Fuel Cell Flammable Gas Sensor Sensitivity Assessment
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Solution Overview
Problem
It is challenging to determine if the detection sensitivity of a flammable gas sensor in a fuel cell system has deteriorated, as existing structures make it difficult to assess the sensor's performance within the housing.
Innovation Solution
A fuel cell system design that includes a flammable gas sensor positioned in a discharge passage downstream of the merging point of ventilated air and combustion exhaust gas, allowing for the detection of leaked gases and using an instruction concentration to assess the sensor's sensitivity through output values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flammable gas sensor is housed inside the housing with the fuel cell system, then the sensor can detect gas leaks within the system, but it becomes difficult to assess whether the sensor's detection sensitivity is deteriorating
Solution Approach 1:
The patent introduces a discharge passage as an intermediary channel that connects the housing interior to the exterior. This passage allows a controlled amount of flammable gas to be discharged from the housing for external detection, serving as a mediator between the sensor's internal monitoring function and the need for external sensitivity assessment. The discharge passage enables the sensor to detect both actual leaks and controlled test gas flows.
Solution Approach 2:
The system performs preliminary sensitivity assessment by controlling the discharge of flammable gas through the discharge passage before actual gas leak detection is needed. By pre-establishing a known concentration of flammable gas in the discharge passage and measuring the sensor's response, the system can evaluate sensor sensitivity without requiring actual leak conditions to occur.
2Measurement precision
If the sensor is positioned to detect leaked gases in the housing, then it can monitor for actual leaks, but there is no way to provide a known gas concentration for sensitivity testing
Solution Approach 1:
The discharge passage serves multiple functions: it acts as a normal exhaust path for combustion exhaust gas during regular operation, and simultaneously serves as a test gas delivery path for sensor sensitivity assessment. By controlling the discharge of flammable gas through this same passage, the system creates a universal structure that supports both monitoring and testing functions without requiring separate dedicated pathways.
Solution Approach 2:
The system uses its own flammable gas supply and discharge infrastructure to perform self-diagnosis of sensor sensitivity. Rather than requiring external test equipment or separate test chambers, the fuel cell system utilizes its existing gas storage, control valves, and discharge passage to generate and deliver known concentrations of flammable gas to the sensor for automatic sensitivity assessment.
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
Enables effective detection of flammable gas leaks and periodic assessment of sensor sensitivity without disrupting the fuel cell system's operation, ensuring accurate leakage detection and maintaining system performance.
Implementation Method 1
a flammable gas sensor provided at a sensor arranging portion positioned in the discharge passage at downstream side of a merging point of the ventilated air and the combustion exhaust gas for detecting a concentration of the flammable gas
Implementation Method 2
a combustion portion which burns an anode off gas from the fuel cell and a cathode off gas from the fuel cell to generate a combustion exhaust gas
Implementation Method 3
a fuel cell which generates electricity by the electro-chemical reaction of the fuel gas and oxidant gas
Data Source
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AI summary
A fuel cell system (100) includes a fuel cell (34) which generates electricity by fuel supplied to an anode (34p) and an oxidant gas supplied to a cathode (34q), a combustion portion (36) which burns an anode off gas from the fuel cell (34) and a cathode off-gas from the fuel cell to generate a combustion exhaust gas, a casing (31) formed by a heat-insulating material and accommodating therein the fuel cell (34) and the combustion portion (36), a housing (10a) which accommodates the casing (31) therein and provided with a ventilation discharge port (10d) discharging the air ventilated inside the housing (10a) out of the housing (10a), a discharge passage (50) connected to the casing (31) and discharging the combustion exhaust gas flowing from the casing out of the housing (10a), a flammable gas sensor (58) provided at a sensor arranging portion (60) positioned in the discharge passage (50) at downstream side of a merging point (57) of the ventilated air and the combustion exhaust gas for detecting a concentration of the flammable gas, an instructing portion (15) instructing the flammable gas to flow through the sensor arranging portion (60) with an instruction concentration (C1) and a judging portion (15) which judges whether or not a detection sensitivity of the flammable gas sensor (58) is deteriorated based on an output value (V1) of the flammable gas sensor (58) relative to the instruction concentration (C1).