Water content estimation apparatus for fuel cell and fuel cell system

A water content estimation apparatus for a fuel cell which estimates a water content of a fuel cell including a single cell, the single cell having an anode electrode, a cathode electrode, an electrolyte membrane existing between the anode electrode and the cathode electrode, and reactant gas flow channels, including a fuel gas flow channel for supplying fuel gas to the anode electrode and an oxidation gas flow channel for supplying oxidation gas to the cathode electrode, the water content estimation apparatus for a fuel cell comprising:

• an estimating unit for estimating a residual water content distribution in at least one of the reactant gas flow channels and a moisture content distribution in the electrolyte membrane in a cell plane of the single cell while taking into consideration water transfer that occurs between the anode electrode and the cathode electrode via the electrolyte membrane,
• wherein the estimating unit is programmed to calculate a rate of water transfer via the electrolyte membrane between the anode electrode and the cathode electrode based on a difference in water vapor partial pressure between the anode electrode-side and the cathode electrode-side, and to estimate a residual water content distribution and a moisture content distribution based on the calculated water transfer rate.