In Figure 6.3, some of the water in the exit air is recovered for the water supply system. Assuming no water is carried out with the carbon dioxide on the anode side, what proportion of the water in the exit air must be recovered to maintain water balance?
Anode Negative O terminal
Positive Cathode terminal+
Active DMFC
Carbon dioxide out
Methanol and water mixture
Air and water vapor out
Water separator and store
Methanol sensor
Control valve for water resupply system
Methanol tank
Anode
Pump or control valve
Cathode
Pump
Electrolyte
-Air in
Figure 6.3: The main components of an 'active' DMFC system. Not all the components will always be present. Larger systems may have additional components, such as heat exchangers in the fuel system for cooling, air pumps, and methanol condensers in the CO outlet pipe. Note that the electrode connections are shown at the edge for simplicity; normally, the current will be taken off the whole face of the electrode, as in Figure 1.8, Chapter 1.
