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Abstract
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Chlor- alkali electrolysis (CA) is used to produce chlorine, hydrogen gas and caustic soda with
high purity (>99.999%). Nevertheless, this electrochemical process consumes a large amount of
electrical energy. The three primary electrolytic processes for producing products are the
diaphragm cell process, the mercury cell process, and the membrane cell process. In membrane
process, elements such as cell components and the arrangement of components in the cell are
decisive factors in the amount of energy consumption, which is investigated in this study [1]. The
purpose of this study is to investigate to incorporate some configuration strategies to mitigate the
energy consumption of the cell and as a result increase the efficiency simultaneously. To avoid the
drastic problems for three-chamber electrolyzers (standard design), a design called zero- gap
configuration has been considered which is adapted from fuel cell technology. In a zero-gap cell,
the cathode is in close contact with the ion exchange membrane. Water or oxygen is fed into the
cell chamber and caustic soda is collected from it. Electrolysis cells that contain ion selective
membranes are manufactured in three basic designs: gap cell, solid polymer electrolyte (SPE) and
zero-gap cell. Zero-gap electrolysis was first proposed in 1967 by Costa et al. using electrodes on
both sides of an ion exchange membrane. New cell designs including the use of porous electrodes
and the use of fuel cell electrodes that are placed directly on the membrane have been studied. In
the chlor-alkali process, the zero-gap cell design works by compressing two porous electrodes
(mainly based on mesh and nickel foam) on both sides of a sodium ion exchange membrane, which
eliminates the gap between the two electrodes compared to the standard arrangement, so It
significantly reduces the contribution of the ohmic resistance of the electrolyte between the two
electrodes. Chloral-alkali process cells are used in both advanced and normal wa
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