Geometrical optimization of a thermoelectric device: Numerical simulations

•A geometrical optimisation of a thermoelectric (TE) device is performed.•Cubic and cylindrical thermocouples (TCs) have identical performances.•Several optimal ratios between the geometrical parameters of a TC exist.•The optimal ratios are independent of temperature and dimensions.•An increase in the number of TCs increases the power output of a TE device.