Flow Path Spacer With Gradient Intervals For Membrane Elements
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Solution Overview
Problem
Flow path spacers in spiral membrane elements face a trade-off between achieving low pressure loss and reducing concentration polarization, as higher shear stress is typically associated with increased pressure loss, making it difficult to balance both effectively.
Innovation Solution
A flow path spacer design featuring a mesh structure with first and second linear portions extending in different directions, arranged at varying intervals to optimize shear stress and pressure loss, ensuring a balanced configuration that reduces concentration polarization while minimizing energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the flow path spacer uses a mesh structure with smaller intervals between linear portions to increase shear stress and reduce concentration polarization, then the pressure loss increases
Solution Approach 1:
The patent applies local quality by creating different interval sizes between linear portions at different locations within the flow path spacer. Specifically, the spacer includes a first region with a first interval, a second region with a second interval narrower than the first interval, and a third region with a third interval narrower than the second interval. This gradient structure allows different regions to provide different levels of shear stress: regions closer to the membrane surface (with narrower intervals) provide higher shear stress to reduce concentration polarization, while regions farther away (with wider intervals) maintain lower resistance to flow, thus reducing overall pressure loss. This spatial variation in structure quality resolves the contradiction between reducing concentration polarization and minimizing pressure loss.
2Loss of energy
If the flow path spacer uses larger intervals between linear portions to reduce pressure loss, then shear stress decreases and concentration polarization increases
Solution Approach 1:
The patent applies local quality by creating different interval sizes between linear portions at different locations within the flow path spacer. Specifically, the spacer includes a first region with a first interval, a second region with a second interval narrower than the first interval, and a third region with a third interval narrower than the second interval. This gradient structure allows different regions to provide different levels of shear stress: regions closer to the membrane surface (with narrower intervals) provide higher shear stress to reduce concentration polarization, while regions farther away (with wider intervals) maintain lower resistance to flow, thus reducing overall pressure loss. This spatial variation in structure quality resolves the contradiction between reducing concentration polarization and minimizing pressure loss.
3Ease of manufacture
If the flow path spacer uses a uniform mesh structure, then manufacturing is simplified, but it cannot simultaneously optimize both shear stress distribution and pressure loss
Solution Approach 1:
The patent applies parameter changes by systematically varying the interval parameter between linear portions across different regions of the flow path spacer. The spacer includes a first region with a first interval, a second region with a second interval narrower than the first interval, and a third region with a third interval narrower than the second interval. This controlled variation in the geometric parameter (interval width) allows optimization of the flow characteristics and shear stress distribution to enhance water permeation efficiency while still maintaining a manufacturable mesh structure through established fabrication techniques.
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 spacer achieves a good balance between shear stress and pressure loss, enhancing water permeation by reducing concentration polarization and energy requirements, and preventing biofouling in spiral membrane elements.
Implementation Method 1
How likely a concentration polarization layer is to be formed can be expressed by the magnitude of shear stress acting on a separation membrane. The higher shear stress acting on a separation membrane is, the more likely a solute is to be washed away from the vicinity of the surface of a separation membrane.
Implementation Method 2
A concentration polarization layer is a layer having a high concentration of a solute, such as ions and salts, that cannot permeate a separation membrane
Implementation Method 3
A concentration polarization layer increases an osmotic pressure in the vicinity of the surface of a separation membrane and decreases the amount of permeated water.
Data Source
AI summary
A flow path spacer (13) of the present disclosure includes a plurality of first linear portions (21) and a plurality of second linear portions (22). There are a first pair (P1), a second pair (P2), and a third pair (P3), the first pair (P1) is at least one selected from a pair of the first linear portions (21) adjacent to each other and disposed at a first interval (W1) and a pair of the second linear portions (22) adjacent to each other and disposed at a first interval (W1), the second pair (P2) is at least one selected from a pair of the first linear portions (21) adjacent to each other and disposed at a second interval (W2) narrower than the first interval (W1) and a pair of the second linear portions (22) adjacent to each other and disposed at a second interval (W2) narrower than the first interval (W1), and the third pair (P3) is at least one selected from a pair of the first linear portions (21) adjacent to each other and disposed at a third interval (W3) narrower than the second interval (W2) and a pair of the second linear portions (22) adjacent to each other and disposed at a third interval (W3) narrower than the second interval (W2).