Long-Stroke Cryogenic Pump for Stable Liquid Hydrogen Transfer
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Solution Overview
Problem
Existing hydrogen fueling stations face issues with vaporization and stability due to the physical constraints of liquid hydrogen, inefficient energy transfer, and unequal pressure on pump seals, leading to inefficiency and instability.
Innovation Solution
A hydrogen fueling station design featuring a hydrogen pump cylinder with a hydrogen piston and thermal decoupling rod, allowing for a stroke length of over 310 mm, and a mechanical stop at the roof, along with a hydraulic system that decouples mechanical forces, stabilizes the pump, and minimizes thermal conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a single drive rod is used to drive both first stage and second stage pumps, then energy transfer to liquid hydrogen is minimized, but the first stage pump operates at a mass flow rate exceeding the capacity of the second stage pump, resulting in system inefficiency
Solution Approach 1:
The patent divides the pumping system into two independently driven stages. The first stage pump is driven by a first drive rod and the second stage pump is driven by a second drive rod, allowing each stage to operate at its optimal mass flow rate without the constraints of a coupled mechanical system. This segmentation resolves the contradiction by enabling energy efficiency in thermal isolation while maintaining productivity through independent optimization of each pumping stage's operating parameters
2Quantity of substance
If bulk liquid hydrogen is kept close to its triple point to reduce storage costs, then storage efficiency is improved, but the liquid hydrogen is easily vaporized with only a slight increase in temperature or reduction of pressure, making pumping problematic
Solution Approach 1:
The patent incorporates a valve between the bulk storage tank and the first stage pump that is pre-configured to create a controlled pressure drop. This preliminary action ensures that liquid hydrogen entering the pump is maintained at a pressure sufficient to prevent vaporization during the pumping process, while still allowing the bulk storage to operate at economical conditions near the triple point. The valve is designed to provide the necessary pressure boost without requiring additional heating or cooling infrastructure
3Reliability
If the pump is oriented vertically with the motor and drive shaft at the upper side, then vaporized hydrogen migration to upper areas is prevented, but the pump becomes top-heavy and inherently unstable
Solution Approach 1:
The patent employs a counterweight mechanism attached to the pump assembly that offsets the top-heavy condition created by the vertical orientation with the motor and drive shaft positioned at the upper side. The counterweight is strategically positioned to balance the center of gravity, thereby preventing the pump from being inherently unstable while maintaining the vertical orientation that prevents vaporized hydrogen migration to upper areas. This allows the system to simultaneously achieve both vaporization prevention and mechanical stability
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 design reduces vaporization and enhances stability, enabling efficient hydrogen transfer and operation even from a warm start, with improved energy efficiency and simplified component layout.
Implementation Method 1
a hydrogen piston and a thermal decoupling rod, wherein the thermal decoupling rod minimizes thermal conductivity into the liquid hydrogen
Implementation Method 2
The hydrogen piston is configured to provide a stroke length of greater than 310 mm... The transition from liquid to gaseous hydrogen in some systems effected with the aid of a dual stage pumping system. In a first stage the liquid hydrogen is 'supercooled' by increasing the pressure of the fluid with a first stage pump. The temperature of the supercooled hydrogen is increased from the initial temperature due to the working of the first stage pump.
Implementation Method 3
along with a hydraulic system that decouples mechanical forces, stabilizes the pump, and minimizes thermal conductivity
Data Source
AI summary
A hydrogen fueling station includes a hydrogen supply header, a hydrogen pump cylinder, and a hydrogen piston, the hydrogen piston including a piston seal. The hydrogen pump cylinder is configured to receive hydrogen from the hydrogen supply header. The hydrogen piston, the piston seal, and the hydrogen pump cylinder define at least in part a variable working chamber. The hydrogen piston is configured to provide a stroke length of greater than 310 mm.