A thermal diode can be

• a heat engine which converts a heat difference directly into electric power.
• a heat engine working backwards as a refrigerator, usually a Peltier diode.
• a sensor device embedded on high power microprocessors used to monitor the temperature of the processor's die.

There are two types. One uses semiconductor, or less efficient metal, thermocouples, working on the principles of the Peltier-Seebeck effect. The other relies on vacuum tubes and the principles of thermionic emission.

External links

• A news article on the increases in semiconductor thermal diode efficiency
• Thermoelectric Power Generation: Converting Low-Grade Heat into Electricity (Equations for semiconductor thermal diodes)

Diodes