Fuel cell and hydrogen technologies

  Picture of a hydrogen trailer Copyright: © RWTH Aachen | CMP Figure 1: Hydrogen Trailer

Hydrogen infrastructure and testing applications

In order to ensure the experimental analysis of fuel cells a hydrogen combustion engines infrastructure was implemented at the Center for Mobile Propulsion, or CMP for short, providing the test benches with hydrogen. The continuous hydrogen supply is ensured by hydrogen trailers, see Figure. Up to two trailers can be connected to the distribution grid. This allows to execute long term tests. In addition to the currently availably hydrogen quality of 5.0, different hydrogen qualities can be composed from the gas storage. This application facilitates for the example the execution of filter tests for fuel cell applications.

  Experimental setup for the investigation of the fuel cell system in the test field of the CMP. Copyright: © RWTH Aachen | CMP Figure 2: Ballard fuel cell FCvelocity®-HD-7

The test field’s high-voltage infrastructure allows system powers of up to 250 kW. Therefore, also propulsion systems for heavy load applications like trucks or railway vehicles can be analyzed. This infrastructure is used, for example, in the current research project "X-EMU". In this project, a fuel cell hybrid drive for regional trains is being developed to be used on rails without overhead lines, see Figure 2. Additionally, the test benches can be connected to the battery garage with traction batteries, which allows the analysis of full-scale hybrid systems. Several test benches at the CMP can be coupled real-time capably to build up especially space-consuming test systems. Moreover, a climate chamber can be used to analyze the effects of different temperatures, for example cold start behavior.

Moreover, the TME has the possibility to test fuel cell stacks with an electric power of up to 30 kW on a dedicated test bench. The media temperatures, mass flows and pressures for air, hydrogen and coolant can be varied across a wide range. Additionally, the test bench is particularly designed for tests of balance-of-plant components such as intercoolers, humidifiers and hydrogen recirculation blowers – either as separate units or in arbitrary combinations with each other or with a stack. In this context, the integration of real-time simulation models is possible as well.

  Schematic representation of a fuel cell system with cell stack and peripheral components: air path, the hydrogen path and coolant loop. Copyright: © RWTH Aachen | CMP Figure 3 - Structure example for a PEM fuel cell system model

Simulative analyses

The experimental fuel cell development at the CMP is complemented by simulative analyses on system-, stack and cell level. This enables for example to parametrize and validate simulation models experimentally. At the same time, simulatively developed control strategies can be implemented on the test bench – “front loading”.

 
  Simulative investigation of fluid flows within a fuel cell. Shown are the coolant temperature within a single cell and the flow fields in the cell stack. Copyright: © RWTH Aachen | CMP Figure 4 - CFD-simulations - cell and stack -

For this purpose 0-1 D system models - Figure 3 -, 1-2 dimensional segmented component models and CFD-simulations - Figure 4 - are used.

The current research’s main focus lies on: water management, cold start behavior, cell degradation, prognostics and health management, optimization of the flow field, and operating strategy of fuel cells.