The Critical Role of Hydrogen Diaphragm Fuel Cell Pumps
In the quest for sustainable energy solutions, diaphragm fuel cell pumps serve as a key component of hydrogen management in fuel cell systems, providing precise control, safety and efficiency.
As the world moves toward decarbonization, hydrogen fuel cells have emerged as a potential cornerstone technology for more sustainable energy generation. Within these systems, diaphragm fuel cell pumps perform several critical functions – from hydrogen recirculation to condensate management – that directly impact performance and longevity.
Powering the Future: How Hydrogen Fuel Cells Are Transforming Cities
The ways hydrogen-powered systems are being integrated into power grids, transportation networks and neighborhoods in South Korean cities such as Pyeongtaek and Namyangju are already demonstrating the potential of fuel cell technology today. In these cities, new large-scale residential and office buildings, for example, are required to be self-sufficient with sustainable energy solutions. Alongside renewable energy sources such as wind and solar power, fuel cells are an integral part of these initiatives. These systems typically generate up to 10 kW of power per module and can be connected in series to achieve higher outputs. They are particularly valuable for bridging power gaps when other energy sources do not provide sufficient output or during power outages.
At the heart of these systems are several different diaphragm fuel cell pumps that must meet a variety of unique challenges and the most stringent safety standards. The hydrogen used, for example, is challenging as it can form a highly explosive mixture with air and requires very little energy to ignite. Because of these characteristics, completely leak-tight systems are essential to prevent system failure or potential hazards. Since hydrogen's small molecular size furthermore makes it particularly prone to escape through even the smallest leak paths, high-quality materials and precise engineering are required to ensure reliable sealing and safe operation.
The Various Roles of Diaphragm Fuel Cell Pumps
If pure hydrogen is not directly available for use in fuel cells, it must first be extracted from a hydrogen carrier, such as natural gas or biomass. Pumps, such as KNF's N 938 diaphragm gas pump and a corresponding liquid pump like the KNF FM 50 or FP 25, play a crucial role in this production process.
For natural gas extraction, the process begins with steam methane reforming. In this step, a gas pump feeds natural gas into a reformer ① while a liquid pump feeds deionized ② water. Inside the reformer, the water is first heated to produce steam. This steam then reacts with the natural gas in a high-temperature catalytic reaction to produce a gas mixture containing hydrogen (H2) and carbon monoxide (CO). Because CO is highly toxic, flammable and can damage fuel cells, it enters a downstream preferential oxidation (PROX) unit where it is converted to carbon dioxide (CO2). After this conversion, the hydrogen can be further purified to meet the stringent quality requirements for use in fuel cell applications.
Once purified, the hydrogen flows into the fuel cell, where it undergoes an electrochemical reaction with oxygen to generate electricity, water and heat. At the anode, the hydrogen molecules are split into protons and electrons, creating an electric current that can be utilized to power a variety of applications. At the cathode, the protons, electrons, and oxygen combine to form water. This water must be effectively managed to prevent it from accumulating and potentially damaging the fuel cell components. In many systems, the water produced is simply removed by gravity, sometimes using impeller pumps. However, where active removal is required, KNF diaphragm pumps – such as a FF 12 or FP 7 liquid diaphragm pump ③ – can be a suitable solution, offering long service life and exceptional reliability.
Another application for diaphragm fuel cell pumps such as the N 938 mentioned above, is hydrogen recirculation within the fuel cell system. Any unreacted hydrogen is reused, ensuring maximum efficiency and minimizing waste ④. With a maximum flow rate of up to 60 l/min when used in a double-head configuration, it is ideal for efficient hydrogen handling. In addition, when customized as a hydrogen recirculation pump – such as by adding an anodized aluminum pump head – the N 938 can reliably handle wet gases. This capability is crucial for optimizing reaction conditions within the fuel cell. If required, it can also operate with positive inlet pressure generated by the fuel cell stack, providing greater flexibility for system integration and resulting in improved performance and efficiency.
Customizable Diaphragm Pumps Support the Transition to More Sustainable Energy
KNF diaphragm pumps can be extensively customized to meet the specific requirements of fuel cell systems. Their robust design makes them ideal for applications where reliability is essential. With a long service life and minimal to no maintenance, these diaphragm fuel cell pumps provide the reliability needed for critical applications in transportation, stationary power generation and industrial systems. As cities continue to evolve, and South Korea serves as a prime example of the successful integration of sustainable energy sources in urban environments, KNF gas and liquid diaphragm pumps will play an increasingly important role in the transition to cleaner energy solutions.
