Principle of operation of phosphoric acid fuel cells pafcs 2.
Pafc fuel cell diagram.
It is one of the most mature cell types and the first to be used commercially.
Afc uses platinum electrode catalysts.
Phosphoric acid fuel cell pafc the phosphoric acid fuel cell has potential for use in small stationary power generation systems.
Most fuel cell systems that were sold before 2001 for the stationary power generation application used pafc technology.
Hydrogen is produced by diverting some of the reformed syngas to a hydrogen separator allowing the production of additional hydrogen via oversizing the reformer relative to the fuel cell.
Hence the net fuel cell reaction produces water as follows.
It operates at a higher temperature than polymer exchange membrane fuel cells so it has a longer warm up time.
The pafc is considered the first generation of modern fuel cells.
One of the major differences between the systems is that the pafc system has a separate reformer.
Cell structure the pafc itself consists of a pair of porous electrodes the fuel electrode and air electrode formed from mainly carbon material between which is placed an electrolyte.
The gas diffusion electrodes are composed of a porous substrate carbon or cloth facing the gas feed and a reactive catalyst layer consisting of platinized fine carbon powder facing.
H2 1 2 o2 h2o 4 figure 1.
This type of fuel cell is typically used for stationary power generation but some pafcs have been used to power large vehicles such as city buses.
Phosphoric acid fuel cells pafcs consist of an anode and a cathode made of a finely dispersed platinum catalyst on carbon and a silicon carbide structure that holds the phosphoric acid electrolyte.
Durability chp reference.
A phosphoric acid fuel cell pafc is composed of two porous gas diffusion electrodes namely cathode and anode juxtaposed against a porous electrolyte matrix.
They are quite resistant to poisoning by carbon monoxide but tend to have lower efficiency than other fuel cell types in producing electricity.
Based on a phosphoric acid fuel cell pafc system.
This makes it unsuitable for use in cars.
5 purecell fuel cell system alternate electrolyte property desired pafc operating temperature c 150 250 150 250 ionic conductivity mho cm 0 65 0 65 vapor pressure atm 0 4 5 x 10 7 175 c o 2 solubility mol cm3 high 1 x 10 7 175 c transference number 0 0 11 anion poisoning none phosphate poisons catalyst electrochemical stability no decomposition products.
