Fuel Cell Stack Air Distribution Diagnosis Using Dew Point Ratios
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Solution Overview
Problem
Existing fuel cell systems face challenges in accurately measuring and evenly distributing air flow rates to multiple fuel cell stacks, leading to performance deterioration and difficulty in implementing voltage control strategies due to the limitations of flow meters and moisture interference.
Innovation Solution
An apparatus and method using dew point meters and pressure sensors to determine air distribution performance by calculating absolute humidity and pressure ratios, enabling accurate assessment of air distribution between fuel cell stacks, and a controller to adjust airflow based on these measurements to prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If flow meters are used to measure air flow rates to fuel cell stacks, then air distribution can be monitored, but measurement accuracy decreases due to moisture interference and device complexity increases
Solution Approach 1:
The patent replaces mechanical flow meters with a measurement system based on thermodynamic parameters (temperature, pressure, humidity) and electrochemical calculations. Instead of mechanically measuring air flow, the system calculates flow rates by monitoring temperature changes, pressure variations, and humidity levels in the air supply lines to multiple fuel cell stacks, thereby eliminating moisture interference issues associated with mechanical flow meters
Solution Approach 2:
The patent introduces humidity sensors and temperature sensors as intermediary measurement devices that indirectly measure air flow characteristics. By measuring humidity and temperature changes in the air supply lines and using these as intermediate parameters, the system calculates air flow rates without direct mechanical contact with the air stream, avoiding the problems of direct flow meter measurement in humid environments
2Device complexity
If air is supplied to multiple fuel cell stacks from a single air compressor, then system complexity is reduced, but air distribution uniformity deteriorates
Solution Approach 1:
The patent implements a feedback control system that continuously monitors temperature, pressure, and humidity parameters in the air supply lines to multiple fuel cell stacks. Based on these measurements, the controller calculates air flow distribution and adjusts control valves or compressor operation to maintain uniform air distribution, thereby resolving the non-uniformity issue while keeping the single-compressor configuration
Solution Approach 2:
The patent changes the measurement parameters from direct flow rate measurement to indirect thermodynamic parameter monitoring (temperature, pressure, humidity). By monitoring these parameters and using electrochemical relationships to calculate flow distribution, the system achieves accurate air distribution monitoring and control without requiring complex flow measurement devices at each stack
3Measurement precision
If flow meters are installed to measure air flow rates, then air distribution can be measured, but installation space requirements increase and measurement reliability decreases
Solution Approach 1:
The patent replaces mechanical flow meters that are directly exposed to humid air with a sensor-based system measuring temperature, pressure, and humidity. These electrical sensors are less susceptible to moisture interference and can be protected more easily, thereby improving measurement reliability in the humid environment of fuel cell air supply systems
Solution Approach 2:
The patent uses relatively simple and inexpensive temperature, pressure, and humidity sensors instead of expensive and complex flow meters. These sensors are more reliable in humid environments and can be easily replaced if needed, providing a cost-effective and reliable measurement solution for air distribution monitoring
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 precise determination of air distribution performance and effective diagnosis of defects, improving airflow distribution and preventing flooding, thereby enhancing fuel cell system efficiency and durability.
Implementation Method 1
a first dew point meter (14) connected to the first air path (12) and configured to measure a dew point of the second air
Implementation Method 2
a first pressure sensor (16) connected to the first air path (12) and configured to measure pressure of the second air
Implementation Method 3
an air compressor for supplying air necessary for the electrochemical reaction in the fuel cell stack at appropriate flow rate and pressure
Data Source
AI summary
An apparatus and a method are for determining air distribution performance of a fuel cell system. The apparatus includes: an air cut off valve connected to a downstream side of an air compressor and supplied with first air discharged from the air compressor; a first fuel cell stack connected to the air cut off valve through a first air path and supplied with second air through the first air path; a second fuel cell stack connected to the air cut off valve through a second air path and supplied with third air through the second air path; and a controller. The controller determines a ratio between a flow rate of the third air and a flow rate of the second air based on absolute humidity values of the first, second, and the third air, and determines air distribution performance between the second fuel cell stack and the first fuel cell stack based on the ratio.