Method and apparatus for establishing a negative pressure inside an enclosure that houses a fuel cell system

#The invention relates to a method and apparatus for establishing a negative pressure inside an enclosure that houses a fuel cell system.

#A fuel cell is an electrochemical device that converts chemical energy that is produced by a reaction directly into electrical energy. For example, one type of fuel cell includes a proton exchange membrane (PEM), often called a polymer electrolyte membrane, that permits only protons to pass between an anode and a cathode of the fuel cell. At the anode, diatomic hydrogen (a fuel) is reacted to produce hydrogen protons that pass through the PEM. The electrons produced by this reaction travel through circuitry that is external to the fuel cell to form an electrical current. At the cathode, oxygen is reduced and reacts with the hydrogen protons to form water. The anodic and cathodic reactions are described by the following equations:

#H2→2H++2e− at the anode of the cell, and

#FIG. 1 is a perspective view of a fuel cell system according to an embodiment of the invention.

#FIG. 2 is a front view of the fuel cell system of FIG. 1 according to an embodiment of the invention.

#FIG. 3 is a rear view of the fuel cell system of FIG. 1 according to an embodiment of the invention.

#Referring to FIG. 1, an embodiment 7 of a fuel cell system in accordance with the invention includes an enclosure, or cabinet 11. The cabinet 11 houses components of the fuel cell system 7, such as a blower 20. The blower 20 draws air from an interior region 18 of the cabinet 11 to establish an air flow that supplies oxygen (a reactant) to a fuel cell stack of the system 7. In this manner, the blower 20 and other components 19 (the fuel cell stack, a reformer, etc.) of the fuel cell system 7 are contained within the interior region 18 of the cabinet 11. A concern is that in some cases, the components 19 may leak a small amount of gas (hydrogen, as an example). However, because an air intake 22 of the blower 20 is positioned inside the cabinet 11 to draw air directly from the interior region 18, a negative pressure is established within the interior region 18 with respect to a exterior region 9 that generally surrounds the cabinet 11. As a result, any leaking gas is retained within the cabinet 11 and is drawn into the air flow path that extends through the fuel cell system 7. Thus, due to this arrangement, these gases may either be consumed by reactions in the fuel cell stack or oxidized by a tail gas oxidizer, another one of the components 19 of the fuel cell system 7.

#The negative cabinet pressure that is established by the above-described arrangement is to be contrasted with conventional arrangements that may establish a positive pressure inside the cabinet. This large positive pressure creates a large air flow out of the cabinet to dilute any stray gases to a safe concentration and to force the diluted stray gases outside of the cabinet. However, such a large outward air flow may reduce the temperature of the fuel cell system below an acceptable level and may even freeze the components of the fuel cell system.

#FIG. 2 depicts a front view of the fuel cell system 7 with a front panel 14 (see FIG. 1) of the cabinet 11 being removed. For purposes of filtering the air that is introduced into the air flow path of the fuel cell system 7, the system 7 includes a filter 16 (a high efficiency particulate arresting (HEPA) filter, for example) that is disposed in an opening 17 of the cabinet 11. Except for the flow of air that is created through the filter 16, the cabinet 11 is otherwise sealed from receiving air from outside of the cabinet 11, an arrangement that causes all air that enters the cabinet 11 to flow through the filter 16. In some embodiments, the filter 16 may be located in a rear panel 15 (see FIG. 3) of the cabinet 11 and may be located closer to the bottom than the top of the cabinet 11.