Corrosion protection for a fuel cell coolant system
AssigneeUnited Technologies Corporation
InventorsRichard C. Nickols, Jr., John C. Trocciola
Life of this patent
Estimating the term…
Abstract
The internal coolant system of a fuel cell power plant utilizes a gas in the coolant fluid to inhibit the corrosion of those fuel cell components that corrode due to shunt currents flowing through the coolant fluid. In a preferred embodiment hydrogen gas is used.
Claims24
The combination of:
- a fuel cell stack having a positive end and a negative end and comprising a plurality of cells connected electrically in series, said stack including components defining coolant channels for carrying a coolant fluid into heat exchange relationship with said cells and a coolant manifold passage extending from the positive to the negative end of said stack for distributing a coolant fluid to said channels, said components comprising an oxidizable material and being in electrical communication with said fuel cells and connecting them in series electrically;
- and
- an ionically conductive coolant fluid within said manifold passage providing a path for shunt current from the positive to the negative end of said stack, said fluid including a gas mixed therein which oxidizes at the positive end of said stack at an electrochemical potential below which said material of said components at the positive end of said stack are oxidized for the level of shunt current through said fluid.
In combination:
- a fuel cell stack having a positive end and a negative end and comprising a plurality of fuel cells connected electrically in series and including an ionically conductive coolant fluid for removing heat from said stack said fluid providing a path for shunt currents from the positive to the negative end of said stack;
- and
- means for introducing an oxidizable gas into said coolant fluid, said stack including oxidizable material in contact with said coolant fluid at the positive end of said stack, said oxidizable gas adapted to oxidize at the positive end of said stack at an electrochemical potential below which said oxidizable material of said stack at the positive end thereof is oxidized for the level of shunt current through said fluid.
In a process of operating a fuel cell stack having a positive end and a negative end and comprising a plurality of fuel cells connected electrically in series, said stack including an ionically conductive coolant fluid for removing heat from said stack said fluid providing a shunt from the positive to the negative end of said stack wherein corrosion of fuel cell components at the positive end of the stack and in contact with said coolant fluid may occur due to the shunt currents flowing through said coolant fluid, the process of preventing the occurrence of said corrosion including:
- introducing an oxidizable gas into said coolant fluid wherein the gas is oxidized at the positive end of the stack in place of said corrosion.
Fuel cell apparatus for preventing corrosion due to shunt currents including, in combination:
- a fuel cell stack having a positive end and a negative end and comprising a plurality of fuel cells each including an electrolyte between a pair of electrodes, a separator plate sandwiched between adjacent fuel cells, and a separator plate at each end of said stack adjacent the end cells of said stack, said separator plates being in electrical communication with said fuel cells and connecting them in series electrically, a plurality of said separator plates having coolant channels therein for carrying a coolant fluid into heat exchange relationship with said fuel cells, said stack including at least one coolant fluid manifold passage extending from the positive end of said stack to the negative end of said stack for distributing coolant fluid to said coolant channels;
- means for introducing an ionically conductive coolant fluid into said manifold passage and in contact with said separator plates wherein shunt currents flow through said fluid from the positive to the negative end of said stack;
- and
- means for introducing an oxidizable gas into said coolant fluid, said plates comprising material in contact with said coolant fluid and oxidizable at the positive end of the stack at a potential higher than the potential at which said gas is oxidized for the particular level of shunt current flowing through said coolant fluid.
Dependencies are inferred from the claim text.