Abstract: A heating device includes a housing closed with a cover element and enclosing a combustion chamber, wherein an opening for receiving a burner device pointing into the combustion chamber is provided on the cover element, wherein the opening is delimited by a first cylindrical sheet section of the cover element (1), wherein the first sheet section is connected to a second sheet section of the cover element so as to face away from the combustion chamber. The second sheet section extends radially outwards as a contact flange for the burner device.

Abstract: A heating device, comprising includes a housing closed with a cover element and enclosing a combustion chamber, wherein an opening for receiving a burner device pointing into the combustion chamber is provided on the cover element, wherein the opening is delimited by a first cylindrical sheet section of the cover element, wherein the first sheet section is connected to a second sheet section of the cover element so as to face away from the combustion chamber. The second sheet section extends radially outwards as a contact flange for the burner device.

Abstract: A diffusion medium for use in a PEM fuel cell including a porous spacer layer disposed between a plurality of perforated layers having variable size and frequency of perforation patterns, each perforated layer having a microporous layer formed thereon, wherein the diffusion medium is adapted to optimize water management in and performance of the fuel cell.

Abstract: A diffusion medium for use in a PEM fuel cell including a porous spacer layer disposed between a plurality of perforated layers having variable size and frequency of perforation patterns, each perforated layer having a microporous layer formed thereon, wherein the diffusion medium is adapted to optimize water management in and performance of the fuel cell.

Abstract: A method for optimizing a fuel cell diffusion media having a spatially varying mass transport resistance is provided. The method includes at least two passes where a first-pass D/Deff profile for the fuel cell diffusion media is provided and applied to a computational model of the fuel cell having a baseline variable profile. At least one first-pass variable profile resulting from the application of the first-pass D/Deff profile to the computational mode is calculated and compared to a desired variable range. The first-pass D/Deff profile is refined, if necessary, to provide a second-pass D/Deff profile. A relative performance of the fuel cell with a second-pass variable profile resulting from an application of the second-pass D/Deff profile is determined. The second-pass D/Deff profile is refined, if necessary, until the second-pass variable profile has a desirable performance. An effective D/Deff profile is thereby provided.

Abstract: A gas diffusion layer for use in fuel cells comprises a fiber and non-fiber material in a ratio such that the water vapor diffusion transport resistance is greater than 0.8 s/cm measured at 80 C and 150 kPa absolute gas pressure when the gas diffusion layer has a thickness less than or equal to 300 microns. Another gas diffusion layer comprises a fiber and non-fiber material in a ratio such that the water vapor diffusion transport resistance is lower than 0.4 s/cm measured at 80 C and 150 kPa absolute gas pressure when the gas diffusion layer has a thickness greater than or equal to 100 microns. Fuel cells incorporating the gas diffusion layers are also provided.

Abstract: A gas diffusion layer for use in fuel cells includes a gas permeable diffusion structure and a microporous layer. The microporous layer incorporates a plurality of particles of anisotropic shape, simultaneously reducing the porosity of the microporous layer and increasing the tortuosity for gas transporting through the microporous layer. The anisotropic particles in the microporous layer are present in a first amount such that the gas diffusion layer has an increased gas transport resistance.

Abstract: A method for optimizing a fuel cell diffusion media having a spatially varying mass transport resistance is provided. The method includes at least two passes where a first-pass D/Deff profile for the fuel cell diffusion media is provided and applied to a computational model of the fuel cell having a baseline variable profile. At least one first-pass variable profile resulting from the application of the first-pass D/Deff profile to the computational mode is calculated and compared to a desired variable range. The first-pass D/Deff profile is refined, if necessary, to provide a second-pass D/Deff profile. A relative performance of the fuel cell with a second-pass variable profile resulting from an application of the second-pass D/Deff profile is determined. The second-pass D/Deff profile is refined, if necessary, until the second-pass variable profile has a desirable performance. An effective D/Deff profile is thereby provided.

Abstract: A fuel cell system is described having an active system for controlling local gas velocity in flow field channels by changing the gas channel cross sectional area depending on local relative humidity and state of water (i.e., vapor/liquid), thereby improving the removal of liquid water in a flow field channel. For example, a flow field channel is coated or otherwise provided with a material that swells in the presence of water vapor and/or liquid water, such as but not limited to super-absorbent materials. As the swelling continues, the channel gets narrower and the increased gas velocity leads to increased shear forces that improve the movement of the liquid water along the channel out of the cell. The water-uptake and swelling behavior is reversible and the channel will get wider as soon as the liquid is removed and/or the relative gas humidity is decreased.

Abstract: In order to improve a method for determining the substance conversion during areal electrochemical reactions in at least one local surface area between a counterelectrode arrangement of an areal design and an electrode arrangement of an areal design, which has a contact element segment designed in accordance with the surface area and a contact element contacting the remaining surface areas and being electrically insulated in relation to the contact element segment, in such a manner that the substance conversion can be determined in as simple a manner as possible it is suggested that not only the contact element but also the contact element segment be connected to one current source or current drain provided for carrying out the electrochemical reaction, that a current flowing between the contact element segment and the current source or current drain via a conductor generate a magnetic field around the conductor and that the magnetic field be determined as a measure for the substance conversion in the local s