Assembly Thermal Stress Analysis

Analysis Type: thermal stress with multiple contact surfaces (FEA)
Objective: minimise end plate deformation at high temperature
Sector: distributed power generation

Client Benefits: Greater understanding of the effects of temperature rise on end plate stress and deformation, and a fast-track to design solutions.

Project Background: Fuel Cells have the potential to generate power more efficiently and with lower noise and emissions than conventional technology. Ceres Power Ltd is developing low cost and robust fuel cells that offer viable solutions for distributed power in the 1 to 25kWe range.

The heart of the fuel cell is the stack assembly, which comprises multiple-layers of metallic sheets and gaskets to form complex and precise gas passages. The stack operates at relatively high temperature and requires a large clamping force to contain the stack layers and achieve adequate sealing. Key components to achieving optimum performance are therefore the stack end plates.

Ceres Power wanted to modify the end plate design in order to optimise material choice and minimise plate deflection. To avoid the time, uncertainty and cost of a make-and-test approach they engaged TriVista Engineering to carry out a stress and deformation study of the existing design, and to make design recommendations based on the results.

Solution: A 3D FEA model was built from existing CAD data. The large number of layers in the stack made good use of the powerful contact element capabilities of ANSYS®. Geometric symmetry was also used to reduce the model size and achieve faster solution times. Comprehensive stress and deformation data was derived for a range of temperature conditions.

The project delivered a virtual design tool, which provided valuable insight into the causes and extent of end plate deformation. Further analysis was later carried out to confirm the beneficial impact of the design countermeasures.

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