Permeation Rate Measurement Using Diffusion-Controlled Mass Transport
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Solution Overview
Problem
Conventional methods for determining the permeation rate of ultrabarrier materials lack sufficient sensitivity, particularly for low permeate concentrations, leading to inaccuracies and inability to detect very low permeation rates effectively.
Innovation Solution
The device employs a diffusion-controlled mass transport system where a permeate from a test gas space diffuses through a barrier element into a measuring chamber with a hollow guide element and a permeate sink, creating a concentration gradient, allowing for the calculation of permeation rate using Fick's first law, with an optical sensor for non-invasive measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional measurement methods (gas detection with non-dispersive infrared sensors or coulometric moisture sensors) are used, then the measurement system is simple and easy to operate, but the measurement sensitivity is insufficient to detect very low permeation rates in the range of 10^-6 g[H2O] m^-2 d^-1
Solution Approach 1:
The patent introduces an intermediary substance (permeate sink material such as calcium chloride or silica gel) that mediates between the barrier element and the measurement system. This intermediary absorbs and concentrates the permeate in a controlled manner, enabling detection of very low permeation rates while maintaining system simplicity
Solution Approach 2:
The patent changes the measurement parameter from direct permeate detection to detection of the permeate sink's absorption state. By monitoring changes in the permeate sink (mass increase, moisture content), the system achieves high sensitivity for ultra-barrier materials without requiring complex detection equipment
2Measurement precision
If isostatic measurement methods with laser-based detection systems are used, then the measurement sensitivity is improved, but the detection limit remains insufficient for ultra-barrier materials and very small carrier gas flows of 3 sccm require excessively long adjustment times to equilibrium state
Solution Approach 1:
The patent applies preliminary action by pre-placing the permeate sink in position and pre-establishing the concentration gradient before the measurement begins. The permeate sink is pre-conditioned and positioned to immediately absorb permeate as it passes through the barrier element, eliminating the need for long equilibrium adjustment periods
Solution Approach 2:
The patent implements periodic action through continuous replacement or regeneration of the permeate sink. By periodically refreshing the permeate sink, the system maintains a constant concentration gradient and avoids equilibrium saturation, enabling continuous measurement without long adjustment times
3Measurement precision
If carrier gas flows are reduced to very small values of 3 sccm to improve measurement sensitivity, then the detection limit is improved, but the adjustment time to equilibrium state becomes excessively long and uncertainties in permeate mass flow determination increase significantly
Solution Approach 1:
The permeate sink acts as an intermediary that decouples the measurement from the carrier gas flow rate. By absorbing permeate directly from the gas phase, the system achieves flow-independent measurement, eliminating the trade-off between flow rate and measurement sensitivity
Solution Approach 2:
The patent replaces the mechanical carrier gas flow system with a passive diffusion-absorption system. Instead of relying on gas flow to transport permeate to the detector, the system uses concentration gradient-driven diffusion to the permeate sink, eliminating flow rate uncertainties
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
This approach enables precise determination of permeation rates down to 10^-6 g[H2O] m^-2 d^-1, improving measurement sensitivity and accuracy by maintaining a constant permeate concentration and concentration gradient, thus overcoming the limitations of existing methods.
Implementation Method 1
a permeate in an inert gas atmosphere along a diffusion path of a known length, diffuses without flow to a permeate sink
Implementation Method 2
radiation with at least one absorption wavelength of a respective permeate... is transmitted through the measuring chamber and/or through at least one hollow guide element... and onto at least one optical detector which is suitable for determining an intensity of at least one respective absorption wavelength of the permeate
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 3a~3b
AI summary
The invention relates to a device and a method for determining the permeation rate of barrier and ultrabarrier elements using an isostatic permeation measurement method. In this method, the convective mass transport of permeate passing through a barrier element in a downstream measuring chamber with a hollow guide element and permeate sink is replaced by diffusion-controlled mass transport along a diffusion path. The permeate sink ensures that permeate is continuously removed, so that a mass flow equilibrium of the permeate is established through the barrier element and the diffusion path. By non-invasively determining the concentration of the permeate along the diffusion path, the concentration gradient of the permeate and, from this, the permeation rate of the barrier element are determined.