Three segments distribution of gas diffusion layer porosity in a proton exchange membrane fuel cell

•A 3D, two-phase flow, non-isothermal agglomerate is established.•Averages of optimal porosity in three directions decrease with voltage increase.•The reaction rate is influenced by charge transfer near inlet region at low voltages.•The reaction rate is affected by reactant content near outlet region at middle voltages.•The porosity distributions along various directions can produce different effects.