Abstract: A PEM fuel cell power plant system (10) has a process air pump (26), which may be a fan, a blower or a compressor, with an adiabatic efficiency of between 40% and 70%. The process air at the inlet 27 of the cathode reactant gas flow field 16 is between 1.07 atmospheres and 1.85 atmospheres, and may be at an optimal pressure for maximum overall system efficiency P={0.45+2.6E?1.8E2} atms±0.2 atms where P is the air inlet pressure and E is the adiabatic efficiency of the process air pump.

Abstract: A PEM fuel cell power plant system (10) has a process air pump (26), which may be a fan, a blower or a compressor, with an adiabatic efficiency of between 40% and 70%. The process air at the inlet 27 of the cathode reactant gas flow field 16 is between 1.07 atmospheres and 1.

Abstract: A procedure for purging a fuel cell system at start-up or shutdown comprises directing the organic fuel, along with air, into a burner to produce a gas that is essentially inert to the fuel cell, such as a gas of nitrogen, carbon dioxide and water vapor. That inert gas is passed through either or both the fuel cell and fuel processing system components, such as a reformer and shift converter, to purge those components of undesirable gases. In the case of shutdown, after the cell has been disconnected from the primary load, the inert gas produced in the burner is passed either in series or in parallel through the fuel cell and fuel processing system.

Abstract: A PEM fuel cell power plant system (10) has a process air pump (26), which may be a fan, a blower or a compressor, with an adiabatic efficiency of between 40% and 70%. The process air at the inlet 27 of the cathode reactant gas flow field 16 is between 1.07 atmospheres and 1.

Abstract: A procedure for purging a fuel cell system at start-up or shutdown comprises directing the organic fuel, along with air, into a burner to produce a gas that is essentially inert to the fuel cell, such as a gas of nitrogen, carbon dioxide and water vapor. That inert gas is passed through either or both the fuel cell and fuel processing system components, such as a reformer and shift converter, to purge those components of undesirable gases. In the case of shutdown, after the cell has been disconnected from the primary load, the inert gas produced in the burner is passed either in series or in parallel through the fuel cell and fuel processing system.

Abstract: A simplified solid polymer electrolyte fuel cell power plant utilizes porous conductive separator plates having central passages which are filled with circulating coolant water. The coolant water passes through a heat exchanger which rejects heat generated in the power plant. Water appearing on the cathode side of each cell membrane is pumped into the water circulation passages through the porous oxidant reactant flow field plates by a positive .DELTA.P created between the cathode reactant flow field of each cell and the coolant water circulation passages between each cell. In order to create the desired .DELTA.P, at least one of the reactant gas streams will be referenced to the coolant water loop so as to create a coolant loop pressure which is less than the referenced reactant gas stream pressure. Excess water is removed from the coolant water stream. The system can operate at ambient or at elevated pressures.

Abstract: The incorporation of the hydrophilic porous element and the heat pipes in a fuel cell system enables high current density operation with a simplified accessory section as well as simplified controls, improved reliance and efficiency, and decreased maintenance and maintenance costs. The porous element, replacing the circulating pump and condenser of conventional systems, removes water from the cathode, wets the anode, and removes excess water from the system. The heat pipe system, replacing the coolant pump, coolant heat exchanger, and thermal and other controls, removes waste heat from the system.