Question about the OCV of Fuel cell block example from ee lib

Dear all,

when I read the following example here https://de.mathworks.com/help/sps/ug/fuel-cell.html

In this example , the OCV was set as 65V, but the picture shows that when the h2 pressur the 5 bar with max h2 flow rate , result in a voltage on the resistor higher than 1100V. Why is that? even though the 10 Unit module series connected can only provide 650 V.

Besides: what about the fuel cell data in the m script, the Eoc is apprently for 1 Stack with 65 cells, what about tafel slope, is it also the data for a fuel cell stack or a singel cell? the same questions for all the other parameters. I can not find explaination in the Help documentation.

Thanks in advance if anyone has already some experiences regarding that ! Best regards!

%% Fuel Cell Parameters
Eoc = 65; % Open-circuit voltage [V]
A = 0.23; % Tafel slope [V]
Ri = 0.05; % Internal resistance [Ohm]
i0 = 80; % Nominal exchange current [A]
i_lim = 200; % Collapse current [A]
N_cell = 65; %Number of cells per module
number_unit = 10; %Module units (Series)
pH2_nom = 1.5e5; % Nominal H2 pressure [Pa]
pO2_nom = 1.0e5; % Nominal O2 pressure [Pa]
thermal_mass = 15000; % Thermal mass [J/K]
%vFC0 = 10; % Fuel Cell initial voltage [V]
Qfuel0 = 2.0; % Initial fuel flow rate [lpm]
Rload = 62.5;
pH2 = 2.5;
%V_init = 10;

Answer 1

[Sabin]

This behaviour is because we are changing the pressure of fuel from 2.5 to 5 bar. By increasing the pressure this will increase the Nernst voltage and the output voltage. When the amount of flow is very low or close to zero and the values of the fuel and air pressures are equal to their nominal values, the output voltage of the fuel cell is equal to the open-circuit voltage multiplied by the number of module units.

Look at the main equations in the doc page:

https://mathworks.com/help/sps/ref/fuelcell.html