Apparatus for regulating pressure of exhaust gas of fuel cell system

An apparatus for regulating pressure of exhaust gas of a fuel cell system, the apparatus comprising:

• porous foam mounted in an exhaust tube and having a structure in a mesh foam with a plurality of pores therein;
• a regulator configured to compress or expand the porous foam to regulate a differential pressure of exhaust gas flowing through the exhaust tube;
• and
• a first support part configured to fix one end of the porous foam to an inner circumferential surface of the exhaust tube, wherein the first support part has a shape extending toward a central portion of the exhaust tube from the inner circumferential surface of the exhaust tube and is configured to suppress the one end of the porous foam from being deformed by exhaust gas flow,
• wherein the one end of the porous foam is fixed to the exhaust tube and an opposite end of the porous foam is coupled to the regulator with respect to a flow direction of the exhaust gas in the exhaust tube,
• wherein a length of the porous foam in the flow direction of the exhaust gas is increased or decreased as the opposite end of the porous foam is moved by the regulator,
• wherein the regulator is disposed outer side of the plurality of pores in a direction perpendicular to the flow direction of the exhaust gas,
• wherein the regulator compresses or expands the porous foam to vary porosity of the porous foam, and flow resistance to which the exhaust gas is subjected while passing through the porous foam varies as the porosity of the porous foam varies so that the differential pressure of the exhaust gas flowing through the exhaust tube is regulated, and
• wherein the porosity is given by:
• ϕ
• =
• V
• V
• V
• S
• +
• V
• V
• where ϕ is the porosity, VS is a total volume of a material portion of the porous foam, and VV is a total volume of the pores in the porous foam.