Ground-Testable Spacecraft Heat Pipe With Bubble-Pump Downward Transport
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Solution Overview
Problem
Existing spacecraft heat pipes struggle to efficiently carry heat downward during ground testing due to the influence of gravity, which leads to puddling of liquid and limitations in reflux operation, necessitating costly and risky workarounds like reorienting the spacecraft or using alternative thermal control technologies.
Innovation Solution
A system combining a grooved wick capillary heat pipe (GWHP) and a bubble pump heat pipe (BPHP) to facilitate heat transfer both upward and downward, utilizing a separator and condenser design to manage fluid flow and pressure differentials, allowing heat to be conducted through a heat acquisition and rejection cold plate system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a conventional heat pipe is used for ground testing, then the heat pipe can operate in reflux mode, but it cannot efficiently carry heat downward when heat input is required at locations above the liquid pool
Solution Approach 1:
The heat pipe is divided into two separate heat pipes: a conventional grooved wick capillary heat pipe (GWHP) for upward heat transport and a bubble pump heat pipe (BPHP) for downward heat transport. Each heat pipe is optimized for its specific function, allowing the system to handle both upward and downward heat transport requirements during ground testing.
Solution Approach 2:
The combined heat pipe system provides multi-functionality by enabling both upward and downward heat transport modes within a single integrated assembly. This allows the spacecraft thermal system to be tested in various orientations and configurations without requiring multiple separate test setups.
2Ease of operation
If the spacecraft is reoriented during ground tests to get heat pipes flat relative to gravity, then downward heat transport becomes possible, but it requires larger vacuum chambers and increases test costs
Solution Approach 1:
By segmenting the heat transport function into two separate heat pipes (GWHP for upward, BPHP for downward), the system eliminates the need to reorient the spacecraft during testing. Each heat pipe handles its designated direction independently, allowing the spacecraft to remain in a fixed, convenient test orientation.
Solution Approach 2:
The bubble pump heat pipe acts as an intermediary device that enables downward heat transport without requiring spacecraft reorientation. It mediates between the heat source and heat sink in a manner that is independent of gravity's directional influence on the conventional heat pipe.
3Ease of operation
If heat is applied to the bottom of heat pipes for test purposes, then downward heat transport can be achieved, but it drives heat pipes to higher operating temperatures and creates more difficult thermal tests
Solution Approach 1:
Instead of applying heat to the bottom of heat pipes (which causes high operating temperatures), the invention applies heat to the top of the BPHP through the separator. This inverted approach allows downward heat transport while maintaining more reasonable operating temperatures, as the heat input location is reversed compared to conventional bottom-heating methods.
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
Enables efficient heat transfer in any vertical orientation, reducing costs and risks associated with ground testing by maintaining thermal performance comparable to in-space conditions, while allowing for flexible installation and post-test removal of components.
Implementation Method 1
causing a plug-slug flow with heated vapor plugs lifting heated liquid slugs
Implementation Method 2
heat is conducted from the spacecraft heat pipe upper section through the HACP into the heat acquisition riser
Implementation Method 3
heated vapor in the separator flows through the vapor condensation conduit into the condenser and condensate liquid mixes with cooled liquid
Data Source
AI summary
A ground testable spacecraft heat pipe has a spacecraft heat pipe thermally connected for conduction of heat through a heat acquisition cold plate to a heat acquisition riser of a bubble pump heat pipe, enabling a plug-slug flow of heated fluid into a separator, with heated liquid flowing downward through a hear rejection downcomer to a heat rejection pipe section mounted on a heat rejection cold plate for conduction of heat to a bottom end of the spacecraft heat pipe, the now-cooled liquid flowing through a heat rejection riser to an outlet in a condenser that receives the heated vapor from the separator through a vapor condensation conduit, the condenser holding the cooled fluid and vapor condensate that exits the condenser through a heat acquisition downcomer to restart the cycle.