Superconducting Flat Probe for Cryogenic Level Sensing
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Solution Overview
Problem
Conventional level detectors for cryogenic liquids in motor vehicle containers, such as those carrying liquefied hydrogen, face challenges in accuracy due to the close state variables of liquid and gas phases, high construction costs, and exposure of electrical connections, making them unsuitable for mass production and varying container sizes.
Innovation Solution
A flat conductor probe with a superconducting material, embedded in a plastic sheath with strategically placed heating and voltage-measuring conductors, providing flexibility and rigidity, and integrated with a guide tube for enhanced accuracy and durability, allowing for remote connection points and minimal heat transfer to the liquid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rigid rod probe with superconducting layer is used, then level detection capability is achieved, but construction costs increase and electrical connections become exposed
Solution Approach 1:
The patent replaces the rigid mechanical rod structure with a flexible cable containing superconducting wires. This substitution eliminates the complex mechanical support structure and substrate while maintaining the superconducting layer's functionality. The cable can be easily routed and connected, reducing construction complexity and cost while preserving measurement precision through the superconducting transition detection.
Solution Approach 2:
The patent uses a composite cable structure containing multiple superconducting wires (e.g., Nb3Sn, NbTi, Pb) embedded in an insulating matrix. This composite design integrates the superconducting functionality with mechanical flexibility and electrical insulation in a single element, eliminating the need for separate mechanical support structures and reducing overall device complexity while maintaining measurement accuracy.
2Measurement precision
If heating element is added to prevent superconducting transition in vapor area, then measurement accuracy improves, but heat transfer to liquid increases causing evaporation
Solution Approach 1:
The patent applies heating locally only in the vapor area above the liquid level using heating elements positioned on the cable. The insulating matrix and the natural thermal gradient in the cryogenic environment limit heat transfer primarily to the vapor phase, preventing unwanted superconducting transitions in the vapor area while minimizing heat transfer to the liquid and reducing evaporation losses.
Solution Approach 2:
The insulating matrix surrounding the superconducting wires acts as a thermal intermediary. It allows controlled heating of the vapor area while preventing excessive heat transfer to the liquid. The matrix mediates between the heating elements and the cryogenic environment, enabling accurate level detection through superconducting transition detection without significant energy loss to evaporation.
3Ease of manufacture
If probe is made flexible for mass production, then manufacturing ease improves, but structural rigidity decreases
Solution Approach 1:
The patent employs a flexible cable structure with superconducting wires embedded in an insulating matrix, replacing rigid rod designs. This flexible construction enables easy routing through various container configurations and simplifies installation while maintaining sufficient mechanical strength for practical applications. The flexibility facilitates mass production through standardized cable manufacturing processes.
Solution Approach 2:
The composite cable structure combines flexible insulating matrix material with embedded superconducting wires, creating a probe that is both flexible for easy installation and mass production, yet maintains adequate structural integrity. The composite design allows the probe to adapt to different container shapes and sizes while preserving the mechanical strength needed for reliable operation in vehicle environments.
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 solution offers a cost-effective, mass-producible level detector that maintains accuracy across different container sizes and shapes, reduces heating-induced evaporation, and provides flexible installation, while ensuring reliable measurements despite vehicle inclinations and vibrations.
Implementation Method 1
the first conductor (23) consists of a superconducting material whose transition temperature is suitable for liquid hydrogen
Implementation Method 2
pairs of second conductors (24) which serve to supply heating current to the first conductor (23)
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Disclosed is a level detector for cryogenic liquids that are placed in a receptacle (1). Said level detector uses a probe comprising a superconductor. In order to create an insensitive and inexpensive level detector, the probe (11) is embodied as a flat conductor (20) which is composed of several conducturs that are guided parallel to one another in a plastic matrix (21). A first conductor (23) represents a superconductor while second conductors (24) are used for feeding heating current to the first conductor (23), and third conductors (25; 25, 26) are used for measuring the voltage. The conductors of one pair (24, 25, 26) are respectively connected to the probe at points (27, 28 and 29, 30) located at a distance from each other in the longitudinal direction of the probe. The probe is guided within a guide in the receptacle.