PEMFC inlet relative humidity and cell performance problem
 

I'm doing PEMFC simulation using ANSYS Fluent addon-module.
I finished validation with experimental data and I changed inlet relative humidity (from 100% to 50%).

As you know, Fluent can calculate the relative humidity of inlets (Volume weighted average>Species>Relative humidity). I calculated all the mass flow rate and mass fraction of reactants right. However, if I decrease relative humidity of inlet, the cell performance was increased.

I checked all the properties of PEMFC addon-moudle, but I could not found the reason.

Could you give me a tip to solve this problem?

best regards.

Thanks.