Abstract: The invention is a direct antifreeze solution concentration control system for a fuel cell power plant that controls a concentration of a direct antifreeze within a direct antifreeze solution cooling fluid within the plant. The concentration control system includes at least one fuel cell; a thermal management system that controls a temperature within the fuel cell including a porous water transport plate secured in direct fluid communication with a cathode catalyst of the fuel cell, wherein the direct antifreeze solution passes through the water transport plate; a water recovery device in fluid communication with a process exhaust stream exiting the fuel cell for recovering water from the process exhaust stream; and, a process exhaust by-pass line in fluid communication between the fuel cell and a plant exhaust vent that selectively directs some or all of the process exhaust stream to by-pass the water recovery device and to pass out of the plant through the plant exhaust vent.

Abstract: A direct antifreeze cooled fuel cell power plant system is disclosed for producing electrical energy from reducing and process oxidant fluid reactant streams. The system includes at least one fuel cell for producing electrical energy from the reducing and oxidant fluid streams; a thermal management system that directs flow of a cooling fluid for controlling temperature within the plant including a porous water transport plate adjacent and in direct fluid communication with a cathode catalyst of the fuel cell; a direct antifreeze solution passing through the water transport plate; and, fuel processing components secured in fluid communication with the thermal management system for processing a hydrocarbon fuel into the reducing fluid and for controlling a concentration of a direct antifreeze in the direct antifreeze solution.