Elementary and theoretical descriptions of fuel cells have been found in textbooks on thermodynamics for many years. Electrical energy or power is produced by a controlled chemical reaction. The fuel is oxidized at the anode, releasing electrons into the electric circuit. The oxidant is reduced at the cathode where electrons are collected. Reaction products can be found at the anode or the cathode, depending on the chemical reaction taking place. The circuit is completed by the movement of ions through the electrolyte. To maintain a suitable temperature in the cell, heat must either be supplied or removed.
There are several different kinds of fuel cells. The difference between them lies mainly in the electrolyte and temperature employed. Fuel cells can be constructed as sets of parallel plates (two electrode plates, an electrolyte plate and separation plates), tubes or monoliths. Several cells are combined to form a stack.
Many physical transport processes take place in fuel cells, for example, multicomponent flow, two-phase flow in some cases, electrochemical reactions, heat transfer and mass transport, as well as the generation of electricity.
Solid oxide fuel cells (SOFCs) and polymer-electrolyte membrane fuel cells (PEMFCs) are currently attracting a great deal of interest: SOFCs for electricity and heat production in stationary plants and as APUs (auxiliary power units), and PEMFCs for traction applications, e.g. in vehicles. There is also considerable interest in combining fuel cells with gas turbine systems.
At LTH both basic and applied research are being performed, as well as studies on integrated system level. Two research groups are active at the Department of Energy Sciences, namely in the divisions of Heat Transfer and Thermal Power Engineering. The divisions of Combustion Physics and Polymer Materials and Chemistry are also engaged in research connected with fuel cells.