This reaction device is provided with: a first flow path to which a fuel gas is supplied; a second flow path to which a gas containing oxygen is supplied; a hydrogen permeable membrane that partitions the first flow path from the second flow path, and that allows hydrogen contained in the fuel gas supplied to the first flow path to permeate toward the second flow path side; a catalyst that is provided in the second flow path and that accelerates an oxidation reaction between the oxygen and the hydrogen that has permeated through the hydrogen permeable membrane, wherein the hydrogen permeable membrane comprises a barium zirconate membrane.

A metal air battery includes a first battery cell module which generates electricity by oxidation of a metal and reduction of oxygen, a second battery cell module in fluid-communication with the first battery cell module and which generates electricity by oxidation of a metal and reduction of oxygen, and an air purifier in fluid-communication with the second battery cell module, where the air purifier purifies external air to supply first purified air to the second battery cell module, and the second battery cell module supplies second purified air generated by the oxidation of the metal and the reduction of the oxygen to the first battery cell module.

A method for humidifying a reactant in a fuel cell system is provided having a fuel cell stack, which is fluidically connected to a humidifier, wherein the humidifier comprises a membrane, on whose surface channels are formed. At least one of the channels is associated with a storage element for temporary storing of liquid water, the method involving the following steps: extracting the liquid water from the fuel cell stack and feeding the liquid water to the humidifier, admitting at least part of the liquid water into the storage element and temporarily storing the part therein, at least partially emptying the storage element by evaporating of the liquid water and humidifying of the reactant being supplied to the fuel cell stack by means of the evaporated liquid water, wherein the liquid water is extracted from the fuel cell stack both at the anode side and at the cathode side. A fuel cell system for carrying out the method is also provided.

A system and method of controlling water imbalance in an electrochemical cell is provided. The method includes determining a present water imbalance in the electrochemical cell by summing a water.sub.in and a water.sub.created less a water.sub.out. Water.sub.in represents an amount of water introduced into the electrochemical cell by an oxidant feed gas; water.sub.created represents an amount of water created by the electrochemical cell from the electrochemical reaction; and water.sub.out represents an amount of water discharged from the electrochemical cell by an oxidant exhaust gas. The method includes tracking a cumulative water imbalance during operation of the electrochemical cell by repeatedly determining the present water imbalance and continuing to sum the results during operation. And, the method also includes adjusting a flow rate of the oxidant feed gas entering the electrochemical cell based on the cumulative water imbalance.

A fuel cell system includes a mass flow rate measuring unit, an oxygen consumption mass flow rate acquiring unit, an exhaust-side air temperature acquiring unit, and an exhaust-side air humidity estimating unit. The mass flow rate measuring unit measures a first mass flow rate of intake-side air and a second mass flow rate of exhaust-side air. The oxygen consumption mass flow rate acquiring unit acquires a mass flow rate of oxygen consumption. The exhaust-side air humidity estimating unit estimate humidity in the exhaust-side air, on the basis of a difference between a flow rate of intake gas in the fuel cell system and a flow rate of exhaust gas from the fuel cell system, and the mass flow rate of the oxygen consumption.

A power system for an unmanned surface vehicle includes a fuel cell including a fuel cell stack, where the fuel cell stack includes a fuel inlet. The power system also includes a fuel storage including at least one fuel-storage module fluidly connected to the fuel inlet of the fuel cell stack. The fuel-storage module is a source of energy for the fuel cell. The power system also includes a fuel and thermal management system fluidly connected to the fuel inlet of the fuel cell stack. The fuel and thermal management system includes a heat exchanger in thermal communication with the fuel cell stack for removing waste heat produced by the fuel cell stack during operation. The fuel and thermal management system also includes a flow valve, a pressure regulator, and a conduit.

A power system for an unmanned surface vehicle is disclosed. In one embodiment, the power system includes a fuel cell, a fuel storage, and an air management system. The fuel cell includes a fuel cell stack. The fuel cell stack includes a fuel inlet, an air inlet, and an exhaust outlet. The fuel storage includes at least one fuel-storage module fluidly connected to the fuel inlet of the fuel cell stack. The fuel-storage module is a source of energy for the fuel cell. The air management system is fluidly connected to the air inlet and the exhaust outlet of the fuel cell. An air snorkel is part of the air management system and provides air to operate the fuel cell while the unmanned surface vehicle is deployed on a surface of a body of water. The air snorkel includes an intake and an exhaust.

A fuel cell exhaust device includes a pipe having one side open and the other side closed, a water tank having one side open and the other side closed, a reformer exhaust pipe communicating with the pipe between one side and the other side of the pipe, a stack exhaust pipe which is spaced apart from the reformer exhaust pipe and communicates with the pipe between one side and the other side of the pipe, a drain pipe positioned adjacent to the reformer exhaust pipe or the stack exhaust pipe and disposed on an outer circumferential surface of the water tank to communicate with the inside of the water tank, and a hole defined on the closed other side of the pipe and spaced apart from the closed other side of the water tank.

A fuel cell system includes a fuel cell stack, an anode system apparatus, a control unit, an anode outlet temperature sensor, and a purge valve. In a method of starting operation of the fuel cell system at low temperature, a control unit compares a predetermined freezing temperature threshold value with an anode outlet temperature detected by an anode outlet temperature sensor. Then, the control unit performs low temperature control to place the purge valve in the constantly open state in the case where the temperature is not higher than the freezing temperature threshold value, and performs normal control for switching opening/closing of the purge valve in the case where the temperature exceeds the freezing temperature threshold value.

A method for determining a humidity condition in a fuel cell system includes steps of: detecting an amount of water in a container that receives water discharged from a fuel cell stack, and determining a humidity condition in the fuel cell stack, based on the amount of water detected. As a result, the actual humidity condition in the fuel cell stack may be accurately determined even when humidification performance is degraded over operating time of the fuel cell system.