Fuel Cell Controller Obstruction Detection
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Solution Overview
Problem
During low-efficiency operation of fuel cell systems, reduced air flow rates lead to hydrogen ion and electron re-bonding at the air electrode, producing 'pumping hydrogen' which is diluted and discharged, but insufficient dilution can result in high hydrogen concentration in exhaust air, causing air flow path obstruction and fuel cell degradation, with existing methods unable to determine or address this obstruction effectively.
Innovation Solution
A fuel cell system with a controller that adjusts oxidant gas flow rate and voltage, including sensors for temperature, voltage, and current, to determine the degree of air flow path obstruction and initiate a blow operation to increase flow rate and transition from low-efficiency to normal operation, thereby preventing obstruction and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the flow rate of air supplied to the fuel cell is reduced to execute low-efficiency operation, then the thermal loss is increased and warm-up performance is improved, but the hydrogen concentration in exhaust air becomes high and air flow path obstruction occurs
Solution Approach 1:
The controller determines the degree of air flow path obstruction by calculating the air concentration overvoltage based on fuel cell voltage and air stoichiometric ratio, and uses this feedback information to control the air supply flow rate, preventing obstruction during low-efficiency operation
Solution Approach 2:
The system dynamically adjusts the air supply flow rate parameter based on the calculated obstruction degree, changing the flow rate from reduced (during low-efficiency operation) to increased (when obstruction is detected) to resolve the contradiction between warm-up efficiency and flow path clearance
2Loss of energy
If the air stoichiometric ratio is set lower than normal operation to execute low-efficiency operation, then the thermal loss is increased for warm-up, but the dilution of pumping hydrogen becomes insufficient
Solution Approach 1:
The controller calculates the air concentration overvoltage as feedback to determine both the obstruction degree and the appropriate air flow rate adjustment, enabling dynamic control that prevents hydrogen concentration buildup while maintaining low-efficiency operation benefits
3Productivity
If the flow rate of air is reduced during low-efficiency operation, then the power generation efficiency is reduced, but the moisture discharge capability is insufficient
Solution Approach 1:
By continuously monitoring fuel cell voltage and air stoichiometric ratio to calculate air concentration overvoltage, the system detects obstruction conditions that would lead to degradation, and adjusts air flow rate accordingly to maintain reliability without sacrificing power generation efficiency unnecessarily
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 improves the stability of low-efficiency fuel cell operations by determining and mitigating air flow path obstructions, ensuring efficient hydrogen dilution and preventing fuel cell degradation, thus enhancing operational reliability.
Implementation Method 1
power is generated by an electrochemical reaction between hydrogen supplied to the fuel electrode and oxygen in the air supplied to the oxidant electrode
Implementation Method 2
the thermal loss (power generation loss) is increased
Data Source
AI summary
Provided is a fuel cell system including: a fuel cell which generates power by an electrochemical reaction between an oxidant gas supplied to an oxidant gas flow path and a fuel gas supplied to a fuel gas flow path; and a controller which adjusts an amount of the oxidant gas supplied to the fuel cell and a voltage of the fuel cell. The controller has an obstruction degree determining unit which determines a degree of obstruction of the oxidant gas flow path based on a stoichiometric ratio of the oxidant gas and the voltage of the fuel cell during a low-efficiency operation in which the stoichiometric ratio of the oxidant gas is reduced from the stoichiometric ratio of the oxidant gas during a normal operation and heat discharged from the fuel cell is increased from that during the normal operation. This improves stability of the low-efficiency operation of the fuel cell system.