Thermoelastic wires and generators for harvesting low grade waste heat (ThermoelasticHarvesting)

• Applicants: Professor Dr.-Ing. Jan Frenzel; Privatdozent Dr. Sebastian Fähler
• Subject Area: Synthesis and Properties of Functional Materials ; Thermodynamics and Kinetics as well as Properties of Phases and Microstructure of Materials
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 549600725

Climate change is one of the most pressing issues of our time. A direct, but often overlooked contribution to global warming is industrial waste heat. The maximum of heat is emitted below 80°C, and wasted, as no efficient heat to electricity conversion technology is available for this temperature range. We address this gap with a thermoelastic generator, which utilizes shape memory alloy wires as functional materials. These wires convert low-grade waste heat into mechanical energy, which then is converted to electrical energy by e.g. induction coils. We develop this emerging approach for harvesting low-grade waste heat within an interdisciplinary team. At RUB, shape memory wires with dedicated properties for thermoelastic harvesting are developed, and at HZRD, we integrate these wires within a thermoelastic generator to improve efficiency and electrical output power. With our complementary competence on material science, engineering and physics, we address the major scientific questions of this emerging approach. This includes maximizing of material and system efficiency, the interaction between functional material and device, and functional fatigue under realistic conditions. With respect to temperature and load cycles, this application of shape memory wires differs from all previous medical, actuation and elastocaloric applications and accordingly a new paradigm for material development is required. As key outcome, we expect a comprehensive understanding of thermoelastic energy harvesting, which is intimately connected with the shape memory wires used as functional materials. We aim to demonstrate, that our approach surpasses other harvesting technologies (e.g. thermoelectrics) in terms of conversion efficiency and specific power output.

• DFG Programme: Research Grants