Two-Stage Liquid Hydrogen Pumping for Cavitation and Leak Control
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Solution Overview
Problem
Existing technologies for pumping liquid hydrogen face challenges such as high energy and investment costs, complex operation at high pressures, cavitation phenomena, and significant losses due to vaporization and leaks, which affect pump performance and maintenance complexity.
Innovation Solution
A two-stage compression system where the first stage compresses liquid hydrogen to a supercritical state, followed by a second stage that further compresses the supercritical hydrogen to high pressures, utilizing independent piston movements and thermal isolation to manage thermodynamic conditions and minimize leaks and cavitation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If liquid hydrogen is compressed directly at high pressure, then compression energy is reduced compared to compressing gaseous hydrogen, but cavitation phenomena occur due to vaporization from thermal inputs and compression heat
Solution Approach 1:
The compression process is divided into two distinct stages: a first compression stage that operates at lower pressure to avoid cavitation, and a second compression stage that achieves the final high pressure. This segmentation allows each stage to operate within optimal parameters, preventing vaporization-related cavitation while maintaining energy efficiency.
Solution Approach 2:
The first compression stage performs preliminary compression of liquid hydrogen before the second stage. By pre-compressing the liquid hydrogen to a moderate pressure level, the system prepares the fluid for the subsequent high-pressure compression without causing excessive heat generation that would lead to cavitation in the final stage.
2Productivity
If pump operates at high pressure, then compression efficiency is improved, but leaks through piston sealing segments increase and are difficult to recover
Solution Approach 1:
The compression system is divided into two stages with different pressure levels. The first stage operates at lower pressure where sealing is more effective, minimizing leaks. The second stage operates at high pressure but processes a smaller volume of already pre-compressed gas, reducing the absolute amount of potential leaks while maintaining high compression efficiency.
Solution Approach 2:
The first compression stage acts as an intermediary that prepares the liquid hydrogen by removing a portion of it and compressing it to an intermediate pressure state. This intermediary step reduces the workload and leak potential for the second high-pressure stage, as it handles a reduced volume of fluid.
3Productivity
If two-stage compression is implemented, then compression performance is improved, but device complexity increases
Solution Approach 1:
The first compression component is designed to serve multiple functions: it acts as a primary compressor for liquid hydrogen, functions as a heat shield for the second compression stage through thermal conduction, and provides structural support. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in device complexity despite the two-stage configuration.
Solution Approach 2:
The first compression component merges the functions of compression and thermal shielding into a single integrated structure. The housing of the first compressor serves as the heat shield for the second stage, eliminating the need for a separate heat shield component and reducing overall system complexity.
4Reliability
If pump is immersed in liquid hydrogen container, then thermalization is optimized and cavitation is limited, but maintenance complexity increases
Solution Approach 1:
The second compression stage, which operates in the high-pressure gaseous hydrogen environment, is extracted as a separate, remotely accessible component. This allows the second stage to be maintained independently without requiring drainage and maintenance of the entire pump system immersed in liquid hydrogen, significantly reducing maintenance complexity while preserving the thermalization benefits.
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 compresses liquid hydrogen to high pressures with reduced energy consumption, minimized vaporization losses, and extended pump life by controlling thermodynamic conditions and sealing faults, ensuring stable operation and reduced maintenance needs.
Implementation Method 1
the first compression component is suitable for and is configured for compressing the liquid hydrogen in a supercritical state
Implementation Method 2
the second compression component is suitable for and is configured for compressing the supercritical hydrogen supplied by the first compression component at a high pressure
Implementation Method 3
the first compression component comprises at least one assembly comprising a piston that is translationally movable in a sleeve, with the second compression component comprising at least one assembly comprising a separate piston arranged in a separate sleeve
Data Source
AI summary
Device for pumping liquid hydrogen including, arranged in series between an inlet for fluid to be compressed and an outlet for compressed fluid, a first compression member with a piston forming a first compression stage and a second compression member with a piston forming a second compression stage. The first compression member compresses the liquid hydrogen to a supercritical state. The second compression member compresses the supercritical hydrogen from the first compression member to an increased pressure, in particular, between 200 and 1000 bar.