Fuel Supply Module FSM

The other configuration allows H2 to flow fhrough the stack with the H2 exhaust valve open for most of the time this is called A flow-through operation. The H2 flow rate is higher than the stoichiometric ratio and is typically in the 

With a flow-through operation, water vapor and nitrogen also accumulate gradually within the anode, and periodic purging cannot be avoided. But the purging frequency is often much lower than that in the dead-ended operation. 

If the fuel is not H2 but a hydrocarbon-type fuel such as natural gas, propane, methanol, or ethanol, the FSM becomes very complicated. Briefly, the fuel needs to go through fuel processing in several steps, such as reforming, water-gas shift (WGS) reactions, and preferential oxidation to get a low CO content ( 10 ppm) H2-rich gas mixture called reformate, and the reformate is supplied to the stack. Some details are discussed in Chapter 4. 

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