Inverted Wick Cryogenic Temperature Control
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Solution Overview
Problem
Existing temperature control methods for adsorption analyzers, such as those using cryogenic fluids, face challenges in maintaining constant volumes and temperatures due to evaporation, leading to errors in adsorption measurements, with existing solutions either requiring complex hardware or increasing the volume at cryogenic temperature, thus affecting measurement accuracy.
Innovation Solution
An apparatus with an inverted wick that surrounds the sample vessel, allowing the cooling liquid to be drawn down through capillary action, maintaining a constant temperature and minimizing the volume at cryogenic temperature, thereby enhancing measurement sensitivity and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a wick is used to maintain constant cryogenic volume, then the cold volume is kept constant, but the fraction of sample cell volume at cryogenic temperature increases
Solution Approach 1:
The patent inverts the conventional wick configuration by placing the wick at the bottom of the sample cell instead of above it. The wick extends upward from the bottom, drawing cryogenic liquid up through capillary action. This inversion allows the wick to maintain a constant meniscus level at the top of the sample cell while minimizing the overall cryogenic volume, as the cooling liquid is drawn only to the necessary level rather than flooding the entire cell.
Solution Approach 2:
The patent utilizes a porous wick material that provides capillary channels for the cryogenic liquid to travel through. The porous structure enables the liquid to be drawn upward against gravity through capillary pressure, maintaining a stable meniscus level at the top of the sample cell while using minimal amounts of cryogenic liquid, thus resolving the contradiction between constant volume and minimal cryogenic fraction.
2Volume of stationary object
If the dewar is moved up to maintain constant fluid level, then the sample cell immersion is minimized, but the temperature gradient in the warm volume changes with time
Solution Approach 1:
The inverted wick system is self-regulating and requires no external control mechanisms. The capillary action in the wick automatically maintains a constant meniscus level at the top of the sample cell, ensuring stable temperature conditions in the warm volume without requiring motorized adjustment or external intervention, thus eliminating the temperature gradient instability problem.
Solution Approach 2:
The wick acts as an intermediary between the cryogenic liquid reservoir and the sample cell, regulating the cryogenic liquid level through capillary action. This intermediary mechanism maintains a stable thermal environment in the warm volume by preventing direct contact between the cryogenic liquid and the sample cell walls, thereby eliminating time-dependent temperature gradient changes.
3Device complexity
If the cryogenic fluid level is not controlled, then hardware complexity is reduced, but the cold volume fraction becomes very large
Solution Approach 1:
The inverted wick configuration is self-regulating through capillary action, requiring no external level control hardware. The porous wick material automatically draws cryogenic liquid to a constant level at the top of the sample cell, maintaining an optimal cold volume fraction without mechanical actuators, sensors, or control systems.
Solution Approach 2:
The porous wick structure provides passive capillary control of the cryogenic liquid level. The capillary pressure in the porous material automatically regulates the liquid height, preventing both overflow and depletion, thus maintaining an optimal cold volume fraction without any active level control hardware.
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 maintains a constant temperature within the sample cell with minimal cryogenic volume, improving the accuracy of adsorption measurements by reducing temperature gradients and eliminating the need for additional hardware or correction mechanisms, thus enhancing the sensitivity of adsorption analyzers.
Implementation Method 1
A wick (4) is disposed on the sample vessel (3) and surrounds the sample holding region (SHR). The wick (4) extends from the sample holding region (SHR) to project toward a bottom of the container (2) and draw the cooling liquid (CL) over the sample holding region (SHR)
Data Source
AI summary
A sample vessel assembly to carry out a sorption analysis in a container provided with a cooling liquid. The sample vessel assembly includes a sample vessel configured to be suspended within the container. The sample vessel has a sample holding region at a sample end of the vessel to hold a sample to be analyzed. A wick is disposed on the sample vessel and surrounds the sample holding region. The wick extends from the sample holding region to project toward a bottom of the container and draw the cooling liquid over the sample holding region when the sample vessel is disposed in an analysis position in the container.