Segmented Ceramic Void Fraction Sensor for Cryogenic Hydrogen Flow
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Solution Overview
Problem
Existing methods fail to accurately measure the flow rate of liquid hydrogen due to its high volatility and fluctuating gas-to-liquid ratio, leading to inaccuracies in determining the flow rate in transfer pipes.
Innovation Solution
A void fraction sensor using dividable ceramic members with electrodes on the outer or inner surface of a pipe to measure capacitance, which suppresses crack generation and maintains insulation, allowing for accurate void fraction measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an integrally formed pipe is used for the capacitance type void fraction sensor, then the structure is simple, but cracks are generated in the pipe due to thermal stress from liquid hydrogen, causing electrical short circuit and sensor failure
Solution Approach 1:
The pipe is divided into multiple separate ceramic members (first ceramic member and second ceramic member) instead of using an integrally formed pipe. These segmented members are arranged adjacently to form the complete pipe structure, which reduces thermal stress concentration and prevents crack propagation that would occur in a monolithic structure under cryogenic conditions.
2Ease of manufacture
If a single ceramic member is used for the pipe, then manufacturing is simple, but the pipe cannot withstand thermal stress from liquid hydrogen without cracking
Solution Approach 1:
The pipe is constructed from multiple separate ceramic members rather than a single piece. This segmentation allows each member to independently withstand thermal stress without developing critical cracks, while the overall assembled structure maintains the required mechanical strength and thermal resistance for liquid hydrogen service.
3Reliability
If the pipe is made from multiple ceramic members, then thermal stress resistance is improved, but the assembly process becomes more complex
Solution Approach 1:
The pipe is divided into multiple ceramic members that can be manufactured separately and then assembled. This segmentation enables each component to be optimized for thermal stress resistance while the assembly process, though more complex than a single-piece construction, is manageable through standardized joining methods and maintains overall system reliability.
4Measurement precision
If capacitance electrodes are attached to the pipe, then void fraction measurement is enabled, but the pipe structure becomes more complex and vulnerable to failure
Solution Approach 1:
The capacitance electrodes are integrated with the ceramic pipe members themselves rather than being separate attachments. The electrodes are formed as part of the ceramic member structure, which simplifies the overall construction by combining the structural and measurement functions into a single integrated component, reducing the number of separate parts and potential failure points.
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 enables precise measurement of void fraction and flow rate of liquid hydrogen, enhancing durability and reliability for mass transportation.
Implementation Method 1
an electrode provided on an outer peripheral surface of the pipe to measure capacitance of the cryogenic liquid flowing in the conduit
Data Source
Figure 1
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Figure 3A
AI summary
A void fraction sensor for measuring a void fraction of a cryogenic liquid includes a pipe having a conduit in which the cryogenic liquid flows, and an electrode provided on the outer peripheral surface of the pipe to measure capacitance of the cryogenic liquid flowing in the conduit. The pipe is composed of an even number of dividable ceramic members, and among the even number of ceramic members, at least two ceramic members facing each other are each provided with the electrode.