Abstract: A fuel cell coolant system for use with a plurality of fuel cell stacks connected electrically in series is adapted to use a non-dielectric coolant carried through each stack by electrically conductive tubes. Each stack also includes a plenum for distributing coolant to the tubes. To prevent short circuits across the stacks due to shunt currents in the coolant the plenums are electrically insulated from a grounded main coolant supply line, such as by dielectric hose connections, and each plenum is electrically connected to one end of its respective stack. By this invention the maximum driving potential for any shunt current is the potential drop across a stack rather than the potential drop from a stack to ground. In a preferred embodiment dielectric hoses are used to connect the plenums to the tubes in order to prevent short circuiting across cells within a stack.

Abstract: A cooler for removing waste heat from a stack of fuel cells includes a plurality of tubes for carrying the coolant through the stack. The tubes are disposed adjacent the nonelectrolyte side of electrodes in the stack in grooves or passageways formed in the surface of plates which separate one cell in the stack from another. Since the tubes are exposed to the electrolyte used in the stack they must be made from or at least include a protective coating of material which is stable in the electrolyte. Preferably this material is also a dielectric to prevent shunt currents from passing into the tubes and coolant which may be water.

Abstract: A fuel cell system includes an ejector for pumping steam and fuel into a steam reformer. Steam is the primary flow through the ejector and fuel is the secondary flow. The rate of steam flow is metered by a variable area orifice in the ejector. The fuel passes through a laminar restrictor in the conduit carrying the fuel to the ejector. A pressure regulator increases and decreases the pressure of the fuel supplied to the laminar restrictor by amounts equal to increases and decreases in the ejector back pressure thereby eliminating the ejector back pressure as a factor affecting the rate of fuel flow into the ejector. The laminar restrictor is designed to match the fuel flow to the ejector pumping characteristics so as to provide the desired steam to fuel ratio for the steam reformer for each operational mode of the fuel cell.

Abstract: Catalytic cracking of gaseous or distillate hydrocarbon fuels for the production of hydrogen (such as for use in a fuel cell) is provided in a push/pull operated dual chamber blow and run apparatus utilizing a catalytic bed employing ring catalyzed nickel supported on porous ceramic substrates, having a graduated catalyst content such that there is a low catalyst content in the portion of the bed near the inlet and a high catalyst content in the portion of the bed near the outlet.

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.