15-12-2012, 06:32 PM
FUEL CELL
1FUEL CELL.ppt (Size: 2.35 MB / Downloads: 47)
Introduction
A fuel cell is an electrochemical energy conversion device.
It produces electricity from external supplies of fuel and oxidant.
These react in the presence of an electrolyte.
The reactants flow in and reaction products flow out while the electrolyte remains in the cell.
Fuel cells can operate virtually continuously as long as the necessary flows are maintained.
History
Sir William Robert Grove invented the first Fuel Cell in 1839.
Grove knew that water could be split into Hydrogen and Oxygen by sending electric current through it.
This process is called Electrolysis.
FUEL CELLS AND OTHER DEVICES
Fuel cell will compete with many other energy conversion devices.
Example:
I.C. Engines
Turbines
Batteries
Fuel Cell produce a D.C. Voltage that can be used to power motors.
Comparison With Batteries
Fuel cells consume reactant, which must be replenished from time to time, while batteries store electrical energy chemically in a closed system.
A fuel cell's electrodes are catalytic and relatively stable, while the electrodes within a battery react and change as a battery is charged or discharged.
SIZE
Fuel cell can be made in different range of sizes
They can be used to produce small amount of electric power for portable computers right up to very high power such as in power stations.
Proton exchange membrane fuel cell (PEMFC)
The Department of Energy (DOE) is focusing on the PEMFC as the most likely candidate for transportation applications.
The PEMFC has a high power density and a relatively low operating temperature ranging from 60 ºC to 80 ºC.
The low operating temperature means that it doesn't take very long for the fuel cell to warm up and begin generating electricity.
Solid oxide fuel cell (SOFC)
Longest operating life.
The high temperature also has an advantage: the steam produced by the fuel cell can be channeled into turbines to generate more electricity.
This process is called cogeneration of heat and power (CHP) and it improves the overall efficiency of the system.
Alkaline fuel cell (AFC)
This is one of the oldest designs for fuel cells.
The United States space program has used them since the 1960s.
The AFC is very susceptible to contamination, so it requires pure hydrogen and oxygen.
It is also very expensive, so this type of fuel cell is unlikely to be commercialized.