hydrogen production from water using solar cells powered nafion ...

5. Place the cathode side GDL into the cathode graphite layer.
6. Cover the cathode GDL with 1mm thick silicon gasket.
7. Submerge the MEA into water and wait until the expansion of membrane stops
8. Insert the wet MEA on cathode GDL.
9. Place the anode side GDL on the anode side of the bipolar plate.
10. Cover the anode GDL with 1mm thick silicon gasket.
11. Place the bipolar plate with its mounted components on MEA.
12. Place the cathode GDL into the cathode side of the bipolar plate.
13. Go to step 6 (repeat this step equal to the “number of cells -1” in the stack)
14. Place the water inlet, hydrogen and oxygen outlet graphite plate.
15. Place the copper plate on anode graphite.
16. Place a silicon layer on copper plate.
17. Fixate the anode side end plate.
18. Insert the cap screws to the bolts and tighten them diagonally.
19. Stick the thermocouple probe on to graphite.
Multiple cell electrolyzers have smaller heat transfer area per active electrolysis
area with respect to single cell ones. Thus, the stack electrolyzers tend to get hotter than
single cell ones; especially at a low water flow and a high current density. Hot electrolysis
surfaces usually damage the membrane thus it should be avoided. To control the water inlet
temperature, water reservoir was placed in a constant temperature water bath.
Non-uniform water distribution, contact pressure differences between cells, clogged
passage ways may cause voltage and temperature gradient between cells or even the
melting of the membrane. So, the aim was to operate all the cells of the stack at the same
current, voltage and temperature. This requires proper water distribution and gas collecting
through all the cells of the stack. Applied current and water feed were kept the same as the
previous experimental sets but the occurred electrical potential or temperature of the cells
due to less heat transfer area were different. Deionized water was fed to the water inlet via
peristaltic pump until the water flooded from the oxygen output. The oxygen output was
connected to the inlet water reservoir to return the unreacted water. Hydrogen output line
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