Capillary Dialyzer End Cap Flow Optimization
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Solution Overview
Problem
Current capillary dialyzers for blood purification face challenges in performance, efficiency, reliability, safety, and handling, with a need for improved design and functionality to enhance their capabilities.
Innovation Solution
The capillary dialyzers feature optimized housings and end caps with specific geometries and materials, along with hollow fiber membranes composed of 80-99 wt% polyethersulfone and 1-20 wt% polyvinylpyrrolidone, providing enhanced filtration properties and structural support, and a support ring design with ridges and through bores for improved interlock and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional end cap designs are used, then manufacturing is simpler, but flow characteristics and filtration efficiency are insufficient
Solution Approach 1:
The end cap incorporates a funnel-shaped recess with specific geometric parameters (angle α between 45-90°, depth h, diameter D) that create optimized flow patterns in the blood compartment. This localized geometric optimization improves blood flow distribution and filtration efficiency without requiring complex changes to the entire dialyzer structure
Solution Approach 2:
The invention specifies precise parameter ranges for the funnel-shaped recess (angle α, depth h, diameter D) to optimize flow characteristics. By carefully controlling these geometric parameters, the design achieves improved filtration efficiency while maintaining manufacturability through standard molding processes
2Productivity
If hollow fiber membranes with higher performance are used, then ultrafiltration rates increase, but manufacturing precision requirements increase
Solution Approach 1:
The hollow fiber membranes are constructed as composite materials with polyethersulfone (80-99 wt%) and polyvinylpyrrolidone (1-20 wt%). This composite structure provides both high ultrafiltration performance and manufacturability, as the polymer blend can be processed using conventional phase inversion techniques while achieving controlled pore structures and high flux rates
Solution Approach 2:
The invention specifies precise compositional parameters for the hollow fiber membranes (polymer ratios, molecular weights, pore sizes) to optimize ultrafiltration performance. These parameter specifications enable manufacturers to produce high-performance membranes with consistent quality through controlled phase inversion processes
3Reliability
If support rings with better mechanical interlock are used, then structural stability improves, but device complexity increases
Solution Approach 1:
The support ring is designed as a thin-walled structure with radial ridges that provide mechanical interlocking with the hollow fiber bundle. This thin-film design with optimized ridge geometry achieves high mechanical stability and secure fiber retention while minimizing material usage and maintaining ease of assembly
Solution Approach 2:
The support ring incorporates radial ridges that segment the circular cross-section into multiple zones. This segmentation provides multiple interlocking points for the hollow fiber bundle, enhancing mechanical stability and fiber retention without requiring a completely complex structural design
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 optimized design results in improved filtration efficiency, reduced residual blood volume, and increased ultrafiltration rates, with effective membrane surface area and pressure handling, enhancing overall performance and reliability in blood purification processes.
Implementation Method 1
a bundle of semi-permeable hollow fiber membranes (2) disposed within the internal chamber
Implementation Method 2
enhanced filtration properties
Implementation Method 3
hollow fiber membranes composed of 80-99 wt% polyethersulfone and 1-20 wt% polyvinylpyrrolidone
Implementation Method 4
enhanced filtration properties
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
Capillary dialyzer comprising: a) a housing (1); b) a bundle of semi-permeable hollow fiber membranes (2); c) end wall means (3) supporting the first and second ends of the hollow fiber membranes; d) a first end cap (4a) covering the first end of the housing and a second end cap (4b) covering the second end of the housing; e) an inlet (5) and an outlet (5); f) support rings (6); and g) sealing rings (7) interposed between the end wall and the first end cap (4a) and between the end wall and the second end cap (4b), respectively; wherein the circular groove of the end cap (4a, 4b) which receives the wall of the housing (1) comprises indentations for creating a fluid connection between the inside of the capillary dialyzer and its exterior when the end caps (4a, 4b) are mounted on the housing (1) but have not yet been welded to the housing (1).