Hydrogen pump cells

Hydrogen pumping cells can constitute either a module on their own or a portion of a ftiel cell stack. The power needed for hydrogen pumping can be supplied by the ftiel cell stack. 

The general behavior of the membrane with cation contamination, with and without the water effects, is presented and discussed based on predictions from the model. The model is extended to include the potential from the metal on each side into and through the ionomer in the electrodes. Because the work is focused on the membrane, this aspect is restricted to only include a hydrogen pump cell with hydrogen electrodes on both the anode and cathode sides. 

Hydrogen pump cells, where hydrogen oxidizes at the anode and reduces back to hydrogen at the cathode, were also utilized to better imderstand the nature of performance loss due to cationic contamination. The results of the hydrogen pump also showed a limiting current under contaminated conditions, a phenomenon not known for fully protonated systems [11]. This indicates that a mechanism of proton limitation exists in contaminated cases. 

Petek T, Wainright J, Savinell R (2012) High temperature electrochemical hydrogen pump cell using a PBl membrane at high current densities. ECS Trans 50 2153-2162... 

Three kinds of equilibrium potentials are distinguishable. A metal-ion potential exists if a metal and its ions are present in balanced phases, e.g., zinc and zinc ions at the anode of the Daniell element. A redox potential can be found if both phases exchange electrons and the electron exchange is in equilibrium for example, the normal hydrogen half-cell with an electron transfer between hydrogen and protons at the platinum electrode. In the case where a couple of different ions are present, of which only one can cross the phase boundary — a situation which may exist at a semiperme-able membrane — one obtains a so called membrane potential. Well-known examples are the sodium/potassium ion pumps in human cells. 

A CW tunable dye laser (Stilbene 3) is pumped by the ultraviolet lines of an argon ion laser. The laser is focused in a cell filled with a mixture of cesium and hydrogen. The cell (10 cm long with an inside radius of 2.6 cm) is connected to a reservoir containing liquid cesium and to a pumping system or a hydrogen gas tank. It is placed in an oven heated independently from the reservoir. The laser beam enters the cell from below through a flat window and is focused at a point 1 cm above the window. 

Finally the possibility to utilize electrolysers to elevate hydrogen pressure and recirculate it inside anode flow fields in H2FCS power sources has been recently considered [10]. This electro-chemical approach for hydrogen pumping could be effected with an external additional smaller PEMFC component, connected to the stack devoted to electric power generation, or alternatively using in electrolysis mode a group of cells of the main PEMFC stack. 

Barbir F, Gorgun H (2007) Electrochemical hydrogen pump for recirculation of hydrogen in a fuel cell stack. J Appl Electrochem 37 359-365... 

Figure 11.33. Hydrogen pumping I-V curves obtained from a H3PO4 fuel cell. T = 160 °C Reformate contains 1% CO and 29% H2, balanced by CO2 and N2.

He et al. discovered that hydrogen pumping can shorten the fuel cell incubation time and lead to higher performance [17]. During their experiment, hydrogen was... 

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