ABSTRACT
In an eort to decrease the dependence on fossil energy resources, renewable energy sources began to replace the combustion process. Geothermal resources, waste heat of cement plants, and oils heated via solar energy serve as renewable high-temperature heat reservoirs. Examples of low-temperature heat reservoirs are atmospheric air and seawater. A medium can be dened as heat reservoir, only if its temperature remains constant, independent of the amount of the heat transferred.
