Porous Solid Permeability Measurement with Dynamic Pressure Ramping
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Solution Overview
Problem
Conventional capillary flow porometry methods face challenges in achieving high-resolution pore size determination of porous materials without compromising test time, particularly when dealing with complex structures having varying tortuosity and pore lengths.
Innovation Solution
A dynamic pressure ramping method that adjusts pressure ramp rate based on gas flow changes, using exponential control to maximize resolution, allowing for rapid and precise measurement of pore size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pressure ramping is used to reduce test time, then productivity is improved, but measurement precision deteriorates due to insufficient time for gas flow to displace wetting liquid in tortuous pores
Solution Approach 1:
The pressure ramp rate is made dynamic rather than constant. The system continuously adjusts the pressure ramp rate based on real-time feedback from gas flow measurements. When gas flow increases indicate pore opening, the ramp rate automatically decreases to allow proper displacement of wetting liquid, ensuring accurate pore size determination while maintaining overall test efficiency.
Solution Approach 2:
The system implements feedback control by monitoring gas flow changes and using this information to adjust the pressure ramp rate. The gas flow signal serves as feedback that triggers ramp rate modification, creating a closed-loop control system that adapts to the sample's pore structure characteristics in real-time.
2Measurement precision
If pressure stepping with stabilization periods is used to improve measurement precision, then measurement precision is improved, but productivity deteriorates due to extended test time
Solution Approach 1:
Instead of using fixed, predetermined stabilization periods, the system dynamically determines when stabilization is sufficient based on gas flow measurements. The pressure ramp rate adjusts automatically in response to gas flow changes, providing just enough stabilization time for accurate measurement without unnecessary delays.
Solution Approach 2:
The system changes the pressure application parameter dynamically based on measured gas flow. Rather than maintaining constant pressure steps with fixed durations, the pressure ramp rate parameter is continuously modified according to the observed gas flow response, optimizing both precision and speed.
3Productivity
If large pressure step sizes are used to reduce test time, then productivity is improved, but measurement precision deteriorates due to reduced resolution in pore size distribution
Solution Approach 1:
The pressure ramp rate is dynamically adjusted to be slower when gas flow changes indicate pore opening events, and faster when no significant flow changes occur. This dynamic adaptation allows the system to capture detailed pore size distribution information without requiring uniformly small pressure steps throughout the entire pressure range.
Solution Approach 2:
The system applies pressure ramping at varying rates, using slower ramp rates only when and where needed (during pore opening events detected by gas flow changes) to maintain resolution, while using faster ramp rates during portions of the pressure range where high resolution is not critical, thus optimizing overall test time.
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 significantly reduces test time while enhancing measurement resolution, accurately determining pore sizes across a range of pore diameters with minimal error.
Implementation Method 1
pores are opened as wetting fluid is forced through the sample. Pores with larger effective diameters are opened at lower pressures than pore with smaller effective diameters.
Implementation Method 2
pressure increases, pores are opened as wetting fluid is forced through the sample
Implementation Method 3
a sample is fully wetted using a fluid with a known surface tension and pressure is applied via pressure ramping or pressure stepping to the sample to identify the first bubble point
Data Source
AI summary
A method and apparatus for dynamically adjusting pressure ramping to maximize determination of capillary porosity resolution of a porous material. The method dynamically increases pressure ramp rate applied to a wetted sample as rate of mass flow change decreases and dynamically decreases pressure ramp rate as rate of mass flow change increases. The method can further control the pressure ramp sensitivity to changes in mass flow rate and can apply a resolution parameter to control the rate of pressure change.