Technological evaluation of printed, large surface thermoelectric generators for waste heat recuperation: design, simulation and optimization

Franke, Leonard
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"In future, there will be an increasing demand for waste heat recovery systems (WHRS). So far current technologies are not expected to fulfill the requirement expected for a broad deployment. Thermoelectric generators (TEGs) for the direct transformation from heat to electricity represent hereby a promising alternative. Novel printed TEGs based on organic and inorganic materials (OTEGs) will be brought to market maturity soon. The usage of new cost-efficient materials and the targeted automation as well as the scalability of the production process offer a considerable cost reduction compared to conventional TEGs, making this technology interesting for the recovery of large amounts of waste heat. Moreover, the used materials are environmentally compliant. For first time, a WHRS based on a simple plate heat exchanger design equipped with this new generation of TEGs was evaluated from a technological point of view. For this the thermal behavior of the system was simulated using the Simulink modelling environment and at the same time a fluid dynamical examination of the heat exchanger channels was conducted to determine the dissipated energy by the fluids in the heat exchanger using OpenFOAM. To determine the optimal operational conditions of the system the elaborated models where used. The models demonstrated that current generator efficiencies of ZT 0.1 could deliver next to the auxiliary energy also a surplus power of approximately 250 W compared to a heat power transferred of 39.44 kW. For future TEGs with an efficiency of ZT 0.5 an increase to 1.2 kW was determined by the models which is equivalent to a net system efficiency close to 2.5 %. The waste heat was bundled prior in a thermal oil cycle with a temperature of 230 °C while for the cooling cycle water at 15 °C was assumed".