Liquid Hydrogen Storage Tank Fill Level Indicator

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Solution Overview

Problem

Existing technologies face challenges in reliably detecting the fill level of liquid hydrogen in storage tanks due to the complex physical properties of hydrogen, requiring measurement of multiple physical quantities and complex calculations.

Innovation Solution

A storage tank system with an inner and outer tank configuration, incorporating a cell filled with a gas that liquefies when submerged in liquid hydrogen, a pressure indicator device to detect the pressure drop upon liquefaction, and a heating element to maintain the gas in a gaseous state until the fill level is reached.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a fill level indicator is realized with the differential pressure method or capacitive measurement, then the fill level can be detected, but the measurement requires complex calculations and multiple physical quantities due to the physical properties of hydrogen

Engineering Contradiction:

Improvefill level detectionVSAvoidmeasurement complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses a gas that undergoes phase transition from gaseous to liquid state when the cell is dipped into liquid hydrogen. This phase transition causes a detectable pressure drop in the cell, providing a simple and reliable fill level indication without requiring complex measurements or calculations. The phase transition of the gas serves as a direct indicator that the fill level has been reached.

Inventive Principle:

Principle #36Phase transitions

2Device complexity

If no heating device is provided, then the device structure is simpler, but the gas may liquefy before the liquid hydrogen reaches the cell or the gas may not vaporize reliably in closed insulated tanks

Engineering Contradiction:

Improvedevice structureVSAvoidfill level indication reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The heating element continuously introduces heat into the gas before the liquid hydrogen reaches the cell, ensuring the gas remains in gaseous state and is ready for reliable phase transition detection. This preliminary heating action prevents premature liquefaction and ensures the gas can be reliably vaporized when needed, maintaining measurement reliability in closed insulated tanks.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The heating element changes the temperature parameter of the gas, maintaining it above the liquefaction point until the fill level is reached. This parameter control ensures the gas remains in the appropriate state for detection and can undergo reliable phase transition when the liquid hydrogen contacts the cell.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If external heat input is used to vaporize the gas, then the gas can be reliably vaporized, but this requires constant external energy input and creates a cold leak

Engineering Contradiction:

Improvegas vaporization reliabilityVSAvoidexternal heat input

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The heating element is integrated within the cell structure, allowing the cell to self-regulate the gas temperature. The system uses internal heating rather than external heat input, eliminating the cold leak issue while maintaining reliable gas vaporization. The cell serves itself by containing the heating element that directly heats the gas as needed.

Inventive Principle:

Principle #25Self-service

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 solution allows for a reliable and simplified indication of the predefined fill level in liquid hydrogen storage tanks, even in closed and highly insulated tanks, by utilizing the phase transition of the gas to indicate fill level reached and ensuring accurate measurement without external heat input.

Implementation Method 1

a heating element (31) which continuously introduces heat into the gas

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

a cell (25) which is arranged inside the inner tank (9) and is filled with a gas that liquefies when the cell is dipped into the liquid hydrogen

Methodology Applied

Scientific EffectPhase change (liquefaction): Phase Change

Implementation Method 3

liquefying a gas accommodated in the cell with the help of the liquid hydrogen

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 4

a pressure indicator device (30) which indicates a pressure drop in the cell (25) in the case of liquefaction of the gas and therefore indicates the predefined fill level has been reached

Methodology Applied

Scientific EffectPressure detection:

Data Source

PatentUS12320472B2Storage tank for liquid hydrogen with fill level indicator

Publication Date: 2025.06.03 LINDE AG

AI summary

A storage tank for liquid hydrogen having an outer tank, an inner tank which is arranged inside the outer tank, and a device for indicating a predefined fill level has been reached with a cell which can be arranged inside the inner tank and is filled with a gas which liquefies when the cell is dipped into the liquid hydrogen, further having a pressure indicator device which indicates a pressure drop in the cell in the case of liquefaction of the gas and therefore indicates the predefined filling level has been reached, and further having a heating element which continuously introduces heat into the gas.