structure can be scaled to match various diameters, reducing the need for custom geometric designs while maintaining optimal heat transfer contact with the vessel wall.
Data Source
AI summary
A flexible bioprocess bag comprising a number of flexible panels which are sealed to each other such that when the bag is filled they form at least a bottom of the bag and a side surface of the bag, wherein one of the flexible panels is called a bottom panel and when the bag is filled said bottom panel will constitute the bottom of the bag and parts of the side surface of the bag, said parts of the side surface being bent side parts of the bottom panel.