Evaluating the effectiveness of multi-layer fin structure on the performance and temperature uniformity of a thermoelectric generator system on a stationary diesel engine

Thermal uniformity and output power are two critical yet often conflicting performance characteristics of thermoelectric generator systems. This study proposes a multi-layer fin hot side heat exchanger to improve thermal uniformity while minimizing associated output power trade-offs. The influences of the fin-reduction step, r f , and the fin number in the last layer, N f,last , are investigated using a hybrid model combining computational fluid dynamics and thermal resistance calculations. The findings show that the multi-layer fin configuration reduces longitudinal heat conduction, intensifying temperature concentration in the front region of the heat exchanger. Increasing the r f suppresses this effect by redistributing the exhaust velocity and heat transfer area, enhancing the longitudinal temperature uniformity at the cost of reduced power. Meanwhile, increasing N f,last amplifies these effects, thereby improving the trade-off. The net output power improvement can reach 6.93%, while the improvement in thermal uniformity can be up to 90.43%. The cases N f,last = 34 & r f = 4 and N f,last = 34 & r f = 5 improve temperature uniformity while maintaining or increasing net output power. The proposed structure can improve the thermal uniformity by approximately 18% without sacrificing net output power and maintains a lower power reduction by 5–8% than the previously investigated trapezoidal fin and inclined muffler wall structures at comparable thermal uniformity levels. These findings demonstrate that the multi-layer fin structure is an effective approach for mitigating the trade-off between output power and thermal uniformity, contributing to the development of low-cost and efficient thermoelectric generator systems for internal combustion engines.