CNG Fuel Tank Bypass Valves for Rapid Thermal Event Venting
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Solution Overview
Problem
Refuse collection vehicles using compressed natural gas (CNG) face challenges in effectively venting gas during thermal events, leading to potential fires and explosions due to delayed activation of pressure relief devices, especially when tanks away from the fire do not activate promptly.
Innovation Solution
A fuel system for refuse collection vehicles that includes a bypass mechanism for pressure relief devices, activated by sensors detecting conditions like pressure drops or flow changes, to quickly vent gas from all tanks, even if individual relief devices fail to activate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pressure relief devices are used on fuel tanks, then gas venting is enabled, but delayed activation occurs during thermal events especially for tanks away from the fire
Solution Approach 1:
The system performs preliminary action by detecting thermal events before pressure relief devices are needed and pre-activating bypass valves to enable immediate venting. The control system monitors temperature sensors and automatically opens bypass valves around affected tanks before pressure buildup occurs, eliminating the delayed activation problem of conventional pressure relief devices.
Solution Approach 2:
The bypass valve acts as an intermediary mechanism between the thermal event detection and the fuel tank venting system. When a thermal event is detected, the bypass valve opens to provide an alternative venting path that bypasses the slow-responding pressure relief devices, enabling faster gas discharge from affected tanks.
2Object-affected harmful factors
If pressure relief devices are activated, then gas venting occurs, but tank rupture and damage risk remains due to delayed response
Solution Approach 1:
The control system performs preliminary action by detecting thermal events through temperature sensors and automatically activating bypass valves before pressure relief devices are triggered. This early intervention prevents pressure buildup that could lead to tank rupture, addressing the harmful effect before it manifests.
Solution Approach 2:
The system applies preliminary anti-action by preemptively opening bypass valves when thermal events are detected, counteracting the potential harmful effect of pressure buildup and tank rupture before it occurs. This preventive approach neutralizes the threat of tank damage before the conventional pressure relief devices can respond.
3Loss of substance
If conventional pressure relief devices are used, then gas venting is achieved, but fuel loss occurs due to delayed venting activation
Solution Approach 1:
The system performs preliminary action by detecting thermal events and immediately activating bypass valves to vent gas before pressure relief devices would trigger. This early venting prevents excessive fuel loss that would occur with delayed activation, as the bypass system opens instantly upon thermal event detection.
Solution Approach 2:
The control system uses feedback from temperature sensors to automatically activate bypass valves when thermal conditions are detected. This closed-loop feedback mechanism ensures immediate response to thermal events, venting gas before significant fuel loss can occur, unlike conventional systems that rely on pressure buildup triggers.
4Object-affected harmful factors
If pressure relief devices are activated, then gas venting occurs, but explosion risk remains due to delayed response time
Solution Approach 1:
The control system performs preliminary action by detecting thermal events through temperature sensors and immediately activating bypass valves to vent gas before pressure relief devices trigger. This early intervention eliminates the time delay that allows explosive conditions to develop, as the bypass system provides immediate venting capability.
Solution Approach 2:
The bypass valve mechanism allows the system to skip the delayed activation phase of conventional pressure relief devices and rush through to immediate gas venting. When thermal events are detected, the bypass system activates instantly, rushing the venting process through before explosive conditions can manifest.
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 reduces the time for venting gas, decreases the risk of tank rupture and damage, prevents loss of fuel, and minimizes the risk of explosions, providing early intervention and protection against thermal events.
Implementation Method 1
opening the pressure relief device bypass valve so that the fuel tank is vented to the atmosphere
Implementation Method 2
each of the at least two fuel tanks includes a pressure relief device in fluid communication with the fuel tank and configured to open in response to a pressure differential between the fuel tank and the atmosphere
Data Source
AI summary
A method of protecting a refuse collection vehicle from damage includes detecting a condition associated with a thermal event on the refuse collection vehicle. In response to detecting the condition associated with the thermal event on the refuse collection vehicle, one or more pressure relief devices coupled to one or more fuel tanks are bypassed such that gas from is vented from the fuel tanks.