Polymeric Materials (Institute for Technical Chemistry and Polymer Chemistry)

Entropy Wheel

The entropy-wheel: Energy recovery of industrial waste heat to increase the efficiency of power plants and thermal processes
Fig.1 Operating principle
Abb.2: Entropy wheel based on elastomers
Fig.3 Entropy wheel pulls a passenger car

State of the art, market potential

The production of energy causes a lot of unused waste heat. Therefore, an entropy wheel is a possibility to increase the effiency of power plants. There are several possible methods of using waste heat, but no one of them is usable for waste water with low temperature.

The actual state of the art of the entropy wheel and the possible market potential is summarized in a flyer available for download here.

Operating principle - origin of the name

The operating principle (see fig.1) is based on a special property of elastomers: Mechanical load causes stretching. In metals, bond gaps are increased, in elastomers coiled polymer chains are stretched. Therefore, no energy is changed during stretching, only the entropy causes the reacting forces.

Entropy wheel based on elastomers

For the generation of mechanical energy higher torques are required. Therefore, a reconstruction of the wheel and an optimization of the elastomers in use have been perfomerd over the last years. In addition, an alternative construction is using water streams is shown.

Entropy wheel based on shape-memory alloys

Comprehensive tests carried out on different materials enabled the development on an further improved entropy wheel: The usage of shape-memory alloys (SMA) creates more torque than the one of the actual available elastomers.
With the usage of springs made from Nitinol enough torque can be generated to pull a passender car.

Entropy wheel at the Hannover Messe Energy trade fair 2015

In Cooperation with the university of Bochum, the shape memory alloys where optimized. The latest entropy wheel based on this development has been presented at the Hannover Messe Energy trade fair in 2015.