Systems-level optimization of low-temperature thermoelectric waste heat recovery

The two limiting factors in effective thermoelectric (TE) waste heat recovery are TE conversion efficiency and effective heat exchange design. The following study motivated by recent encouraging results in materials and materials processing, which improves TE conversion efficiency, focuses on the second limiting factor of effective heat exchange design. A numerical model has been developed integrating TE modules into a cross-flow heat exchanger, similar to that of an automotive radiator. The heat exchanger aspects of this model were validated using manufacturer-provided data, while the TE aspects of the model were validated using a set of simple experiments. Using this validated numerical model, a systems-level optimization scheme was devised to determine the feasibility and potential of designing a cost-effective TE power generator using low temperature waste heat. Results show that crossflow heat exchangers with Bi₂Te₃ thermoelectrics can achieve net power densities over 90 W/liter.