Stratospheric Balloon Thermal Control via Partial Cover and Active Venting
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Solution Overview
Problem
Lighter-than-air high-altitude platforms (HAPs) operating in the stratosphere face challenges due to diurnal temperature changes and environmental conditions, which cause pressure fluctuations, reducing their lifespan and operational duration.
Innovation Solution
A balloon configuration with a partial covering and active air venting system, including a ventilation assembly and air intake assembly controlled by a temperature and pressure sensing system, to regulate temperature and maintain a stable pressure, thereby enhancing the balloon's longevity and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the balloon envelope is fully exposed to the environment, then the balloon can operate with simpler structure and lower weight, but the temperature fluctuations and pressure changes increase, reducing the balloon's lifespan
Solution Approach 1:
The balloon envelope is divided into two functional sections: an exposed upper section and a covered lower section. The cover portion is selectively applied to the lower envelope where temperature regulation is most critical, while the upper envelope remains exposed. This segmentation allows the system to protect against harmful thermal effects without completely enclosing the balloon, thus extending lifespan while maintaining structural simplicity.
Solution Approach 2:
The protective cover is applied locally to specific portions of the envelope rather than covering the entire surface. The cover portion has different properties (thermal protection) than the exposed portions, creating local quality variations that address temperature fluctuations where they matter most while leaving other areas simple and lightweight.
2Duration of action of stationary object
If a protective cover is added to the balloon envelope, then temperature fluctuations are reduced and lifespan is extended, but the balloon weight and structural complexity increase
Solution Approach 1:
The cover is segmented to cover only the lower portion of the envelope where thermal protection is most beneficial, rather than enclosing the entire balloon. This reduces the total material required and minimizes weight addition while still providing protective effects in critical areas.
Solution Approach 2:
Instead of fully enclosing the balloon envelope, the invention applies partial coverage with the protective cover. This partial action is sufficient to reduce temperature fluctuations and extend lifespan without the excessive weight and complexity of complete enclosure.
3Temperature
If the balloon envelope is fully enclosed, then temperature regulation is improved, but the pressure control complexity and energy consumption increase
Solution Approach 1:
The envelope is segmented into covered and exposed sections, creating a hybrid thermal environment. This partial enclosure provides some temperature stabilization without the extreme temperature control challenges of full enclosure, thereby reducing the complexity of pressure control systems needed to compensate for thermal effects.
Solution Approach 2:
The covered lower section provides localized thermal protection where it is most needed, creating a gradient of thermal protection. This local quality approach moderates temperature fluctuations without creating the uniform extreme conditions that would require complex pressure control systems.
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 solution effectively reduces temperature fluctuations within the balloon, minimizing stress on the envelope and allowing for the use of thinner materials, which increases payload capacity and extends the operational duration of the HAPs.
Implementation Method 1
The envelope cover is configured to maintain heat within the envelope and reflect light away from the envelope
Implementation Method 2
The control system is configured to sense at least one of temperature or pressure within the envelope and, in response to the sensed at least one of temperature or pressure, is also configured to cause the ventilation assembly to expel air from within the envelope
Implementation Method 3
The control system may be configured to maintain the selected pressure to achieve a buoyancy requirement of the balloon
Data Source
AI summary
Aspects of the technology relate to temperature regulation for high altitude, long duration balloons, such as balloons that operate in the stratosphere for weeks, months or longer. A balloon covering overlays the balloon envelope, providing an opaque or otherwise light-reflective layer with low emissivity that blocks or reflects optical and/or infrared light. Heat from within the envelope is reflected back from the covering toward the envelope, while light from the sun is reflected back towards the environment. An active venting system is employed to draw in cooler ambient air from the external environment while expelling warmer air from within the envelope. Vent and air intake assemblies of the active venting system are actuated in view of current and/or predicted balloon conditions to regulate internal balloon temperature. This approach reduces repeated pressure changes, which can put undue stress on the balloon envelope and adversely affect the operational lifespan of the system.