Which device is specifically designed to convert thermal energy into electrical energy?

The thermocouple is specifically designed to convert thermal energy into electrical energy. It operates based on the principle of the Seebeck effect, where two dissimilar metals are joined at two junctions. When there is a temperature difference between these junctions, a voltage is produced that can be measured and used to generate electrical energy. This property makes thermocouples valuable in various applications, such as temperature measurement and control, as well as in power generation systems where waste heat can be converted into usable electric power.

In contrast, the linear variable differential transformer is primarily a sensor used to measure linear displacement, adjusting the electrical output based on a change in position rather than converting thermal energy. A gas recirculation fan is utilized to move air within a system, often aiding in cooling or ventilation processes but not converting thermal energy itself into electricity. Finally, a coal breaker is a device used in the processing of coal, mechanically breaking down larger pieces; it does not convert energy types but facilitates the handling of fuel for combustion processes.