Flownex® is the software of choice in the design, analysis, and optimization of hydrogen technology. From water electrolysis to transient evaluations of fuel cells, Flownex® speeds up the design process and decreases the cost of development.


With pressure on industries to move to zero emissions, a strong focus has been put on the research and development of hydrogen applications for decarbonization. The European Union, and others for example, want to get to net-zero greenhouse gas emissions by 2050. One way of doing this is to implement technologies such as hydrogen fuel cells to generate electricity. Green Hydrogen, where renewable energy is used to generate hydrogen from water using a process called electrolysis, is one of the main sources of carbon free energy currently being researched.



Flownex® is used in the development and analysis of fuel cell systems. Flownex® allows for fast transients and the evaluation of system performance. Flownex® has several advantages in simulating fuel cells compared to other conventional software such as:

  • Fluid capabilities – Flownex® includes compressible gasses, two phase fluids, mixtures, etc. Custom fluids can be created or imported from NIST (National Institute of Standards and Technology).
  • Chemical reaction model for the fuel cell stack – Custom reactions can be implemented using scripting with languages such as C#, EES and Python. Integration with other software packages such as Cantera and Matlab and the ability to import reduced order models or ROMS using the Flownex® FMI capabilities.
  • Pumps and compressor models – simplified and complex models for pumps and compressors where pump charts and compressor maps can be included.
  • Discretised heat exchange models – finned tube heat exchangers, plate heat exchangers, etc.
  • Typical pressure drop models – pipes, valves, etc.
  • Steady state and transient solver – including an implicit transient solver allowing for large timesteps in long transients.
  • Control models for transient simulations – large library of analogue and digital controls.


Proper water management systems need to be implemented in the proton-exchange membrane fuel cell to insure for optimal performance. This results in several components being added to the air side of the fuel cell, increasing the complexities. Flownex® can be used in the design and development process of these complex systems. Flownex® is utilized for:

  • Detailed design of the humidifier in the water management system – scripts to implement water vapor transfer rates, user specified pressure drop components to apply pressure drop curves from literature, etc.
  • Determining the power requirement of the air side compressor.
  • Calculating the heating or cooling needed for the air stream to reach the fuel cell stack temperature.


The main loop and auxiliaries of a water electrolysis plant is a sensitive integrate system. The plant needs to be precisely controlled as the main driving force is the chemical process of water electrolysis. Also, high-temperatures and high-pressures further enhance the process but leads to the requirements of increased optimization in the operation of the plant. Flownex® can be used for:

  • Plant optimization
  • Analysis of system behaviour at critical modes
  • Sensor failure simulation
  • Cooling loops
  • Product design as per customer



Download our latest Hydrogen brochure or get in touch to discuss how Flownex can be applied in your Industry.

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