How does the PEM (Fuel Cell) System Work?

1. PEM Ozone Generation System

The ways people get ozone artificially are divided into three categories, i.e. Air Discharge, Ultraviolet Light Radiation and Electro Analysis. Electro Analysis has two kinds :

1. Chemical Electrolysis Technology
2. Polymer Electrolyte Membrane (PEM) Ozone technology

PEM is the method that low-tension current connects anode and cathode of the special solid membrane to electrolyze water in order to separate hydrogen and oxygen.

The PEM technology system is made up of one or more electrodes surrounded by anode and cathode liquors, with special materials as dielectric substance dielectrics to produce ozone under low-tension high-density current. The PEM ozone generator which operates at constant pressures to produce a continuous flow of ozone in an oxygen stream having from 10% to 18% by weight of ozone. The ozone generator includes one or more electrolytic cells comprising an anode/anode flow field, a cathode/cathode flow field, and a proton exchange medium for maintaining the separation of ozone and oxygen from hydrogen. The ozone generator also has an anode reservoir which vents oxygen and ozone and a cathode reservoir which vents hydrogen. The anode reservoir can be filled from the cathode reservoir while continuing to produce ozone. The ozone generator is readily configured for self-control using a system controller programmed to operate the anode reservoir at a constant pressure.

PEM technology has some advantages, for example, it is easier to install and operate, safer, more longevous, more adaptable with high concentration and purity of ozone, than common technologies. There is one more superiority than air discharge systems, that it needs no predisposal equipments but only electricity and a small amount of pure water.

2. The Principle of PEM

The source used in PEM is only water, which can be decomposed into oxygen, ozone and hydrogen which can be exhausted into the air and the rest oxygen and ozone is completely safe. This method is the best up to now. It uses 3.5V low-tension DC voltage, which means that the wear on the anodes and cathodes is very low, thus ensuring a long life (the expected life time is longer than 15,000 hours).

The other technology used to manufacture Ozone is the air discharge technology which simulates a lightning strike, where dielectric substance dielectrics is placed parallelly between two parallel high-tension electrodes. Air which consists of oxygen (21%), hydrogen (78%) and other gases when subject to certain discharge period high-tension currents higher than 10000V are made to attack each other and the heat produced causes the oxygen to form Ozone. Some NOX nitrides are produced at the same time, which is internationally known as poisonous and can cause cancer. There is little possibility that high-purity ozone is made with air discharge technology because the amount of oxygen in the air is limited and the usage of high- tension current and wearable electrodes, restricts the useful life time and reduces the safety limits.

3. The PEM technical parameter of electrodes

Gas output quantity	3L / h /gm Ozone
Gas component	Oxygen & Ozone
Ozone concentration	18~20% (wt/wt)
Input power source	DC 0.4V-1.2A / cm2
Power consumption	-44W / gm Ozone
Pure water consumption	6ml / gm Ozone
Ambient temperature	4~35°C
Ambient moisture	less than 90%

4. The installation of PEM system

The electrodes used in PEM ozone generation system is mainly installed in ozone equipments producing ozone and ozone water.

The installation requirements of the equipments producing ozone

• Relevant accessories : Cathode Water Tank, Anode Water Tank, Connecting pipe, Special power source relay
• Other requirements : The Cathode Water Tank is made of inconductive and anticorrosive materials with good heat dissipation capacity; Anode Water Tank is made of inconductive materials with good heat dissipation and anti oxidation capacity; And connecting pipe should be made of ductile materials with good anti oxidation capacity and low thermal parameter.

The installation requirements of the equipment producing ozone water

• Relevant accessories : Pure water source, booster pump, multi channel pipes, connecting pipe, mixing equipment, special power source, relay
• Other requirements : Pure water source should adopt pure water, distilled water and anti osmotic equipments; Booster pump should adopt self suction pump with water outlet pressure higher than 4kg; Multi channel pipes should adopt stainless materials or UPVC standard service pipes; The diameter of connecting pipe is from 6mm to 8mm and made of ductile materials with good anti oxidation capacity and low thermal parameter.