Thin-Wall Helical Duct Forming for Tight-Radius Air Separation
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Solution Overview
Problem
Conventional methods for forming tightly coiled ducts for centrifugal air separation face challenges such as wrinkling, cracking, and distortion, particularly with thin-wall metal tubing, due to the small radius of curvature required for effective gas separation.
Innovation Solution
A method involving a helical coil toolset with a helically grooved mandrel and an entry block to bend thin-wall tubing into a tightly coiled helical duct with a radius of curvature less than four times the outside tube diameter, using a sliding fit and support material to prevent distortion, while maintaining a smooth interior finish for laminar gas flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thin-wall metal tubing is bent with a small radius of curvature to achieve tightly coiled ducts for effective gas separation, then the centrifugal air separation efficiency is improved, but the tubing integrity deteriorates due to wrinkling, cracking, and flattening
Solution Approach 1:
The tubing is pre-filled with support material (sand, gravel, or other granular materials) before bending. This preliminary action provides internal support to the thin-wall tubing during the bending process, preventing wrinkling, cracking, and flattening while allowing the tube to be bent to a radius of curvature less than five times its outside diameter, thereby achieving the tightly coiled configuration needed for effective centrifugal air separation
Solution Approach 2:
Support material acts as an intermediary substance inserted inside the tubing. This intermediary provides structural reinforcement during the bending operation, enabling the thin-wall tube to withstand the compressive and tensile stresses of tight bending without compromising its integrity. The support material is later removed after bending, leaving the tube in its tightly coiled helical shape
2Productivity
If the radius of curvature is reduced to less than five times the outside diameter for effective separation, then the gas separation performance is improved, but the manufacturing difficulty increases due to conventional bending limitations
Solution Approach 1:
The tubing is pre-filled with support material before bending, which fundamentally changes the manufacturing feasibility. This preliminary preparation allows conventional bending equipment to successfully form tight radii of curvature (less than five times the outside diameter) that would normally be impossible with thin-wall tubing, thereby enabling production of ducts with the dimensions needed for high-efficiency gas separation
Solution Approach 2:
The invention changes the physical state and properties of the tubing system by introducing support material inside the tube. This parameter change (adding internal support) transforms the tube from a state where tight bending causes failure to a state where tight bending can be successfully performed, thereby enabling manufacturing of ducts with radius of curvature less than five times the outside diameter
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 method effectively forms tightly coiled helical ducts without significant wrinkling or cracking, ensuring efficient gas separation by maintaining the integrity of the tubing and promoting laminar flow for effective carbon dioxide removal in enclosed environments.
Implementation Method 1
Centrifugal air separation separates flowing gas based on the molecular weight of the gas' constituents by passing the input gas through a tightly coiled duct... As the gas travels along the coiled duct in a generally laminar manner, the input gas stratifies according to the molecular weight of the gas components
Implementation Method 2
the input gas flows at relatively high speed through a tightly coiled duct, causing the gas to follow the duct's coiled path (generally a helical path). As the gas travels along the coiled duct in a generally laminar manner
Data Source
AI summary
Methods for forming thin wall tubing into a tightly-coiled helical duct comprise selecting a thin wall tube with an outside tube diameter and a wall thickness that is less than 15% of the outside tube diameter; and bending the thin wall tube to form the tightly-coiled helical duct so that an outside duct diameter of the tightly-coiled helical duct is less than four times the outside tube diameter.