You can simply use a couple of dc voltage sources to apply to both hot and cold side temperatures to the Peltier cell model supplied with Proteus. The temperature value is 1V x CelsiusDegree, so to apply 50°C to the hot side the generator will be set for 50V. As sketched here:
- Immagine 2023-12-20 171622.jpg (269.71 KiB) Viewed 799 times
Peltier cells are used here as power generators and are based, in this mode, on the Seeback effect (yes, like thermocouples are).
However, they are not at all efficient, in the specific case a single Peltier cell generates less than 1.5V at no load, while maintaining a temperature difference between the hot and cold side of 50°C. 4 cells (71 pairs, Imax=6A) at least are therefore needed to get sufficient voltage and current to turn a 6V mini-motor.
As someone has already said, the main problem is to keep the differential temperature between the two sides as wide as possible. Thermal solutions can be truly challenging; in order to transport the heat from the radiator to the hot side of the Peltier cells, as well as keeping the opposite side cold enough, an assembly consisting of metal plates and heat pipes can be used. The two sides must be thermally isolated from each other as much as possible.
The project file provides just an idea of both the basic schematic for the simulation (root sheet - sheet 1) and the thermal assembly (root sheet - Thermal Assembly Sketch). These are of course given just as start point to further development.