The Development of Skutterudite-Based Thermoelectric Generators for Vehicles

With the continuing improvements to thermoelectric (TE) materials and systems, their potential for both energy recovery and thermal management is increasingly apparent. Recent developments in materials and notably Skutterudites have allowed materials to be matched much more closely to the working temperatures of a light duty power-train. The choice of TE materials remains a substantial question in the design of a thermoelectric generator (TEG). While the quest for improvements in materials performance continues, the work reported in this paper is characterized by the decision to focus on the refinement of one class of TE materials: Skutterudites. In parallel, the engineering work on the integration of the TE materials into a heat exchanger could continue and be focused on the properties of this class of material. Skutterudites offer the combination of a high working temperature and a competitive electrical output (defined by ZT, the figure of merit). Well matched p-type and n-type skutterudites have been identified and built into modules that have in turn been integrated in an experimental TEG system. Transient engine tests based on legislative drive cycles have been run, exposing the materials to realistic practical conditions. The manufacturing of limited amounts of material in a research programme demands the use of engineering tools to support the prediction of whole system performance. In the reported work, the foundation of prediction is a dynamic model validated experimentally in high temperature transient conditions. The dynamic model is developed in a form that can be executed in real time. A TEG equipped with the limited samples available is operated under practical test conditions. Meanwhile the experimental data forms the boundary conditions for the real time model. Test results generated using a JLR I4 boosted GDI engine have formed the basis for a prediction of 414 W average output during the final phase of the WLTC cycle. The overall cycle average is 120 W which includes the low output initial phases of that cycle. The physical design of the TEG on which the prediction is based has overall dimensions, 450 mm (length) x 350 mm (width) x 120 mm (height) and has the potential to be engineered in different shapes according to requirements and physical constraints.