Cryogenic Pump Hydraulic Control for Hydrogen Vaporization Prevention
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Solution Overview
Problem
Existing hydrogen fueling stations face issues with vaporization of liquid hydrogen due to temperature increases and mechanical inefficiencies in dual-stage pumping systems, leading to instability and uneven wear on pump seals.
Innovation Solution
A cryogenic pump hydraulic system with independently controlled hydraulic pistons and controllable valves to manage pressure and position, reducing energy transfer and stabilizing the pump by positioning hydraulic components at the bottom for stability and using thermal decoupling to minimize heat transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a dual-stage pumping system is used to pressurize liquid hydrogen, then the hydrogen can be delivered to vehicles, but the liquid hydrogen vaporizes due to temperature increase and pressure drop
Solution Approach 1:
The system pre-cools the liquid hydrogen to a temperature below the triple point before it enters the pump suction. This preliminary cooling action prevents vaporization that would occur if the hydrogen were at ambient or bulk storage temperature, allowing the pump to operate reliably without losing liquid phase stability
Solution Approach 2:
The invention changes the temperature parameter of the liquid hydrogen by pre-cooling it to sub-triple-point temperatures. This parameter change shifts the phase boundary, allowing the hydrogen to remain liquid through the pressure drop in the pump suction that would otherwise cause vaporization
2Loss of energy
If a single drive rod is used to drive both pumps, then energy transfer is reduced, but the first stage pump operates at mass flow rate exceeding the second stage pump capacity
Solution Approach 1:
The invention segments the drive mechanism into independent drive rods for the first and second stage pumps. This allows each pump to be independently controlled and operated at its optimal mass flow rate, preventing the inefficiency where the first stage pump operates at excessive flow rates that the second stage pump cannot handle
Solution Approach 2:
The system dynamically controls the mass flow rate through each pump stage independently, allowing the first stage pump to operate at higher flow rates when needed while the second stage pump operates at its appropriate capacity. This dynamic adjustment eliminates the mismatch problem inherent in single-drive-rod systems
3Device complexity
If hydraulic components are positioned at the top of the pump, then the pump structure is simplified, but the pump becomes top-heavy and unstable
Solution Approach 1:
The invention positions the heavy hydraulic components and motor assembly at the bottom of the pump housing, creating a low center of gravity that counteracts any top-heavy tendencies and provides inherent stability. This weight distribution arrangement prevents excessive vibration and ensures stable operation during pump cycles
4Device complexity
If the pump operates without thermal decoupling, then the structure is simpler, but heat transfer causes vaporization and seal wear
Solution Approach 1:
The invention introduces thermal decoupling elements as intermediaries between the cold liquid hydrogen and the warmer pump components. These thermal barriers minimize heat transfer from the pump structure to the liquid hydrogen, preventing vaporization and reducing thermal stress on seals and other components
Solution Approach 2:
The system replaces direct thermal contact with thermal decoupling mechanisms that use materials or structures with low thermal conductivity. This substitution reduces heat transfer pathways without requiring complex active cooling systems, maintaining simplicity while improving reliability
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 prevents vaporization and stabilizes the pump, enhancing efficiency by minimizing energy loss and reducing wear on seals, thus improving the reliability and stability of hydrogen fueling operations.
Implementation Method 1
A cryogenic pump hydraulic system with independently controlled hydraulic pistons and controllable valves to manage pressure and position
Implementation Method 2
using thermal decoupling to minimize heat transfer
Data Source
AI summary
A hydrogen fueling station includes a cryogenic pump hydraulic system with two hydraulic cylinders including hydraulic pistons with piston seals separating low pressure portions of the hydraulic cylinders above the piston seals from high pressure portions of the hydraulic cylinders beneath the piston seals. At least one first hydraulic volume source is configured to selectively communicate fluid between the first high pressure portion and the second high pressure portion. A first controllable valve is configured to selectively place the first and second low pressure portion in fluid communication with at least one low-pressure line. A second controllable valve is configured to selectively place at least one second hydraulic volume source in fluid communication with the first high pressure portion. A third controllable valve is configured to selectively place the at least one second hydraulic volume source in fluid communication with the second high pressure portion.