Two-Phase Venting Thermal Management for High-Pressure Environments
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Solution Overview
Problem
Current thermal management systems face challenges in high-temperature and high-pressure environments due to limitations in vapor pressure of working fluids, leading to inefficiencies in heat rejection and increased system mass, particularly in celestial body exploration and aircraft applications.
Innovation Solution
The introduction of a secondary species in a venting vessel with a two-phase working fluid increases the total pressure, allowing effective vaporization and heat rejection into high-pressure environments, with the system utilizing a primary vessel for heat acquisition and venting, and a secondary vessel for pressure augmentation, enabling efficient heat management with minimal energy and mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a two-phase working fluid is vented into a high-pressure environment, then heat rejection is achieved through vaporization, but the vapor pressure of the working fluid is insufficient to overcome the environmental pressure
Solution Approach 1:
A secondary species (non-condensable gas) is introduced as an intermediary to bridge the pressure gap. The secondary species increases the total pressure of the vented mixture, enabling the working fluid vapor to overcome the high environmental pressure and achieve effective heat rejection. The secondary species acts as a mediator that allows the primary working fluid to function in environments where it would otherwise be unable to operate.
2Temperature
If Phase Change Material is used as a primary heat sink to absorb waste heat, then the electronics temperature can be maintained within required limits, but the system mass increases significantly
Solution Approach 1:
The system utilizes phase transition of a two-phase working fluid (liquid to vapor) to absorb and reject heat. When the working fluid vaporizes, it absorbs latent heat from the electronics, maintaining temperature control. This phase change mechanism provides efficient thermal management with significantly reduced mass compared to traditional PCM heat sinks.
Solution Approach 2:
The invention changes the operating parameters by introducing a secondary species that modifies the total pressure of the vented mixture. This parameter change enables the system to operate in high-pressure environments while maintaining effective heat rejection, achieving both temperature control and mass reduction goals.
3Stress or pressure
If the total pressure of the venting vessel is increased by adding a secondary species, then heat rejection into high-pressure environments becomes effective, but the system complexity increases
Solution Approach 1:
The secondary species serves multiple functions simultaneously: it increases the total pressure to overcome environmental pressure, acts as a carrier gas for the working fluid vapor, and can be stored in a separate reservoir for on-demand introduction. This multi-functionality achieves high pressure capability without proportionally increasing system complexity.
Solution Approach 2:
The system is segmented into functional components: a primary chamber containing the two-phase working fluid, a secondary species reservoir, and controlled introduction mechanisms. This segmentation allows independent optimization of each component and simplifies the overall system architecture while achieving the required pressure capabilities.
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 solution allows for effective heat rejection in high-pressure environments, maintaining low system mass and simplicity, with no moving parts other than valves, and enables extended operation in extreme conditions by leveraging the latent and sensible heat capacities of the fluid mixture.
Implementation Method 1
This is achieved by elevating the total pressure of a venting vessel through the addition of a secondary species (i.e., non-condensable gas) into the venting vessel that is charged with working fluid at saturation
Implementation Method 2
the waste heat of the payload can be effectively rejected through working fluid vaporization
Implementation Method 3
The resulting total pressure consisting of vapor saturation pressure and gas partial pressure will be higher than the environmental pressure. By venting this mixture (saturated working fluid and the secondary species) into the high-pressure environment, the waste heat of the payload can be effectively rejected through working fluid vaporization
Implementation Method 4
Waste heat generated by the electronics and absorbed from the hot engine environment is transported to fuel channels primarily by conduction through the aluminum support structure
Implementation Method 5
the internal electronic heat load is cooled by the sensible heat of ammonia liquid from 0° C. to 70° C.
Data Source
AI summary
A thermal management system adapted to vent a two-phase working fluid into an environment having a higher pressure than a vapor pressure of a working fluid corresponding to a set point of the system including a secondary vessel containing a secondary species. The system includes a primary vessel containing the working fluid and the secondary species, and at least one valve to selectively control venting of a mixture of the working fluid and the secondary species from the primary vessel to the environment. The system includes at least one valve connected between the primary vessel and the secondary vessel to selectively control charging of the secondary species into the primary vessel.