Thermally Integrated Cryogenic Tank Pressurization
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Solution Overview
Problem
In low-gravity environments, such as those encountered in space travel to the moon or Mars, liquid hydrogen and oxygen propellants adhere to tank walls, making it difficult to determine their quantity and pressurize tanks effectively, as conventional pressurization systems like helium are impractical due to the lack of indigenous resources and issues with condensation and pressure management.
Innovation Solution
A thermally integrated pressurization system using cryogenic liquid oxygen and hydrogen tanks, supercritical oxygen and hydrogen bottles, thermal switches, and a pressure management system that regulates heat flow and pressure by sensing conditions and adjusting with gaseous oxygen and hydrogen to maintain optimal tank pressures and prevent boil-off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If liquid hydrogen and oxygen are stored in cryogenic tanks in low-gravity environment, then the propellants can be stored for long duration space flights, but the liquid propellants adhere to tank walls making it difficult to determine quantity and pressurize tanks
Solution Approach 1:
The system divides the single pressurization function into multiple components: thermal switches segment the heat flow paths, supercritical bottles separate pressurization gas storage from liquid propellant storage, and the pressure management system segments control functions. This segmentation allows pressurization gases to be introduced from supercritical bottles rather than relying on conventional methods that fail in low-gravity.
Solution Approach 2:
The system changes the physical state parameter of the pressurization gas by using supercritical oxygen and hydrogen instead of conventional gaseous or liquid pressurants. These supercritical fluids can be easily converted to gas phase for pressurization, solving the adhesion problem while enabling effective tank pressurization in low-gravity environments.
2Reliability
If separate gaseous helium system is used for pressurization, then tank pressure can be maintained for proper engine operation, but large amounts of helium are needed which are not readily available on the moon or Mars
Solution Approach 1:
The system uses the propellant molecules themselves (oxygen and hydrogen) in their supercritical state to provide pressurization, rather than requiring separate helium supplies. The supercritical bottles contain the same substances that will be used as propellants, allowing the system to pressurize itself using indigenous resources that would be available on the moon or Mars.
Solution Approach 2:
The supercritical oxygen and hydrogen bottles serve dual functions: they store pressurization gases for tank pressurization and also serve as the propellant supply for the main engine. This eliminates the need for separate helium pressurization systems and reduces the total quantity of substances needed.
3Stress or pressure
If pressurization gas is introduced into cryogenic tanks, then tank pressure increases for proper operation, but the gas may condense into liquid propellants in low-gravity environment
Solution Approach 1:
The system changes the temperature and pressure parameters of the pressurization gas by storing it in supercritical state in thermally isolated bottles. When needed, the supercritical fluid can be controlled to vaporize and introduce gas phase pressurization into the cryogenic tanks, preventing condensation while maintaining effective pressure.
Solution Approach 2:
The supercritical bottles act as an intermediary between the external environment and the cryogenic propellant tanks. They provide a controlled interface where pressurization gas can be generated and regulated before being introduced to the cryogenic tanks, preventing direct condensation issues.
4Temperature
If thermal insulation is provided to prevent heat transfer, then propellant temperature is maintained, but the system cannot actively manage pressure variations and prevent boil-off
Solution Approach 1:
The system replaces static thermal insulation with dynamic thermal management using controllable thermal switches. These switches can actively open or close heat flow paths between the propellant tanks and the environment or heat sinks, allowing the system to dynamically respond to pressure variations and prevent boil-off by controlling heat transfer in real-time.
Solution Approach 2:
The pressure management system incorporates feedback control by monitoring tank pressure and temperature conditions, then activating or deactivating thermal switches and supercritical bottle venting accordingly. This closed-loop feedback allows active management of both temperature and pressure to prevent boil-off and maintain reliable operation.
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 enables efficient autogenous generation of pressurization gases, effective pressure management, and minimizes propellant loss by actively controlling temperature and pressure, allowing for reliable operation in dynamic low-gravity conditions and the use of indigenous resources like water ice for propellant production.
Implementation Method 1
The supercritical bottle is coupled to a thermal switch that conducts heat, as needed, for cooling and heating the tanks and supercritical bottles
Implementation Method 2
Some or all of these may be coupled to thermal switches that conduct heat, as needed, for cooling and heating the tanks and supercritical bottles
Implementation Method 3
The apparatus includes supercritical oxygen bottles and supercritical hydrogen bottles to be charged with pressurized supercritical fluid forms of the propellant
Data Source
AI summary
A propulsion system may be operated by determining pressure in a cryogenic liquid tank storing a fluid and cooling the cryogenic liquid tank in response to determining that the pressure is greater than a predetermined value. The cryogenic liquid tank may be pressurized by admitting a gaseous form of the fluid into the cryogenic liquid tank in response to determining that the pressure in the cryogenic liquid tank is less than a predetermined value.