In principle, the collection of waste heat from industrial processes and energy plants – or to improve energy efficiency generally – makes good economic sense. But the apparatus required to do so is not straightforward: application-specific thermoelectric generators are needed for the direct conversion of heat flux to electricity using the well-documented Seebeck effect.

The modules, which are typically quite small (up to 5cm x 5cm²), first need to be characterised under conditions that are very close to the application, for example thermal cycling, and this is an expensive and time-consuming process. Scientists from the Fraunhofer Institute for Manufacturing Technology and Advanced Materials (IFAM) in Dresden have therefore built a novel test rig which can be used for the characterisation of thermoelectric modules under near-application conditions and temperatures of up to 600 degrees centigrade.

Previously, IFAM scientists had only been able to carry out investigations under steady-state conditions but the new rig has both a hot and a cold side which can be controlled and cycled independently of each other in terms of temperature – allowing for cyclical heat fluctuations to be simulated as they occur in industrial processes.

The new apparatus also enables the amount of energy generated to be determined under certain conditions, under different atmospheres, for example inert gas or vacuum, and allows for the thermal shock resistance of the materials to be tested. Amongst other things, the new test rig will support the wider adoption of thermoelectric generators in the German industry and a more circular approach to energy use.