Multi-parameter matching optimization of cooling performance and thermal stress in variable cross-section thermoelectric legs

The design of variable cross-section thermoelectric legs has been identified as an effective approach to enhance the cooling performance of thermoelectric coolers (TECs) and mitigate thermal stress. However, investigations into the underlying mechanisms remain inadequate, lacking both depth and systematic analysis. Thermoelectric parameters are temperature-dependent, however, most existing studies either avoid analyzing these variable properties or demonstrate limited computational accuracy, while neglecting the different temperature distributions between P-type and N-type thermoelectric legs. Fourteen variable cross-section thermoelectric legs with distinct geometric parameters were constructed and investigated separately for P-type and N-type configurations based on variable properties. Mathematical models were developed to characterize the effects of geometric parameters on the Peltier effect, Joule heating effect, Fourier effect, and thermal stress. Temperature profiles and gradient functions along the leg height were derived from finite element simulations and subsequently incorporated into these models. Through this approach, qualitative and quantitative analyses were conducted to investigate the influence patterns and the underlying mechanisms of the geometric parameters on the Peltier effect, Joule heating effect, Fourier effect, and thermal stress of thermoelectric legs. The mechanism by which variable cross-section thermoelectric legs enhance the overall performance of thermoelectric coolers was elucidated in greater depth and with higher precision.