The PEM Fuel Cell Unit, "EC5B", has been designed to allow the students to understand the fuel cells technology, especially that of a proton exchange membrane fuel cell (PEM). It also enables to calculate several fundamental parameters of a PEM type fuel cell, such as power density, polarization curves, efficiency, etc., and the variation of some of these parameters in function of the consumption of reagents and the developed power.
The "EC5B" unit is supplied with a stack of proton exchange membrane fuel cell (PEM) with a rated power of 100 W. The stack is composed of 24 cells with the shape of channeled plates that allow the air flow through the membrane. The membrane facilitates the hydrogen flow, generating the electrons release. There are separating plates which conduct electricity, allowing thus such electrons flow, between each pair of cells.
Cells are self-humidifying and do not require any type of external humidification.
The stack has an integrated fan able to provide the required air for good operation and to maintain the appropriate temperature.
Hydrogen storage represents one of the essential points regarding the hydrogen economy. For that purpose, a cylinder of metal hydride (300 NL) is included. Thanks to the absorption of the hydrogen inside, hydrogen is stored in a safe and certified way. Since the discharge pressure of the metal hydride cylinder is 15 – 20 bar, the "EC5B" unit includes two pressure regulators, one of them is prepared to be installed in the H2 cylinder in order to regulate the outlet pressure at 5 – 50 bar, the other is placed at the outlet of the metal hydride cylinder in order to regulate the inlet pressure to the stack in a range from 0.50 to 0.55 bar.
Two solenoid valves are included. One of them is located before the stack and controls the hydrogen inlet and when the unit is switched off, the valve is closed to avoid any possible hydrogen leakage. The other valve, placed at the stack outlet, purges the excess of water and hydrogen towards the exterior for a proper operation. A load regulation system enables the study of the generated electrical energy. It includes a variable power rheostat, which enables to vary the generated power.
A battery supplies 12 V to the unit electronic console.
The whole electrical circuit of the stack is protected by a short circuit unit in case of an over current (12 A) and low voltage shut down (12 V).
It includes a hydrogen leak detector with a detection range from 0 to 2% Vol. and from 0 to 100% L.E.L respectively.
The unit is supplied with the suitable sensors and instrumentation for the most representative parameters measurements and controls (electronic console).