**2. Mathematical Model**

In this fuel cell model, the real cell voltage *E*cell is estimated by subtracting the voltage losses inside the cell from the ideal cell voltage *ET*,*p*. These are summarized as activation *E*acti , ohmic *E*ohm and concentration *E*coni overpotentials [11]:

$$E\_{\rm cell} = E\_{T,p} - E\_{\rm act\_i} - E\_{\rm column} - E\_{\rm con\_i}.\tag{1}$$
