A first metal separator includes a seal bead protruding from a base plate. The seal bead includes a curved section having a curved shape in a plan view of the first metal separator. The combination of the radius of curvature and the angle of the curved section is set within a specific zone where variation in a seal surface pressure in a direction in which the seal bead extends is suppressed.

A fuel cell arrangement with a membrane electrode assembly is provided which comprises a cathode, an anode and a membrane arranged between the cathode and the anode, with an active area essentially predetermined by the membrane electrode assembly, and with a sealing structure laterally assigned to the membrane electrode assembly. The sealing structure comprises a sealing tongue extending into or over an edge region outside the active area for axially covering in a gas-tight manner a media channel formed in an adjacent bipolar plate and located in the edge region. A unit cell for a fuel cell stack with such a fuel cell arrangement is also provided.

A fuel cell arrangement with a membrane electrode assembly is provided which comprises a cathode, an anode and a membrane arranged between the cathode and the anode, with an active area essentially predetermined by the membrane electrode assembly, and with a sealing structure laterally assigned to the membrane electrode assembly. The sealing structure comprises a sealing tongue extending into or over an edge region outside the active area for axially covering in a gas-tight manner a media channel formed in an adjacent bipolar plate and located in the edge region. A unit cell for a fuel cell stack with such a fuel cell arrangement is also provided.

A separator is stacked on each of both surfaces of a membrane electrode assembly to form a fuel cell. This separator includes a base part extending in the form of a surface, and a bead continuous with the base part and protruding from the base part in a stacking direction. The bead includes, in plan view, a straight section extending straight and a curved section continuous with the straight section and curved from the straight section. In the separator, the height from the base part to a top part of the curved section is configured to be lower than the height from the base part to a top part of the straight section.

A separator is stacked on each of both surfaces of a membrane electrode assembly to form a fuel cell. This separator includes a base part extending in the form of a surface, and a bead continuous with the base part and protruding from the base part in a stacking direction. The bead includes, in plan view, a straight section extending straight and a curved section continuous with the straight section and curved from the straight section. In the separator, the height from the base part to a top part of the curved section is configured to be lower than the height from the base part to a top part of the straight section.

A gas liquid separator of a fuel cell system includes a first channel forming section forming a first channel for allowing an oxygen-containing exhaust gas to flow in a horizontal direction, and a second channel forming section forming a second channel connected to the first channel. The first channel forming section is provided with an inlet for guiding the oxygen-containing exhaust gas into the first channel. The second channel forming section is provided with an outlet for discharging the oxygen-containing exhaust gas flowing through the second channel. The second channel includes a bent channel for guiding upward the oxygen-containing exhaust gas guided from the first channel.

A gas liquid separator of a fuel cell system includes a first channel forming section forming a first channel for allowing an oxygen-containing exhaust gas to flow in a horizontal direction, and a second channel forming section forming a second channel connected to the first channel. The first channel forming section is provided with an inlet for guiding the oxygen-containing exhaust gas into the first channel. The second channel forming section is provided with an outlet for discharging the oxygen-containing exhaust gas flowing through the second channel. The second channel includes a bent channel for guiding upward the oxygen-containing exhaust gas guided from the first channel.

A four-fluid bipolar plate for a fuel cell includes a nonporous sub-plate comprising a first reactant half-plate joined to a second reactant half-plate. The nonporous sub-plate includes an internal coolant passage network having coolant flow field passages extending across an active area of the fuel cell. The nonporous sub-plate defines fuel supply and fuel return internal manifolds, oxidant supply and oxidant return internal manifolds, water management supply and water management return internal manifolds, and coolant supply and coolant return internal manifolds. The internal coolant passage network may have secondary cooling functions, such as a reactant coolant loop surrounding an internal reactant internal manifold, providing a heat exchange area to cool incoming reactant gas, and cooling the interfacial and porous sub-plate seals.

A four-fluid bipolar plate for a fuel cell includes a nonporous sub-plate comprising a first reactant half-plate joined to a second reactant half-plate. The nonporous sub-plate includes an internal coolant passage network having coolant flow field passages extending across an active area of the fuel cell. The nonporous sub-plate defines fuel supply and fuel return internal manifolds, oxidant supply and oxidant return internal manifolds, water management supply and water management return internal manifolds, and coolant supply and coolant return internal manifolds. The internal coolant passage network may have secondary cooling functions, such as a reactant coolant loop surrounding an internal reactant internal manifold, providing a heat exchange area to cool incoming reactant gas, and cooling the interfacial and porous sub-plate seals.

The invention relates to a bipolar plate (10) for a fuel cell (100), comprising—an internal coolant flow field (33), which comprises a coolant channel (43), and—a first and a second flat side (11, 12) with a first and second reactant flow field (31, 32) respectively, which has at least one first and second channel structure (41, 42) respectively, wherein—the first and the second channel structure (41, 42) each form a trunk channel (44) and branch channels (46), wherein the branch channels (46) branch off in a branching region (48) from the respective trunk channel (44), and a first intermediate region (51) is formed between the branch channels (46) of the first channel structure (31), and a second intermediate region (52) is formed between the branch channels (46) of the second channel structure (32), wherein normal projections of the first and second intermediate region (51, 52) onto a center plane (56) of the bipolar plate (10), which center plane is arranged between the two flat sides (11, 12) of the bipolar plate (10), partially overlap so that an overlapping region (53) is formed. It is provided that the coolant channel (43) extends from an outer region (54), which is located outside the first and second intermediate region (51, 52), into the overlapping region (53), crossing a transit region (55) in the process, wherein the transit region (55) is a subregion of the normal projection of the first intermediate region (51) onto the center plane, which projects from the overlapping region (53).