Fuel Cell Cathode Airflow Reversal for Membrane Humidification
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Solution Overview
Problem
Fuel cell systems require a humidification device in the cathode gas path, which occupies significant installation space and is costly.
Innovation Solution
Integrate an air compressor into the cathode gas path with branching main and secondary paths, allowing selective air supply to the fuel cell stack inlet or outlet, and reverse airflow for membrane humidification, eliminating the need for a humidification device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a humidification device is integrated into the cathode gas path, then the membranes are protected from drying out and damage, but the installation space requirement increases and the system cost increases
Solution Approach 1:
The fuel cell stack itself serves as the humidification device by reversing the airflow direction. Compressed air is supplied to the outlet side and flows backward through the stack, absorbing product water vapor from the cathode exhaust and using it to humidify the membranes, thereby eliminating the need for external humidification equipment
Solution Approach 2:
The fuel cell stack performs multiple functions: energy generation and self-humidification. By reversing the airflow direction, the stack simultaneously generates electricity and humidifies its own membranes, eliminating the need for separate humidification devices
2Reliability
If a humidification device is integrated into the cathode gas path, then the membranes are protected from drying out and damage, but the system cost increases
Solution Approach 1:
The fuel cell stack humidifies its own membranes by reversing airflow to absorb and utilize product water vapor generated during operation, eliminating the need for external humidification equipment and reducing system cost
Solution Approach 2:
The fuel cell stack performs dual functions of energy generation and self-humidification, reducing the need for additional components and lowering overall system cost
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
Simplifies the design, reduces space and cost by utilizing compressed air to humidify membranes, and enhances safety with movable shut-off elements.
Implementation Method 1
an air compressor (5), integrated into the cathode gas path (4)
Implementation Method 2
The air compressed by the air compressor is then supplied to the outlet (7) of the fuel cell stack. The air then leaves via the inlet (6) of the fuel cell stack again. In this way, the fuel cell stack (2) is traversed in reverse direction. The air carries product water with it
Data Source
Figure 1
Figure 2~4
Figure 5
AI summary
The invention relates to a fuel cell system (1) comprising a fuel cell stack (2) with a cathode (3), to which air can be fed as cathode gas via a cathode gas path (4), an air compressor (5) being integrated in the cathode gas path (4). According to the invention, the cathode gas path (4) branches downstream of the air compressor (5) into a main path (4.1), which can be connected to an inlet (6) of the fuel cell stack (2), and into a secondary path (4.2), which can be connected to an outlet (7) of the fuel cell stack (2), wherein the main path (4.1) and the secondary path (4.2) can each be shut off individually or together with the aid of a shut off device (8). The invention also relates to a method for operating a fuel cell system (1).