Battery Pack Flow Control for Thermal Runaway Containment
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Solution Overview
Problem
Aircraft battery packs face the risk of thermal runaway, which can lead to cell failure propagation and potentially catastrophic events such as fires or explosions, due to undetectable defects or operational abuses, and existing technologies do not adequately address the severity of these risks in aerospace applications while considering weight and power density constraints.
Innovation Solution
A battery pack design incorporating a plurality of battery cells, flow control devices, and sensing and control circuitry that measures parameters indicative of thermal runaway, activating fluid flow to cool cells and vent gases away from the cells, using flame retardant fluids and passive or active flow control devices to mitigate the risk of failure propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flow control devices are continuously activated to cool cells and vent gases, then thermal runaway propagation is prevented, but weight and power consumption increase
Solution Approach 1:
The flow control devices are designed to be dynamically controllable, switching between active cooling/venting modes and standby modes based on real-time temperature and pressure sensor data. This allows the system to provide protection only when thermal runaway is detected, rather than continuously operating, thereby reducing weight and power consumption while maintaining reliability.
Solution Approach 2:
The battery pack system monitors its own thermal state through integrated sensors and automatically activates flow control devices only when abnormal temperature or pressure conditions are detected. This self-service approach eliminates the need for continuous external monitoring and intervention, reducing overall system weight while maintaining safety.
2Reliability
If flame retardant fluids are used in large quantities for cooling and venting, then thermal runaway propagation is suppressed, but power density is reduced
Solution Approach 1:
Flame retardant fluids are applied locally only to specific high-risk areas such as cell terminals, inter-cell connectors, and vent pathways rather than uniformly throughout the entire battery pack. This localized application provides effective thermal runaway suppression at critical propagation points while minimizing the total volume of fluid required, thereby preserving power density.
Solution Approach 2:
The system uses sensors to detect temperature and pressure parameters that indicate approaching thermal runaway conditions, activating flow control devices only when these parameters exceed predetermined thresholds. This parameter-based activation allows the use of smaller amounts of flame retardant fluid compared to continuous flooding, maintaining power density while ensuring reliability.
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 significantly reduces the likelihood of cell failure propagation by cooling the cells and preventing combustible gas buildup, thereby limiting the development and propagation of thermal runaway events, while maintaining efficiency and optimizing power density.
Implementation Method 1
direct a flow of fluid past one or more of the plurality of cells to cool the cells
Implementation Method 2
cool the cells and/or carry media vented by one or more of the cells following a thermal runaway event away from the one or more cells
Implementation Method 3
carry media vented by one or more of the cells following a thermal runaway event away from the one or more cells
Implementation Method 4
direct a flow of fluid past one or more of the plurality of cells to cool the cells and/or carry media vented
Data Source
AI summary
Battery packs, which may be used in vehicles, include: a plurality of battery cells; one or more flow control devices; and sensing and control circuitry configured to: measure one or more parameters indicative of an onset of thermal runaway of one or more of the plurality of cells; determine, based on a change in one or more of the measured parameters, that one or more of the plurality of battery cells has begun or is at risk of beginning thermal runaway; and activate one or more of the flow control devices in response to the determination. Each of the one more flow control devices is configured to, when activated, direct a flow of fluid past one or more of the plurality of cells to cool the cells and/or carry media vented by one or more of the cells following a thermal runaway event away from the one or more cells.