Solar Thermal Power Plants - Renewable Energy: Technology, Economics and Environment - page 206

For the technical realisation a compression piston is moved to the closed side,
so that the cold working gas flows to the warm space, passing through a regenera-
tor. The regenerator transmits the previously absorbed heat to the working gas
(isochorous heating phase (1); Fig. 5.22). The gas is warmed up to the tempera-
ture of the warm space while the regenerator cools down to the temperature of the
cold space. Subsequently, the working gas inside the warm space expands iso-
thermally and absorbs the heat from the warm space (isothermal expansion phase
(2); F ig. 5.22).

Isothermal expansion phase (2)

Isochorous heating phase (1)

Regenerator Regenerator

Cooler Cooler

Heater Heater

Worki n g
cylinder

Working
cylinder

Compress i on
cylinder

Compression
cylinder

Isothermal compression phase (4) Isochorous cooling phase (3)

Fig. 5.22 Working principle of a Stirling motor (see /5-24/)

The expanding working gas moves the working piston to the open side and per-
forms work. If the working piston passes the lower dead centre and is thus moved
to the closed side, the hot working gas is forced to pass the regenerator and to
move into the cold room. Heat is transferred isochorously from the working gas to
the regenerator (isochorous cooling phase (3); Fig. 5.22). The gas is cooled down
to the temperature of the cold space while the regenerator is warmed up to the
temperature of the warm space. The working gas is subsequently compressed
isothermally and transmits the generated heat to the cold space (isothermal com-
pression phase (4); Fig. 5.22).
The basic system components thus include the heated working cylinder, the
cooled compression cylinder and a regenerator which serves for intermediate en-
ergy storage. In most cases, the regenerator is a highly porous body of a high heat
capacity; this porous body has a considerably larger mass than the gas mass flow-