Calibration Device Buoyancy Error Compensation
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Solution Overview
Problem
Calibration devices for hydrogen gas filling apparatuses face errors due to changing buoyant forces caused by temperature variations, especially when filling high-pressure hydrogen gas at low temperatures, which affects the accuracy of measuring the filled hydrogen quantity.
Innovation Solution
A calibration device with a measurement housing, a filling vessel, and a scale, along with a control device that calculates and compensates for buoyant forces from gases like dried air and nitrogen, using the gas temperature on the filling vessel's surface as a representative value to determine gas density and eliminate errors from buoyant force variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If hydrogen gas is filled at high pressure to shorten filling time, then productivity is improved, but temperature of the gas increases causing measurement errors due to changing buoyant force
Solution Approach 1:
The patent applies parameter changes by actively controlling the temperature of the hydrogen gas during filling. A temperature control unit cools the gas to maintain it at a predetermined temperature (e.g., 20°C) regardless of the filling pressure or speed. This temperature stabilization compensates for the buoyant force variations, allowing high-pressure fast filling while maintaining measurement accuracy.
2Reliability
If hydrogen gas is cooled at −40° C. to prevent fuel tank breakage, then reliability is improved, but temperature variation causes changing buoyant force and measurement errors
Solution Approach 1:
The patent resolves this contradiction by decoupling the cooling function into two separate stages: (1) Pre-cooling the hydrogen gas to −40°C or lower before filling to ensure fuel tank safety, and (2) Post-cooling or in-situ temperature control during filling to maintain the gas at a predetermined temperature for accurate measurement. The temperature control unit actively adjusts the temperature during the filling process, ensuring both safety and measurement accuracy are achieved simultaneously.
3Measurement precision
If the calibration device measures weight of filled hydrogen, then measurement capability is provided, but changing buoyant force from ambient gas causes errors in measured amount
Solution Approach 1:
The patent implements feedback control through a temperature control unit that continuously monitors the gas temperature during filling and actively adjusts it to maintain a predetermined temperature. This closed-loop temperature control compensates for buoyant force variations in real-time, ensuring that weight measurements accurately reflect the true mass of hydrogen filled, regardless of ambient temperature changes or filling speed variations.
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 ensures accurate measurement of hydrogen gas quantity by canceling out buoyant forces acting on equipment capacities, improving the calibration accuracy and reliability of hydrogen gas filling apparatuses, even when filling hydrogen cooled to −40° C.
Implementation Method 1
a scale 3 for measuring a weight of a fuel gas fed to the filling vessel 2
Implementation Method 2
a control device CU for eliminating an error caused by changing buoyant force from a gas in the measurement housing before and after filling the fuel gas
Data Source
AI summary
To provide a calibration device for apparatus filling a gas such as hydrogen gas and capable of precisely measuring quantity of the gas that is filled at high pressure. A calibration device of the present invention includes: a filling vessel 2, accommodated in a measurement housing 1, to the filling vessel 2 a high pressure fuel gas such as hydrogen gas being fed from outside of the measurement housing 1; a scale 3 for measuring a weight of a fuel gas fed to the filling vessel 2; and a control device CU for eliminating an error caused by changing buoyant force from a gas in the measurement housing before and after filling the fuel gas.