Oblique Fold Filter Element for Low Pressure Drop
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Solution Overview
Problem
Cassette filters and filter cartridges face challenges in reducing pressure difference and improving filtration performance, particularly when using materials like glass fiber paper that are not dimensionally stable and may be brittle, leading to issues with sealing and potential leaks.
Innovation Solution
The use of a filter element with special oblique folds, characterized by a trapezoidal cross-section and a ratio of fold peaks and valleys that optimizes filtration, reduces the sealed area between adjacent filter elements, and allows for direct bonding without additional elements, thereby minimizing pressure drop and enhancing filtration efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If glass fiber paper is used as the filter medium, then filtration efficiency is improved, but mechanical strength is reduced leading to risk of destruction
Solution Approach 1:
The filter element is divided into multiple pleated sections that can be interconnected. This segmentation allows the use of thinner, more efficient filter media while maintaining structural integrity through the modular design and interconnection mechanism.
Solution Approach 2:
The filter element combines glass fiber paper with a supportive framework including pleat boards and interconnection structures. This composite approach allows the filter medium to provide high filtration efficiency while the framework provides the necessary mechanical strength.
2Reliability
If wider seals are used between adjacent filter elements, then sealing reliability is improved, but pressure drop across the filter increases
Solution Approach 1:
The seal width is made variable through the pleat design, where the sealed area changes dynamically based on the pleat configuration. This allows optimized sealing at critical points while maintaining larger open areas for airflow, reducing overall pressure drop.
Solution Approach 2:
The pleat geometry parameters are optimized to achieve the right balance between seal width and open area. By carefully controlling pleat depth, spacing, and angle, the design achieves reliable sealing with minimal impact on airflow and pressure drop.
3Loss of energy
If narrower seals are used between adjacent filter elements, then pressure drop is reduced, but sealing reliability deteriorates leading to potential leaks
Solution Approach 1:
The filter element is segmented into pleated sections with interconnection features that provide multiple sealing points. This segmentation allows narrow individual seals while maintaining overall sealing reliability through the cumulative effect of multiple sealed joints.
Solution Approach 2:
The sealing approach moves from relying solely on seal width in one dimension to utilizing the three-dimensional pleat structure. The pleats create multiple sealing surfaces and paths, providing reliable sealing even with narrow individual seal widths.
4Stress or pressure
If the edge area of the cover is increased, then pressure difference is reduced, but the opening area for air flow is reduced
Solution Approach 1:
The filter element design with variable pleat height creates a dynamic flow path that allows optimized pressure distribution. The pleat configuration adapts the flow area distribution to reduce pressure difference while maintaining adequate opening area.
Solution Approach 2:
The pleat geometry parameters are optimized to control the flow path and pressure distribution. By adjusting pleat depth, spacing, and angle, the design achieves reduced pressure difference while maintaining sufficient opening area for air flow.
Data Source
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AI summary
The invention relates to a filter element (10) with a pleated filter medium (1), wherein the filter medium (1) is provided with a special pleat (1.3), namely an oblique, i.e., non-parallel pleat. The invention also relates to a cassette filter (200) with such filter elements and a filter cartridge (300) with such a filter element. The use of the filter elements advantageously improves the filtration performance of cassette filters and filter cartridges.