Abstract: The invention concerns fuel cell systems and methods for converting chemical energy of a fuel containing hydrogen into electricity. According to the invention, a fuel cell stack is provided having at least one anode and one cathode separated by a proton-exchange membrane. A fuel transport circuit feeds fuel to the fuel cell stack, and a temperature control system is adapted to control the temperature of the fuel cell stack by circulating a coolant medium through said fuel cell stack. The temperature control system includes a pump for circulating the coolant medium, a heater unit connected to a coolant transport circuit for heating the coolant with a PTC heater, a heat radiation unit connected to the coolant transport circuit for removing excess heat, and a temperature sensor.

Abstract: The present invention concerns a system and a fuel ejector for controlling the fuel flow in proton exchange membrane fuel cells. The ejector comprises a nozzle receiving pressurized fuel from a first inlet into said ejector and including a first tapered section narrowing towards the outlet end of said nozzle in order to provide a flow of fuel, a second inlet for receiving recirculated fuel from a proton exchange membrane fuel cell, a diffuser comprising at least a second tapered section receiving fuel from said nozzle and said second inlet, and an outlet for delivering fuel from said diffuser to the anode system of said proton exchange membrane fuel cell. A shaped elongate rod having a butt end and an opposite pointed is movable lengthwise along its axis to engage with said first tapered section in order to provide a fuel flow control means for the fuel at the outlet of said nozzle.

Abstract: The invention concerns fuel cell systems and methods for converting chemical energy of a fuel containing hydrogen into electricity. According to the invention, a fuel cell stack is provided having at least one anode and one cathode separated by a proton-exchange membrane. A fuel transport circuit feeds fuel to the fuel cell stack, and a temperature control system is adapted to control the temperature of the fuel cell stack by circulating a coolant medium through said fuel cell stack. The temperature control system includes a pump for circulating the coolant medium, a heater unit connected to a coolant transport circuit for heating the coolant with a PTC heater, a heat radiation unit connected to the coolant transport circuit for removing excess heat, and a temperature sensor.