Stratospheric Capsule PCM Cooling for Temperature and Humidity
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Solution Overview
Problem
Existing environmental control systems for stratospheric capsules fail to effectively manage temperature and humidity variations between sea level and 100,000 ft, as they are not suited for the extreme pressure and temperature fluctuations experienced during stratospheric flights.
Innovation Solution
A thermal control system utilizing a pumped coolant loop with an internal air-cooling heat exchanger, external heat rejection assembly, and phase change material (PCM) heat exchange assembly, dynamically managing heat rejection between these components via modulating valves to maintain temperature and humidity within a comfortable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional environmental control system is used, then the system structure is simple, but it fails to effectively manage temperature and humidity variations during stratospheric flights
Solution Approach 1:
The environmental control system is divided into multiple independent components: an internal air-cooling heat exchanger for cooling cabin air, an external heat rejection assembly for dissipating heat to the external environment, and a phase change material heat exchange assembly for thermal energy storage. Each component handles a specific aspect of thermal management, allowing the system to effectively manage temperature and humidity variations during stratospheric flights while maintaining modular complexity.
Solution Approach 2:
The system utilizes phase change material that transitions between solid and liquid states to absorb and release thermal energy. This parameter change (phase transition) enables the system to store and release large amounts of thermal energy without significant temperature change, effectively managing temperature variations during altitude changes from sea level to 100,000 ft.
2Adaptability or versatility
If the capsule flies between sea level and 100,000 ft, then the operational altitude range is extended, but the temperature and pressure fluctuations become extreme
Solution Approach 1:
The phase change material heat exchange assembly pre-cools the cooling fluid during periods when external conditions are favorable (lower altitudes or nighttime), storing thermal energy in the phase change material. This preliminary cooling action prepares the system for periods of high thermal load at higher altitudes, enabling the capsule to maintain stable internal temperatures across the extreme altitude range from sea level to 100,000 ft.
Solution Approach 2:
The system employs phase change material that undergoes solid-liquid phase transitions to absorb excess heat when the capsule ascends to high altitudes and releases heat when descending. This phase transition mechanism provides passive thermal regulation that complements the active cooling system, enabling the capsule to adapt to temperature fluctuations between approximately 100°F at sea level and -130°F at 100,000 ft.
3Duration of action of moving object
If heat rejection is performed continuously, then the temperature control is maintained, but the operational time is limited due to energy constraints
Solution Approach 1:
The external heat rejection assembly operates periodically rather than continuously. The system uses the phase change material to store thermal energy during periods when external heat rejection is not needed (such as during nighttime or at lower altitudes), and releases this stored energy during periods of high thermal load. This periodic operation reduces overall energy consumption while maintaining temperature control throughout the extended operational duration of stratospheric flights.
Solution Approach 2:
The phase change material heat exchange assembly extracts and stores thermal energy separately from the main cooling cycle. By removing this thermal energy storage function from the continuous active cooling system, the design allows the primary cooling system to operate only when necessary, thereby extending operational time while reducing overall energy consumption during stratospheric missions.
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 provides efficient temperature and humidity control across a wide altitude range by using a cascaded control logic, extending operational time and enabling simultaneous regulation of cabin temperature and humidity.
Implementation Method 1
an internal air-cooling heat exchanger that cools air within the capsule with by passing air across a cooling fluid within the ECS
Implementation Method 2
an external heat rejection assembly fluidly connected to the internal air-cooling heat exchanger and located on or outside of the capsule exterior, external heat rejection assembly configured to rejected heat from the cooling fluid to external air
Implementation Method 3
a phase change material (PCM) heat exchange assembly located within the capsule interior and fluidly connected to the external heat rejection assembly and the internal air-cooling heat exchanger
Data Source
AI summary
A stratospheric capsule includes: a capsule interior configured to enclose occupants during a stratospheric space flight; a capsule exterior; and an environmental control system (ECS) configured to control one or more of temperature and humidity in the capsule interior during the stratospheric space flight. The ECS includes: an internal air-cooling heat exchanger that cools air within the capsule by passing air across a cooling fluid within the ECS and a phase change material (PCM) heat exchange assembly located within the capsule interior. First and second valves are arranged and configured to be controlled based on the temperature measured by the temperature sensor measuring air passing through the internal air-cooling heat.