Multi-parameter and multi-objective optimisation of thermoelectric modules for enhanced performance in geothermal passive generators

Geometrical optimisation studies of thermoelectric modules often overlook the significant influence of system-level components, particularly heat exchangers. This research addresses this critical gap by developing an integrated system-level optimisation approach, applied to a geothermal passive thermoelectric generator installed in Antarctica. The methodology is based on the premise that the thermal and electrical phenomena are interdependent, demanding a holistic design. For the first time, a comprehensive multi-objective, multi-parameter computational model for geometric optimisation of modules is presented, which incorporates all thermoelectric effects, temperature-dependent properties, and all system components. The framework simultaneously maximises electrical power output and minimises semiconductor material volume by adjusting the thermocouple length and cross-sectional area to their optimal values. Application to the Antarctic installation demonstrated that geometric optimisation yields energy production improvements from 3.7% to 12.6% with respect to the commercial modules used in the installation. These improvements correspond to configurations with leg lengths of 0.11 cm and 0.27 cm and cross-sectional areas of 0.023 cm 2 and 0.06 cm 2 , respectively. Crucially, an extended analysis revealed that while the source temperature difference does not affect optimal geometric parameters, the thermal resistances are paramount. Reducing the sum of heat exchanger thermal resistances by 26% increases optimisation potential by 60%, while also reducing semiconductor volume by 18.5%. These results demonstrate a system-level optimisation approach is essential. Findings indicate efforts must first prioritise optimising heat exchangers for the lowest thermal resistance. Subsequently, the optimal module geometry is determined by maximising the thermocouple cross-sectional area before adjusting the length for optimal thermal matching. • Experimentally validated computational model for thermoelectric generators. • Geometric optimisation of thermoelectric modules for a generator in Antarctica. • Enhancement of energy generation by up to 12.6% under real operating conditions. • Formulation of general design rules for thermoelectric generators below 100 °C.