Abstract: A oxygen-production device includes a pulse-tube cryocooler for cooling air to liquefy oxygen, and a main container for obtaining and retaining liquefied oxygen. The main container has a heat regenerator, a cold head, and a pulse tube of the pulse-tube cryocooler therein. A temperature sensor measures a temperature of the liquefied oxygen, and a control device controls an output of the pulse-tube cryocooler according to the temperature measured by the temperature sensor.

Abstract: A oxygen-production device includes a pulse-tube cryocooler for cooling air to liquefy oxygen, and a main container for obtaining and retaining liquefied oxygen. The main container has a heat regenerator, a cold head, and a pulse tube of the pulse-tube cryocooler therein. A temperature sensor measures a temperature of the liquefied oxygen, and a control device controls an output of the pulse-tube cryocooler according to the temperature measured by the temperature sensor.

Abstract: A pulse tube cryocooler where conditions under which a difference in refrigeration output due to an installation posture can be reduced as compared with conventional pulse tube cryocoolers and where the refrigeration efficiency of the cryocooler is improved, and the refrigeration output can be raised. The pulse tube cryocooler may have a regenerator coupled to a compressor through a heat radiation part and an internal regenerating agent, with the compressor repeatedly feeding and suctioning a working gas, a pulse tube coupled to the regenerator through a cooling part, and a buffer tank coupled to the pulse tube through a heat radiation part and an inertance tube. A ratio of a space volume of the pulse tube to a space volume of the regenerator may be between 0.75 to 1.5. When a diameter of a circle having an area equal to an inner cross section of the regenerator is made an inner diameter, a value obtained by dividing a length of the regenerator by a square of the inner diameter may be between 0.11 to 0.26.

Abstract: A pulse tube cryocooler where conditions under which a difference in refrigeration output due to an installation posture can be reduced as compared with conventional pulse tube cryocoolers and where the refrigeration efficiency of the cryocooler is improved, and the refrigeration output can be raised. The pulse tube cryocooler may have a regenerator coupled to a compressor through a heat radiation part and an internal regenerating agent, with the compressor repeatedly feeding and suctioning a working gas, a pulse tube coupled to the regenerator through a cooling part, and a buffer tank coupled to the pulse tube through a heat radiation part and an inertance tube. A ratio of a space volume of the pulse tube to a space volume of the regenerator may be between 0.75 to 1.5. When a diameter of a circle having an area equal to an inner cross section of the regenerator is made an inner diameter, a value obtained by dividing a length of the regenerator by a square of the inner diameter may be between 0.11 to 0.26.

Abstract: When the operation of a fuel cell using phosphoric acid as an electrolyte is stopped, the concentration of phosphoric acid is decreased to thereby lower crystallization temperature of the electrolyte and at the same time reactive gas remaining inside the main body of the fuel cell is replaced by an inert gas.

Abstract: A fuel cell cooling device includes a plurality of plate-like fuel cell units arranged in a vertical stack and having singly interspersed therein cooling plates. A main coolant pipe supplies coolant at a pressure above the saturation point thereof to the cooling plates through corresponding inlet cooling pipes. A throttle is provided in each inlet cooling pipe to produce a pressure drop such that coolant entering a cooling plate is at a pressure below the saturation point thereof.

Abstract: A fuel cell system in which fuel gas is supplied from a fuel gas reformer to a fuel electrode, while oxidizing gas is supplied from the air blower to a oxidizer electrode. The fuel cell system generates electricity by the reaction gas's electrochemical reaction through the electrolyte. The fuel cell system has a fuel gas circulating pipe that connects the piping for the offgas coming from the fuel electrode to the fuel gas inlet pipe of the fuel electrode through the blower and valve. It has a discharge resistance that is connected to the electric output terminal of the fuel cell. When the operation of the fuel cell is stopped, the valve at the side of offgas coming from the fuel is closed, and the valve of the fuel gas circulation pipe is opened. The fuel gas remaining in the fuel cell system circulates through this pipe. The electric power that has generated at that time is discharged through the discharge resistance.

Abstract: A fuel cell stack is formed by a plurality of fuel cell blocks each of which comprises a plurality of fuel cell units laminated together. Each cell block has its own set of manifolds for supply and return of the reaction gases. Each manifold is insulated from the others and from the main gas line to which it is connected. When a cooling system is used, the various cooling elements are similarly electrically insulated from one another and from their main conduit.