Liquid Hydrogen Transfer With Pump Subcooling and Single-Line Filling
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Solution Overview
Problem
Existing methods for transferring liquid hydrogen face challenges in achieving high filling rates and efficient pressure management in large storage containers, leading to hydrogen losses and complex infrastructure requirements.
Innovation Solution
A centrifugal pump with at least 30% efficiency is used to subcool liquid hydrogen, combined with a single connecting line and pressure control system to maintain the receiver pressure below its maximum, terminating the process when the pressure reaches a predetermined limit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a piston pump or centrifugal pump is used to generate pressure differential for liquid transfer, then the transfer pressure can be controlled, but the pump inlet may not achieve sufficient NPSHA leading to cavitation
Solution Approach 1:
The patent changes the temperature parameter of the liquid hydrogen to achieve subcooling. By lowering the temperature below the normal boiling point, the vapor pressure is reduced, which increases the NPSHA available at the pump inlet, preventing cavitation while allowing the pump to generate the required pressure differential for transfer.
Solution Approach 2:
The patent utilizes the phase transition properties of hydrogen by subcooling the liquid hydrogen. This creates a liquid state at temperatures below the normal boiling point, which fundamentally changes the thermodynamic properties and reduces vapor pressure, thereby preventing cavitation at the pump inlet.
2Stress or pressure
If liquid hydrogen is conditioned using a pressure regulating system with ambient vaporizer, then the pressure in the dispenser can be regulated, but the system complexity increases
Solution Approach 1:
The patent extracts the pressure regulation function from a separate complex system and integrates it into the pump operation itself. The centrifugal pump's inherent pressure generation capability is used to achieve both subcooling and pressure regulation, eliminating the need for separate pressure regulating valves and ambient vaporizers.
Solution Approach 2:
The centrifugal pump is given multiple functions: it not only transfers the liquid hydrogen but also subcools it and regulates the pressure. This multi-functionality eliminates the need for separate pressure regulation equipment, simplifying the overall system while achieving the required pressure control.
3Device complexity
If a single connecting line is used between donor and receiver, then the infrastructure complexity is reduced, but the filling rate is limited to less than 100 kg
Solution Approach 1:
The patent changes the temperature and pressure parameters of the liquid hydrogen through subcooling, which increases the density and reduces vapor pressure. This allows the single connecting line to handle higher flow rates up to 1 tonne per hour without exceeding the receiver's pressure limits, as the subcooled liquid expands less upon entering the receiver.
Solution Approach 2:
The patent implements pressure monitoring in the receiver with automatic control that terminates the filling process when the maximum permissible pressure is reached. This feedback mechanism allows the system to safely operate at higher filling rates through a single line by automatically stopping before pressure limits are exceeded.
4Loss of substance
If the receiver pressure is maintained below maximum during filling, then hydrogen losses are reduced, but the filling process must be terminated early
Solution Approach 1:
The patent subcools the liquid hydrogen before transfer, which increases its density and reduces its volume for the same mass. This allows the receiver to accept more hydrogen mass before reaching the maximum pressure limit, effectively extending the filling duration and reducing losses without requiring early termination.
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
Enables rapid filling of large storage containers with over 200 kg at rates exceeding 1 tonne per hour, reducing infrastructure complexity and hydrogen losses by condensing excess gas back into liquid form.
Implementation Method 1
the centrifugal pump is designed in such a way that it allows subcooling of the liquid hydrogen at the pump outlet
Implementation Method 2
reducing infrastructure complexity and hydrogen losses by condensing excess gas back into liquid form
Data Source
Figure 1
AI summary
An arrangement for transferring liquid hydrogen from a first storage container (1) to a second storage container (2) is described, in which the storage container to be filled can be filled with a filling quantity of more than 200 kg at filling rates of more than 1 tonne per hour, for which only a filling line but no return line is required.