Segmented Ceramic Void Fraction Sensing 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 enhances measurement accuracy by maintaining insulation and positioning precision.
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 likely to generate and extend due to thermal shock from cryogenic liquid hydrogen
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 adjacent to each other with electrodes on their outer surfaces, allowing the structure to accommodate thermal expansion and contraction independently, thereby preventing crack generation and extension due to thermal shock from cryogenic liquid hydrogen.
2Device complexity
If liquid hydrogen flow rate is measured by only measuring flow velocity, then the measurement method is simple, but the measurement is inaccurate due to large fluctuation of gas-to-liquid ratio
Solution Approach 1:
A capacitance type void fraction sensor is introduced as an intermediary measurement device to measure the void fraction (gas phase volume percentage) of the gas-liquid two-phase flow. This sensor uses electrodes on ceramic members to detect the capacitance of the flowing liquid hydrogen, providing accurate void fraction data that, when combined with flow velocity measurements, enables precise flow rate determination despite large fluctuations in gas-to-liquid ratio.
3Ease of manufacture
If electrodes are attached from the outside to an integrally formed pipe, then the manufacturing process is simple, but the pipe is susceptible to thermal shock and crack generation
Solution Approach 1:
The pipe structure is segmented into multiple separate ceramic members with electrodes attached to their outer surfaces. This segmentation allows each member to independently respond to thermal changes, reducing thermal shock susceptibility and preventing crack generation while maintaining the ease of electrode attachment from the outside.
4Measurement precision
If a capacitance type void fraction sensor is used to measure void fraction, then the measurement capability is improved, but the sensor structure becomes more complex with multiple ceramic members
Solution Approach 1:
The sensor structure uses segmented ceramic members that are adjacent to each other, with electrodes on their outer surfaces. This segmentation provides measurement capabilities across different positions while maintaining a relatively simple overall structure through the use of identical modular ceramic member units.
Solution Approach 2:
Each ceramic member serves multiple functions: it provides structural support, electrical insulation, and a mounting surface for electrodes. The segmented design allows the same ceramic member structure to be replicated and arranged in different configurations for various measurement requirements, enhancing versatility without increasing the complexity of individual components.
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 sensor provides accurate measurement of void fraction and flow rate of liquid hydrogen, ensuring reliable and durable operation even in cryogenic conditions, facilitating efficient 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
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.