Battery Pack Fire-Extinguishing Conduit for Low-Temperature Cell Fires
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Solution Overview
Problem
Existing battery pack fire-extinguishing systems struggle to effectively extinguish fires at low temperatures, particularly in secondary batteries, leading to potential thermal runaway and propagation of heat to adjacent cells.
Innovation Solution
A direct-spray fire-extinguishing system with a heat-sensitive member that includes a nozzle portion with a thin film design, allowing the system to spray fire-extinguishing agent to the affected cell, even at lower temperatures, by using a heat-sensitive member that melts at 150° C. to 500° C., thereby preventing heat propagation to adjacent cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fire-extinguishing system is used, then it can extinguish fires at high temperatures, but it fails to effectively extinguish fires at low temperatures in secondary batteries
Solution Approach 1:
The patent changes the physical state parameter of the fire-extinguishing agent from liquid to gas by using a refrigerant that evaporates at low temperatures. This phase change enables the system to effectively extinguish fires across a wider temperature range, including low-temperature conditions where conventional liquid-based systems fail.
Solution Approach 2:
The system utilizes the phase transition of the refrigerant from liquid to gas through evaporation. This phase change absorbs heat and produces cold gas that can effectively suppress fires in secondary batteries at low temperatures, while the system can still operate at higher temperatures through controlled evaporation rates.
2Temperature
If a fire-extinguishing agent is sprayed to the affected battery cell, then the temperature of the affected cell and nearby cells can be reduced, but heat may still propagate to adjacent cells
Solution Approach 1:
The patent introduces a refrigerant as an intermediary substance that absorbs heat from the affected battery cell through evaporation. This refrigerant acts as a heat transfer medium, absorbing thermal energy and converting it to latent heat of vaporization, thereby preventing heat propagation to adjacent cells more effectively than direct liquid spraying.
Solution Approach 2:
The system replaces the mechanical kinetic energy-based cooling (liquid spraying) with a thermal phase-change-based cooling mechanism. The refrigerant's phase transition from liquid to gas provides more efficient heat absorption through latent heat, substituting the mechanical impact of liquid spraying with a thermodynamic heat transfer process.
3Strength
If a thick-walled fire-extinguishing conduit is used, then the structural strength is sufficient, but the heat-sensitive member cannot melt at low temperatures to activate spraying
Solution Approach 1:
The fire-extinguishing conduit is segmented into different wall thickness regions: a thicker body portion for structural strength and a thinner nozzle portion for heat-sensitive activation. This segmentation allows the conduit to simultaneously withstand internal pressure while enabling the heat-sensitive member to melt at lower temperatures through the thinner wall section.
Solution Approach 2:
The conduit applies local quality variation by having different wall thicknesses in different locations. The body portion has sufficient thickness for strength, while the nozzle portion has reduced thickness to allow heat penetration and melting of the heat-sensitive member at lower temperatures, enabling localized activation of the fire-extinguishing function.
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 effectively extinguishes fires in secondary batteries by reducing the temperature of affected cells and preventing thermal runaway, ensuring adjacent cells are not affected by heat propagation.
Implementation Method 1
The thin film portion may be configured to be melted at a temperature of about 150° C. to about 500° C.
Implementation Method 2
spray a fire-extinguishing agent to the corresponding battery cell, thereby lowering the temperature of the corresponding battery cell and the temperature of a nearby battery cell
Data Source
AI summary
A battery pack fire-extinguishing system for battery cells includes a fire-extinguishing conduit defining a spray hole for spraying a fire-extinguishing agent to a vent hole in one of the battery cells, and a heat-sensitive member blocking the spray hole, and including a body portion at least partially surrounding a periphery of the fire-extinguishing conduit, and a nozzle portion corresponding to the spray hole, and having a thickness that is less than a thickness of the body portion.