Cryogenic Liquid Acquisition Device for Thermal De-stratification
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Solution Overview
Problem
In a low-gravity environment, cryogenic tanks face challenges in reliably venting the gaseous phase to prevent over-pressurization and minimizing temperature increases, which leads to boil-off of the cryogenic liquid, making it difficult to maintain the propellant in a usable state for extended-duration missions.
Innovation Solution
A fluid management system that includes a liquid acquisition device and a spray injection system, where the liquid is sprayed into the bulk tank fluid for thermal destratification and pressure reduction, utilizing primary and secondary heat exchangers to chill the liquid and vent excess heat to the exterior, thereby controlling temperature and pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct venting is used from the forward end of the tank, then gaseous phase can be vented in high-gravity environments, but liquid phase may be expelled in low-gravity environments
Solution Approach 1:
A liquid acquisition device acts as an intermediary component between the tank interior and the vent system. It selectively acquires liquid phase cryogenic propellant and directs it to a spray injection system, while allowing gaseous phase to pass through to the vent. This mediator prevents liquid expulsion during venting in low-gravity environments while maintaining reliable venting capability.
2Stability of the object's composition
If tank internal pressure is increased to prevent vaporization, then liquid cryogenic fluid can be maintained, but tank structural limits may be exceeded
Solution Approach 1:
The liquid acquisition device extracts liquid phase cryogenic propellant from the tank interior selectively, separating it from the gaseous phase. By removing only the liquid phase for spraying and venting, the system maintains pressure control within structural limits while preventing vaporization of the remaining liquid propellant in the tank.
3Temperature
If cryogenic fluid is heated from radiation and heat sources, then tank internal pressure increases, but this causes continuous boil-off of liquid cryogen
Solution Approach 1:
The spray injection system changes the temperature parameter of the cryogenic propellant by injecting cold liquid spray into the warmed tank environment. This localized cooling counteracts the temperature increase from radiation and heat sources, reducing thermal boil-off and maintaining lower tank internal temperature while controlling pressure.
4Temperature
If liquid cryogenic propellant is sprayed into bulk tank fluid, then thermal destratification and pressure reduction occur, but system complexity increases
Solution Approach 1:
The fluid management system is segmented into distinct functional components: a liquid acquisition device for selective liquid phase acquisition, a spray injection system for controlled liquid injection, and a vent system for pressure relief. This segmentation allows each component to perform its specific function efficiently, achieving thermal destratification and pressure control while maintaining manageable system complexity through modular design.
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 reduces thermal stratification and pressure within the tank, minimizing boil-off and ensuring a reliable supply of cryogenic propellant by maintaining the gaseous phase for venting while keeping the liquid phase intact, thus optimizing the use of propellant during space missions.
Implementation Method 1
The spraying of the liquid into the bulk tank fluid provides forced convection mixing of the spray with the bulk tank fluid resulting in thermal destratification and pressure reduction in the tank
Implementation Method 2
The liquid acquisition device may include a surface tension basket that receives the liquid from the bulk tank fluid and that retains the liquid within the liquid acquisition device
Data Source
AI summary
A fluid management system for a cryogenic tank may include a liquid acquisition device and a spray injection system. The cryogenic tank may include a tank wall and may contain bulk tank fluid. The liquid acquisition device may acquire and contain cryogenic fluid in substantially liquid phase. The liquid acquisition device may be mounted in spaced relation to the tank wall. The spray injection system may receive the liquid from the liquid acquisition device and may spray the liquid into the bulk tank fluid.