Cryogenic Fluid Dispensing System Subcooling
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Solution Overview
Problem
Current hydrogen refueling systems face challenges in efficiently cooling and delivering gaseous hydrogen to fuel cell vehicles, with high equipment costs and inefficiencies in liquid hydrogen storage and pumping, leading to temperature fluctuations and product loss.
Innovation Solution
A cryogenic fluid dispensing system featuring a bulk tank with a sump and a single-stage positive displacement pump submerged in cryogenic liquid, where the pump generates subcooling by retaining heat within the sump, preventing it from being returned to the bulk tank and using it to maintain liquid hydrogen in a subcooled state for efficient delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a compressor is used to compress hydrogen gas to high pressure, then the hydrogen can be delivered to the vehicle, but the equipment cost increases significantly
Solution Approach 1:
The system changes the physical state parameter of hydrogen from gaseous to liquid, enabling storage and transport at much lower pressures. Liquid hydrogen is stored in a bulk tank at cryogenic temperatures, and a pump delivers the liquid to a vaporizer that converts it to gas for the vehicle, eliminating the need for expensive high-pressure compressors
Solution Approach 2:
The patent replaces the mechanical compression system (compressor) with a thermal field-based system using cryogenic liquid hydrogen storage and a pump. The liquid hydrogen is delivered at low pressure and vaporized on-demand, substituting mechanical compression with phase change and thermal energy management
2Quantity of substance
If liquid hydrogen is stored in a bulk tank, then storage capacity increases, but heat load on the tank increases requiring more venting
Solution Approach 1:
The patent introduces a sump as an intermediary thermal management zone between the bulk tank and the pump. The sump receives liquid hydrogen from the bulk tank and uses a heat exchanger to remove heat before the liquid enters the pump, preventing heat accumulation in the bulk tank and reducing venting requirements
Solution Approach 2:
The system extracts heat from the liquid hydrogen stream in the sump using a heat exchanger that rejects heat to the environment or to a refrigeration system, separating the thermal management function from the bulk storage tank and preventing heat-induced venting
3Ease of manufacture
If a pump is used instead of a compressor, then equipment cost decreases, but the pump must handle cryogenic liquid which creates vaporization issues
Solution Approach 1:
The system performs preliminary cooling of the liquid hydrogen in the sump using a heat exchanger before it enters the pump, ensuring the liquid remains in a stable cryogenic state and does not vaporize during pumping. This preliminary thermal conditioning prevents vaporization issues and ensures reliable pump operation
Solution Approach 2:
The sump acts as an intermediary thermal management zone that maintains the liquid hydrogen in a stable cryogenic state before delivery to the pump. The heat exchanger in the sump removes heat that would cause vaporization, creating a reliable thermal barrier that protects the pump from vaporization issues
4Speed
If the pump delivers liquid hydrogen directly, then delivery speed increases, but temperature control to the target -33°C becomes difficult
Solution Approach 1:
The patent introduces a vaporizer as an intermediary thermal processing device between the pump and the vehicle. The vaporizer receives cryogenic liquid hydrogen from the pump, vaporizes it, and controls the temperature of the resulting gas stream to match the target -33°C requirement, enabling precise temperature control while maintaining high delivery speed
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
This system reduces heat load on the bulk tank, minimizes venting, and achieves continuous hydrogen delivery with higher subcooling, reducing equipment costs and maintaining efficient thermodynamic performance.
Implementation Method 1
the pump generates subcooling by retaining heat within the sump, preventing it from being returned to the bulk tank
Implementation Method 2
the pump generates subcooling by retaining heat within the sump, preventing it from being returned to the bulk tank and using it to maintain liquid hydrogen in a subcooled state
Implementation Method 3
The sump is designed to be large enough to handle a reasonable duty cycle of liquid delivery and is many times larger in volume than typically used
Implementation Method 4
A first positive displacement pump is positioned within the first sump and is configured to pump
Data Source
AI summary
A system for dispensing a cryogenic fluid includes a bulk tank configured to contain a supply of a cryogenic liquid, a first sump and a first liquid feed valve configured to direct liquid from the bulk tank to the first sump when in an open condition and to prevent transfer of liquid from the bulk tank to the first sump when in a closed condition. A first positive displacement pump is positioned within the first sump and configured to pump and be submerged in cryogenic liquid when the first sump contains cryogenic liquid above a predetermined liquid level within the first sump. A delivery line is in fluid communication with an outlet of the first positive displacement pump and is configured to direct cryogenic fluid from the first positive displacement pump to a use device when the first positive displacement pump is activated.