Cryogenic Hydrogen Pump Leak-By Control for Reduced Vaporization
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Solution Overview
Problem
Existing hydrogen fueling stations face issues with vaporization and instability due to mechanical coupling of pumps, leading to inefficiency and uneven wear on seals, particularly when transitioning liquid hydrogen to a gaseous state.
Innovation Solution
A cryogenic pump system with thermal decoupling rods and blow-by seals that allow controlled leakage of hydrogen, reducing mechanical coupling and stabilizing the system, while using variable volume working chambers and relief valves to manage pressure differentials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a single drive rod mechanically couples both pumping stages, then energy transfer to liquid hydrogen is minimized, but the first stage pump operates at mass flow rates exceeding the second stage pump capacity causing system inefficiency
Solution Approach 1:
The patent divides the single mechanically coupled drive system into two independently controlled pumping stages. Each stage has its own drive mechanism, allowing independent optimization of mass flow rates and pressure increases for each stage, eliminating the inefficiency where the first stage operates beyond the second stage's capacity.
2Object-affected harmful factors
If liquid hydrogen is gravity fed into the first stage pump suction, then vaporization is minimized during transport, but the pump cannot handle vaporized hydrogen effectively and becomes top-heavy when oriented vertically
Solution Approach 1:
The patent inverts the traditional vertical orientation by positioning the pump horizontally with the drive shaft at the bottom. This allows the pump to effectively handle vaporized hydrogen while maintaining stability, as the horizontal orientation prevents vapor accumulation at the suction inlet and distributes weight evenly on the ground support.
3Object-affected harmful factors
If the pump is oriented vertically with the drive shaft at the top, then vaporized hydrogen migration to upper areas is prevented, but the pump becomes top-heavy and inherently unstable
Solution Approach 1:
The patent inverts the vertical orientation to a horizontal configuration with the drive shaft positioned at the bottom. This inversion maintains stability by distributing the pump's weight evenly on ground support while still preventing vaporized hydrogen migration to the suction inlet through proper internal flow path design.
4Ease of operation
If a valve creates pressure drop to control hydrogen flow, then flow rate is regulated, but the pressure drop causes flash vaporization of liquid hydrogen
Solution Approach 1:
The patent introduces a节流装置 (flow control device) as an intermediary between the storage tank and pump suction. This device gradually reduces pressure through a controlled flow path rather than creating a sudden pressure drop, allowing flow rate regulation while preventing flash vaporization of liquid hydrogen.
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 system effectively reduces vaporization and enhances stability, allowing efficient operation with extended stroke lengths and reduced component wear, improving the efficiency and reliability of hydrogen fueling stations.
Implementation Method 1
The first blow by seal is configured to provide leakage of hydrogen from the first area past the first blow by seal into the first thermal decoupling cylinder when a second hydrogen pressure is present in the first area. The first hydrogen pressure is greater than the second hydrogen pressure.
Implementation Method 2
The at least one relief valve is configured to provide leakage of hydrogen from the first thermal decoupling cylinder to maintain a third hydrogen pressure within the first thermal decoupling cylinder.
Implementation Method 3
A first coupler couples a first end portion of the first hydrogen pump cylinder to a first end portion of a first thermal decoupling cylinder. The first blow by seal is mounted to the first coupler and is in sliding sealing engagement with the first hydrogen piston.
Implementation Method 4
The first blow by seal is mounted to the first coupler and is in sliding sealing engagement with the first hydrogen piston.
Data Source
AI summary
A hydrogen fueling station includes a cryogenic pump with a hydrogen piston at least partially positioned within a hydrogen pump cylinder. A variable volume working chamber is defined at least in part by the hydrogen piston, a seal extending around the piston, and an end portion of the hydrogen pump cylinder opposite the first end portion of the first hydrogen pump cylinder. The hydrogen pump cylinder is coupled with a coupler to a thermal decoupling cylinder. The seal provides hydrogen leakage at a first pressure in the variable volume working chamber to an area beneath the seal. A blow by seal mounted to the first coupler provides hydrogen leakage to the thermal decoupling cylinder. A relief valve provides hydrogen leakage out of the thermal decoupling cylinder. The first hydrogen pressure is greater than the second hydrogen pressure, and the second hydrogen pressure is greater than the third hydrogen pressure.