**5. Conclusions**

Thermoelectric technology has evolved significantly in the last decade, fundamentally due to the improvement of thermoelectric materials, which boosted the commercialization of novel applications in the civil market. However, efficiencies of thermoelectric devices that provide heating, cooling and generation of electric power are still low. In this sense, the scientific community considers essential the optimization of heat exchangers that must be mounted at either end of the Peltier modules.

This chapter has shown the major influence of the heat exchangers on the efficiency of thermoelectric devices, and indicates that this efficiency rises as the thermal resistances of both heat exchangers decreases. Particularly, for thermoelectric generators, a decrease by 10 % in both thermal resistances leads to an average increase in the electric power generated by around 8 %.

The optimization of finned dissipators used in thermoelectric refrigerators allows the reduction of their thermal resistances, which in turn increases the COP of these

modules makes the fan rotate and, therefore, provides forced convection over the dissipator, which improves the heat transfer efficiency and decreases the thermal resistance between

0 50 100 150 200 250

.

Fig. 13. Thermal resistances between heat source and ambient versus heat flux generated.

Thermoelectric technology has evolved significantly in the last decade, fundamentally due to the improvement of thermoelectric materials, which boosted the commercialization of novel applications in the civil market. However, efficiencies of thermoelectric devices that provide heating, cooling and generation of electric power are still low. In this sense, the scientific community considers essential the optimization of heat exchangers that must be

This chapter has shown the major influence of the heat exchangers on the efficiency of thermoelectric devices, and indicates that this efficiency rises as the thermal resistances of both heat exchangers decreases. Particularly, for thermoelectric generators, a decrease by 10 % in both thermal resistances leads to an average increase in the electric power generated by

The optimization of finned dissipators used in thermoelectric refrigerators allows the reduction of their thermal resistances, which in turn increases the COP of these

Device alone

Device with dissipator

**Q (W)**

the heat source and the ambient by 30 % without electricity consumption.

Device with TSC system

0,4

**5. Conclusions** 

around 8 %.

mounted at either end of the Peltier modules.

0,6

0,8

1,0

1,2

1,4

1,6

1,8

**R (ºC/W)**

thermoelectric devices. However, finned dissipators do not represent the most efficient heat exchangers, since constriction thermal resistances restrict, to a great extent, the global thermal resistance of the dissipator.

Two different heat exchangers are presented, one for the hot side and the other for the cold side of the Peltier modules. On one hand, the TSF (phase-change thermosyphon) reduces the thermal resistance between the hot side of the module and the ambient by 51 %, which means an increase in the COP of thermoelectric refrigerators by 36.5 %. Subsequently, this TSF was improved and a thermosyphon with natural convection (TSV) came out, thus eliminating all moving parts. On the other hand, for the cold side of the Peltier modules, the described TMP joins thermosyphon and capillarity lift technologies and improves by 37 % the thermal resistance of a similar-in-size finned dissipator. Finally, a prototype that included the developed thermosyphons TSV and TMP showed an improvement on the COP by 66 % with respect to that attained with a similar prototype but including finned dissipators.

In the last part of the chapter, the novel concept of thermoelectric self cooling has been introduced, which can be applied to any device that generates a certain amount of heat, such as electrical power converters, transformers and control systems. When the thermoelectric self cooling system is installed, the thermal resistance between the heat source and the environment decreases by up to 30 % without electricity consumption.
