Daimler Ag

Daimler Chrysler Ag

Felix Blank

Ottmar Schmid

Cosimo Mazzotta

Cosmas Heller

Regina Wezel

Matthias Jesse

Thomas Kunick

Markus Schudy

Florian Finsterwalder

Martin Woehr

Verena Graf

Martin Quintus

Steffen Dehn

Martin WÖHR

Jörg Kleemann

A method for operating a fuel cell stack () for a fuel cell system, in particular of a vehicle, in which by reversing the flow direction () of a coolant during a cooling operation, the coolant in the fuel cell stack () is initially conveyed in a first direction (). The coolant is subsequently conveyed in a second direction () which is at least substantially opposite to the first direction (). A time period, after the elapse of which the flow direction () is reversed, is changed during the cooling operation. In addition, a distance at which a coolant volume is situated from a heat source () that is present in the fuel cell stack () may be changed during the cooling operation. The invention further relates to a fuel cell system.

Method for operating a fuel cell stack for a fuel cell system, and fuel cell system

The invention relates to a fuel cell having a membrane electrode arrangement () arranged between two separator plate units (), a first fluid area () for distribution of a first fluid which is adjacent to one side of the membrane-electrode arrangement (), a second fluid area () for distribution of a second fluid which is adjacent to a side of the membrane-electrode arrangement () opposite this side, with a separating wall () being arranged in at least one fluid area () and subdividing the fluid area () into at least one metering area () and one fluid subarea (), with the at least one metering area () having a fluid connection to the adjacent fluid subarea () at at least one metering point (), such that the first fluid can be metered from the metering area () through the metering point () into the adjacent fluid subarea (). According to the invention, starting from an input point (), at the edge, for the first fluid into the fluid area (), a cross section of the fluid subarea () increases in the flow direction () of the first fluid towards an output port ().

Separator plate unit with inclined separating wall having at least one metering point and fuel cell having separator plate unit thereof

The invention relates to a bipolar plate for a fuel cell stack, which comprises at least a an anode-side sub-plate. An interior of the bipolar plate is enclosed by the sub-plates, with a fluid port area arranged having at least one fluid port, over which a fluid can be conveyed to the fluid channels. The fluid channels are arranged on at least one of the flat sides, as well as a manifold zone, over which the fluid can be distributed to its assigned fluid channels and an accumulation zone, over which the fluid can be carried away from the fluid channels to another fluid port area. At least one of the sub-plates has a uniform arrangement of raised support points in the manifold zone and/or accumulation zone. Apart from the peripherally situated support points, a negative support point of the same type is designed adjacent to each raised support point inside the manifold zone and/or the accumulation zone.

Bipolar plate and fuel cell unit

A fuel cell includes a membrane electrode assembly (MEA) and at least one bipolar plate having an anode-side gas distributor structure for distributing anode reactants, a cathode-side gas distributor structure for distributing cathode reactants, and a guide passage structure for distributing a cooling medium. At least one of the anode-side gas distributor structure and the cathode-side gas distributor structure is divided into at least a first field and a second field, each of the first and second fields having an entry port and an exit port for the reactants. In addition, a method for such a fuel cell includes passing a reactant into an entry port of the first field and out of an exit port of the first field, mixing the reactant with a fresh reactant so as to form a mixture, and passing the mixture into the entry port of the second field.

Internally gas regulated fuel cell

A membrane electrode assembly for a fuel cell having a polymer electrolyte membrane, having a layer sequence comprising an ion-conducting membrane (), a catalyst layer () and a gas diffusion layer (). A substantially catalyst-free, porous condensation layer () is arranged between the catalyst layer () and the membrane ().

Membrane electrode assembly for a fuel cell

Proposed is a PEM fuel cell that comprises a separator plate assembly with a charging chamber, which is partitioned off by a partition wall and via charging spots has a fluid connection to an adjoining cathode chamber. The partition wall is designed so that the depths of the charging channels in the charging chamber and the depths of the distribution channels in the adjoining cathode chambers change in such a way that the quantity of oxidant that is charged at a charging spot from the charging chamber into the cathode chamber can be fixed in advance. As a result, the charging of oxidant, which has not been humidified or only slightly, into the cathode chamber can be improved with regard to the curve of the relative humidity along the cathode. Also proposed is a method for manufacturing a separator plate assembly suitable for a PEM fuel cell.

PEM fuel cell with charging chamber

An electrochemical fuel cell stack includes a membrane electrode assembly and a distributor plate. The distributor plate includes a channel region having gas channels for distributing reaction gas to the membrane electrode assembly, a first port area for supplying reaction gas to the channel region, and a second port area for removing reaction gas from the channel region. The gas channels are disentangled and each distributed in a respective separate channel area, at least one of the gas channels having at least one deflection point between the first and second port areas.

Electrochemical fuel cell stack

A passage structure for PEM fuel cells is configured locally differently in order to adapt the flow of gas on the membrane electrode assembly (MEA). Starting from the cathode entry port, the active gas volumetric flow per unit area on the MEA is locally varied by changing the number and/or cross section of the gas-carrying passages, so that the flow decreases toward the cathode exit port. Suitable configuration of the passage structure according to the invention allows the steam partial pressure to be optimally matched to the local conditions. The mass conversion is improved in these regions as a result without the electrolyte's drying out. At locations in the flowfield with a low gas humidity, the measures according to the invention (increased number of passages or passage width) significantly reduce the flow velocity. As a result, the transfer of water from the MEA to the gas flow is reduced and drying of the MEA is diminished.

Matching of the local area-specific gas flows in PEM fuel cells

A fuel cell stack for gaseous fuel includes a membrane electrode unit and a distribution plate including a channel area having gas channels for distributing the anode gas and the cathode gas to the membrane electrode unit and a port area for supplying the anode gas and the cathode gas into the channel area. Additional connecting channels discharge from the port areas along the gas channels so that unused anode gas or cathode gas is locally meterable from the port areas into the gas channels via these connecting channels.

Growing community of inventors

Constance, Germany

Felix Blank