Anisotropic Heat Shield for Pressurized Vessel Fire Protection
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Solution Overview
Problem
Conventional pressurized vessels in electric vehicles, such as hydrogen fuel cell vehicles, are vulnerable to rupture due to excessive heat from fires, as conventional pressure relief devices (PRDs) provide only point-source protection and may not activate when the heat source is not in close proximity, leaving large areas of the vessel at risk.
Innovation Solution
A pressure relief system comprising a thermal pressure relief device, a heat shield with anisotropic thermal conductivity, and sensors that activate the PRD when a threshold temperature is reached, ensuring pressure relief regardless of the heat source's location, and optionally including a second pressurized vessel for simultaneous pressure relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pressure relief devices are mounted at discrete locations on the vessel, then the device complexity is reduced, but the reliability of fire protection deteriorates because large areas of the vessel remain exposed to high heat conditions
Solution Approach 1:
The patent transitions from point-source PRD activation to surface-wide activation by conducting heat laterally across the vessel surface. The heat shield with high in-plane thermal conductivity spreads thermal energy from the heat source location to adjacent areas, enabling sensors and PRDs at discrete locations to detect and respond to fires occurring anywhere on the vessel surface.
Solution Approach 2:
The heat shield acts as an intermediary between the heat source and the PRD system. It captures and redistributes thermal energy across the vessel surface, mediating the thermal signal so that discrete sensors and PRDs can detect fires regardless of their precise location relative to the heat source.
2Reliability
If the heat shield conducts heat laterally to activate PRDs, then the reliability of pressure relief is improved, but the heat shield material complexity increases due to anisotropic thermal conductivity requirements
Solution Approach 1:
The heat shield is designed with spatially varying thermal conductivity properties: high in-plane thermal conductivity for lateral heat distribution to activate PRDs, and low through-plane thermal conductivity to insulate the vessel from direct heat exposure. This local quality differentiation enables the shield to simultaneously achieve reliable PRD activation and vessel protection.
Solution Approach 2:
The heat shield employs composite material construction to achieve the required anisotropic thermal conductivity. By combining materials with different thermal properties in a layered or structured configuration, the shield attains high lateral conductivity for heat distribution while maintaining low through-plane conductivity for insulation.
3Device complexity
If conventional PRDs are used with low melting point mechanisms, then the device simplicity is maintained, but the effectiveness deteriorates because they only provide point-source protection and may not activate when heat source is not in close proximity
Solution Approach 1:
The heat shield serves as a thermal intermediary that bridges the gap between distant heat sources and discrete PRD locations. It captures heat from the fire and conducts it laterally to the PRD sensors, ensuring activation even when the heat source is not immediately adjacent to the pressure relief devices.
Solution Approach 2:
The system shifts from relying on direct vertical heat exposure at PRD locations to lateral heat conduction across the vessel surface. This dimensional change in heat transfer enables PRDs at fixed locations to respond to fires occurring anywhere on the vessel by conducting thermal energy across the surface to the sensor locations.
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 insulates and detects heat sources, activating pressure relief devices to prevent vessel rupture, even when the heat source is not directly adjacent to the PRDs, thereby enhancing safety by ensuring simultaneous pressure relief across multiple vessels if needed.
Implementation Method 1
a heat shield positioned adjacent to the first pressurized vessel... at least one of the first pressurized vessel or heat shield comprise a material having a relatively low through-plane thermal conductivity
Implementation Method 2
a first layer configured to conduct thermal energy in a direction corresponding to a length of the heat shield... a material having a relatively high in-plane thermal conductivity
Implementation Method 3
a sensor coupled to at least one of the first pressurized vessel or the heat shield and configured to measure a temperature of the first pressurized vessel or the heat shield
Implementation Method 4
the thermal pressure relief device may comprise a pilot-activated thermal pressure relief device... The thermal pressure relief device may be activated via a smart material or shape memory alloy
Data Source
Figure 1A~1C
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AI summary
A pressure relief system comprises a pressurized vessel containing a fuel source and comprising a thermal pressure relief device, a heat shield coating disposed on an outer surface of the pressurized vessel, a sensor in thermal communication with the heat shield and configured to receive thermal energy from the heat shield, and an electronic control module electrically coupled to the sensor and the thermal pressure relief device. The sensor, responsive to receiving a threshold amount of thermal energy from the heat shield coating, may transmit a signal to the electronic control module. The electronic control module may activate the thermal pressure relief device in response to the signal.