OBOGS Composition Control with Adaptive Bed Cycling
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Solution Overview
Problem
Existing PSA systems for aircraft onboard oxygen generation struggle to maintain sufficient oxygen delivery during high demand or sieve efficiency degradation, while minimizing power consumption, bleed air usage, and pressure drop.
Innovation Solution
A control system that transitions between unbalanced and balanced bed cycling modes based on demand, using a feedback gain control to optimize oxygen production and efficiency, seamlessly adjusting bed cycle times to meet varying oxygen demands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple separate tanks are used to store different density components, then composition control is improved, but device complexity increases
Solution Approach 1:
The storage system is segmented into multiple separate tanks, each dedicated to storing a specific density component (light component and heavy component). This segmentation enables independent control and monitoring of each component, improving composition control precision while maintaining manageable system complexity through modular architecture.
Solution Approach 2:
A blending tank serves as an intermediary between the separate storage tanks and the final product. The blending tank receives components from different density tanks, mixes them to achieve target specifications, and then delivers the blended product. This intermediary structure enables precise composition control without requiring direct complex interactions between all storage systems.
2Loss of time
If blending is performed before storage, then product availability is improved, but harmful factors increase due to evaporation and contamination
Solution Approach 1:
Components are pre-stored in separate tanks in their pure states before blending is required. This preliminary storage action allows components to be kept in optimal conditions (minimizing evaporation and contamination) while still being ready for rapid blending when needed, thus maintaining product availability without exposing finished product to harmful factors during storage.
Solution Approach 2:
The harmful factors (evaporation and contamination risks) are extracted from the storage phase by keeping components separate. Instead of storing blended product that is vulnerable to these harmful factors, the system stores pure components in sealed separate tanks, eliminating the risks during the storage period while enabling quick blending when product is needed.
3Manufacturing precision
If components are stored separately by density, then composition control is improved, but loss of substance increases due to evaporation
Solution Approach 1:
The system segments the storage into multiple sealed tanks based on density, with each tank storing a specific component. This segmentation allows for optimized sealing and vapor space management for each component type, reducing overall evaporation losses while maintaining the composition control benefits of separate storage. The modular tank design enables better vapor recovery systems to be implemented for each component.
Data Source
Figure 1~2
AI summary
A control system for an onboard oxygen generating system (OBOGS) includes a gain control communicatively coupled to an oxygen sensor configured to measure an oxygen concentration outputted from the OBOGS. The gain control selectively switches between unbalanced and balanced bed cycling modes of the OBOGS to produce a target oxygen concentration based on demand. A corresponding method includes providing a gain control communicatively coupled to an oxygen sensor configured to measure an oxygen concentration outputted from the OBOGS, controlling the OBOGS to operate in the unbalanced bed cycling mode when a low demand is placed on the OBOGS whereby the gain control provides a short bed cycle and a corresponding long cycle of a fixed cycle time, and switching the OBOGS to operate in the balanced bed cycling mode when a high demand is placed on the OBOGS. The balanced bed cycling mode operates at a decreased bed cycle time.