Understanding the Working Principles Behind PEM Fuel Cell Stacks

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PEM (Proton Exchange Membrane) fuel cells are a type of fuel cell that uses a Proton Exchange Membrane as the electrolyte. These fuel cells are widely used for various applications, including transportation and stationary power generation.
The working principles behind PEM fuel cell stacks involve several key components and processes:
1. Hydrogen Fuel Supply: The fuel cell stack requires a constant supply of hydrogen gas as fuel. The hydrogen can be obtained from various sources, including natural gas reforming, electrolysis of water, or by-product hydrogen from industrial processes.
2. Anode: Hydrogen gas is supplied to the anode (negative electrode) of the fuel cell stack. At the anode, the hydrogen molecules are split into protons (H+) and electrons (e^-) through a process called electrochemical oxidation. The catalyst, typically platinum, on the anode surface facilitates this reaction.
3. Proton Exchange Membrane: The protons generated at the anode pass through the Proton Exchange Membrane (PEM), a thin electrolyte membrane that selectively allows the movement of protons while blocking the passage of electrons. This membrane also prevents the mixing of fuel and oxidant gases.
4. Cathode: Oxygen gas (usually from the air) is supplied to the cathode (positive electrode) of the fuel cell stack. At the cathode, the oxygen reacts with the electrons from the external circuit and the protons that have passed through the PEM. This reaction forms water (H2O) as a by-product.
5. Electrical Circuit: The flow of electrons from the anode to the cathode creates an electrical current. This current can be harnessed for various applications, such as powering electronic devices or propelling a vehicle.
6. Heat and Water Management: The electrochemical reactions in the fuel cell stack generate heat and water vapor. Effective heat and water management systems are crucial to maintain optimal operating temperatures and prevent flooding of the PEM. This may involve the use of cooling systems and humidifiers.
Overall, PEM fuel cell stacks offer several advantages, including high power density, quick start-up and response times, and low emissions. However, challenges persist in terms of hydrogen infrastructure, cost, and durability. Researchers and engineers are continually working on improving the efficiency and reliability of PEM fuel cells to make them more viable for widespread use.

pem fuel cell stack