The heat pipe and thermosyphon are passive heat transfer devices with phase change, which can be applied for thermal management of thermoelectric cooling, such as the TEC hot side. The heat pipes basically consist of a metal tube sealed with capillary structure internally that is embedded with a working fluid. This capillary structure can be made of screen meshes, grooves, or sintered media. The thermosyphon is a heat pipe assisted by gravity, because it has no capillary structure. Then, in this chapter, manufacturing of low cost and easy-to-manufacture heat pipes and thermosyphon is described in detail, and an experimental evaluation of their thermal performance is accomplished. The considered devices were a rod, a thermosyphon, a mesh heat pipe, a grooved heat pipe, and a sintered heat pipe. According to the behavior of the global thermal resistance and the effective thermal conductivity, the passive devices operated satisfactorily with the exception of the rod and the thermosyphon in the horizontal position. The heat pipes were the best among the tested devices and the best position was vertical.
Part of the book: Bringing Thermoelectricity into Reality
In this chapter, experimental analysis of the direct conversion of thermal energy into electric energy was carried out, in order to encourage the conscious use of energy and to reduce waste. The conversion of thermal energy into electrical energy occurs in a thermoelectric generator through the Seebeck effect. This effect is associated with the appearance of an electric potential difference between two different materials, placed in contact at different temperatures. This relation between temperature and electrical properties of the material is known as thermoelectricity. This experimental study has as objective the obtaining of operating characteristic curves of the thermoelectric generator TEG1-12611-6.0, for different temperature gradients and under constant pressure between the heater plate and the heat sink. Resistors were used to heat the thermoelectric generator, which simulates the residual heat, and insulation material to minimize the dissipation of heat to the environment. For cooling, a heat exchanger was used in order to maximize the temperature difference between the sides of the thermoelectric generator. In this way, it was possible to perform an experimental analysis of the obtained electric power for different temperature ranges between the faces of the generator and, with this, verify the applicability in real systems.
Part of the book: Advanced Thermoelectric Materials for Energy Harvesting Applications