Passive Pressure Control for Cryogenic Storage Tanks
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Cryogenic liquid hydrogen and liquid oxygen storage systems in unmanned underwater vehicles (UUVs) face pressure management challenges due to inability to vent excess gases at deep ocean depths, leading to potential overpressure and tank failure without electronic control systems.
Innovation Solution
A passive, non-electrically controlled pressure management system that uses mechanical switches and valves to draw reactants as gas or liquid from one tank to balance pressures with a separate consumer, such as a fuel cell, without venting to the environment, ensuring safe operation even if electronic systems fail.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional venting systems are used to manage pressure in cryogenic storage tanks, then pressure control is achieved, but the system cannot operate at deep ocean depths where external pressure exceeds venting capability
Solution Approach 1:
The patent replaces the traditional mechanical venting system with a fuel cell-based chemical consumption system. Instead of mechanically venting gases to the environment, the system uses electrochemical reactions in a fuel cell to consume the boil-off gases (hydrogen and oxygen) and convert them into useful electrical energy, thereby maintaining pressure control without requiring mechanical venting capability.
Solution Approach 2:
The fuel cell system serves dual purposes: it generates electrical power for the UUV while simultaneously managing pressure control by consuming the boil-off gases. The system uses the waste thermal energy and gases from the cryogenic storage as inputs, converting them into useful energy and pressure regulation, eliminating the need for separate venting infrastructure.
2Reliability
If electronically controlled valves and fuel cell systems are used for pressure management, then pressure control is achieved, but system complexity and vulnerability to electronic failure increase
Solution Approach 1:
The fuel cell system performs multiple functions simultaneously: it generates electrical power for vehicle operations, manages pressure control by consuming boil-off gases, and provides a backup safety mechanism for pressure relief. This multi-functionality eliminates the need for separate dedicated pressure management systems, reducing overall system complexity while maintaining robust pressure control capability.
3Reliability
If fuel cells consume reactants at stoichiometric ratios to control pressure, then pressure management is achieved, but mismatch between boil-off flow rates and stoichiometric requirements complicates control
Solution Approach 1:
The system dynamically adjusts the operation of multiple fuel cells based on real-time pressure conditions and reactant availability. When one cryogenic tank's pressure exceeds its setpoint, the system activates the corresponding fuel cell to consume that specific reactant, allowing flexible adaptation to varying boil-off rates and maintaining stoichiometric balance without complex manual intervention.
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 effectively manages pressures within cryogenic storage reservoirs without relying on electronic control, preventing overpressure and tank failure, ensuring safe operation and energy efficiency in UUVs and other vehicles using cryogenic reactants.
Implementation Method 1
a consumer 207 that combines the reactants. The consumer may be a fuel cell
Implementation Method 2
a back pressure regulator 212 that is openable when a pressure within the second reservoir 202b exceeds a reference pressure
Data Source
AI summary
An all mechanically controlled, non-venting pressure control system for liquid hydrogen and liquid oxygen cryogenic tanks that requires no electrical control while managing disparate, non-stoichiometric reactant boil-off rates is provided. The pressure control system allows for the passive and repeatable stoichiometric consumption of hydrogen and oxygen boil-off from cryogenic tanks to form liquid water, while preventing the liquid hydrogen and liquid oxygen cryogenic tanks from overpressurizing and venting to the external environment. More particularly, in response to an overpressure condition in a first reactant reservoir, a backpressure regulator is opened, providing the overpressure first reactant to a fuel cell or other consumer, and providing a pilot signal to open a supply line from a second reactant reservoir to the consumer. Whether the second reactant is supplied from the second reactant reservoir as gas or a liquid is determined based on the pressure within the second reactant reservoir.