Refrigerated Cargo Container Fan Shutdown for In-Flight Fire Control
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Solution Overview
Problem
Refrigerated air cargo containers' exhaust fans can impair airplane smoke detection and fire suppression systems during air transit, and existing detectors may not quickly respond to a variety of fire signatures, leading to potential false alarms and inadequate fire mitigation.
Innovation Solution
The implementation of automatic shutdown systems, including active and passive modes, that utilize a range of sensors (thermal imagery, gas, light intensity, accelerometers, etc.) to detect fire signatures and air transit, allowing for the automatic shutdown or restriction of exhaust fans without human intervention, thereby minimizing false alarms and enhancing fire damage mitigation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If exhaust fans operate continuously to maintain temperature control, then refrigeration efficiency is improved, but fire detection capability and fire suppression effectiveness deteriorate
Solution Approach 1:
The system performs preliminary action by detecting air transit conditions (through barometric pressure sensors, GPS movement detection, or manual input) before the container is loaded onto an aircraft, and automatically shuts down exhaust fans in advance. This prevents the exhaust airflow from interfering with fire detection and suppression systems during air transit, while allowing full refrigeration operation during ground-based transport.
2Temperature
If exhaust fans operate during air transit, then temperature control is maintained, but fire suppression agent dispersal is impaired
Solution Approach 1:
The system detects air transit conditions and shuts down exhaust fans before fire suppression may be needed, ensuring that when fire suppression agents are released, there is no exhaust airflow to disrupt their dispersal and concentration levels.
3Measurement precision
If multiple sensor types are deployed to detect various fire signatures, then fire detection accuracy is improved, but system complexity increases
Solution Approach 1:
The system employs multiple sensor types (smoke detectors, heat detectors, carbon monoxide detectors, barometric pressure sensors, GPS) that each serve multiple functions. For example, barometric pressure sensors detect both air transit conditions and can contribute to fire detection, while GPS tracks location for air transit identification and can detect anomalies indicative of fire events.
4Speed
If automatic shutdown system is implemented, then response time to fire events is reduced, but false alarm risk increases
Solution Approach 1:
The system merges multiple detection methods (smoke detection, heat detection, carbon monoxide detection, barometric pressure changes, GPS movement patterns) and requires corroboration among multiple sensors before triggering automatic shutdown. This multi-sensor verification approach reduces false alarms while maintaining rapid response capability, as the system only shuts down when multiple independent sensors confirm a fire event.
Data Source
AI summary
Automatic shutdown systems are used with refrigerated air cargo containers. When a fire signature is detected by one or more sensors, the container exhaust fan(s) are automatically shut down or their external airflow is automatically restricted. In addition, or in the alternative, the shutdown system may likewise act when air transit is detected, such as acceleration and/or a change in altitude.