Abstract: Thermoelectric effect is the most efficient way to convert electricity energy directly from the temperature gradient, and the three most promising energy technologies in the 21st century with solar photovoltaic technology and fuel cells. Thermoelectric effect based power generation, cooling and heating devices are solid state, environmentally friendly, reliablee, long life, easy to maintain, easy to achieve miniaturization and integration. So they have unparalleled advantages in the aerospace, vehicle industrial, waste heat recovery, electronic cooling and other fields comparing with conventional energy devices. The working principle, construction characteristics, and application fields of thermoelectric devices are introduced. The thermodynamic studies for thermoelectric generators, thermoelectric refrigerators and thermoelectric heat pumps are reviewed from non-equilibrium thermodynamics and finite time thermodynamics two aspects. The research based on finite time thermodynamics is summarized systematically. The developing directions of thermoelectric devices in the future such as the development of thermoelectric generators heat source, multi-stage thermoelectric devices, combined thermoelectric devices, thermoelectric device heat transfer enhancement are previewed.

Key words: Finite time thermodynamics, Thermoelectric generator, Thermoelectric heat pump, Thermoelectric refrigerator, Energy assessment, Inherent energy efficiency, Machine tools, Virtual workpiece