Transient energy, exergy, and economic analysis of an automotive thermoelectric generator with different structures

In this study, to investigate the dynamic characteristics of automotive thermoelectric generators (ATEGs), a detailed transient energy, exergy, and economics analysis is conducted for a novel ATEG with heat pipes and a traditional ATEG for the first time. Moreover, this study provides a comprehensive analysis of the discrepancies between the results derived from the steady-state model and the transient model. To achieve this objective, a transient CFD and thermal-electric hybrid numerical model is established to accurately predict the transient characteristics of the ATEG. Results indicate that the novel ATEG achieves average improvements of 60.99 % in output voltage and 32.98 % in output power over the traditional ATEG during a complete driving cycle. Additionally, the steady-state model overestimates the performance of the ATEG. The exergy efficiency is minimally impacted by the use of heat pipes and fluctuations in transient exhaust heat, consistently remaining around 19 % for both ATEGs. In a single driving cycle, the novel and traditional ATEGs generate 0.0442 kWh and 0.0307 kWh of electricity, respectively. The cost payback periods are 2.86 years for the novel ATEG and 1.83 years for the traditional ATEG, and it is found that using steady-state models for economic analysis may underestimate the cost payback period. This study successfully bridges the research gap in energy, exergy, and economic analyses under transient conditions, offering valuable insights into the dynamic properties of ATEGs.