3D Investigation of Tubular PEM Fuel Cell Performance Assuming Fluid- Solid- Heat Interaction

According to the declining trend of fossil fuel resources and the need to use renewable energies, appropriate research should be conducted for technical and functional studies in this regard. Therefore, in this research, a tubular PEM fuel  cell as a suitable energy source with three-dimensional geometry has been numerically simulated and investigated. For a comprehensive study, the equations of continuity, momentum, energy, stress-strain, and fluid-solid-heat interaction at steady state are defined, coupled together, and then solved by a finite element numerical code. Assuming the cell voltage changes from 0.95 to 0.4 volts, the passage of compressible fuel and air through the channels and porous media of the electrode and catalyst, and also about 6 degrees increase in the average cell temperature, causes approximately 35 nm displacement in different parts. These displacements, due to fluid-solid-heat interactions, cause thermal and mechanical stresses. The maximum stress is about 3500 kN/m2  in the electrolyte due to its displacement limit (average displacement 12.8 nm). Then the relation of voltage variation with current density, stress, fuel flow rate, displacement and fuel cell temperature was shown. Also the results showed that the assumption of fluid-solid-heat interaction reduces the fuel cell power density by about 3%. Finally, the effect of different parameters such as fuel and air channel radius, electronic and ionic conductivity were investigated. For example, at a voltage of 0.4 volt, 20 percent reduction in the radius of air or fuel channels, or 100 percent increase in the electron or ionic conductivity, increases the electrical current density by about 2.17, 0.05, 3.69, and 40 percent, respectively.