6. Polygeneration

In the interests of rational energy use, there's no reason to stop at trithermal systems. As a result, more sophisticated systems exist that use more than three temperature levels. We'll mention just one here: trigeneration.

With a dither system, mechanical energy and medium-temperature heat can be generated from high-temperature heat. This medium-temperature heat can be recovered to operate a trithermal system. This coupling produces a quadrithermal system (figure 21 ):

• of heat is consumed at high temperatures at T _sc ;

• mechanical energy is produced;

• heat is generated at a first intermediate temperature T _...