Thermoelectric materials and device: recover waste-heat from heat exchanger of power plant

Abstract

Electricity generation is always the most energy wasting industry in the world, almost half of the energy supply is lost to the surrounding due to condensation and the thermodynamic processes. The project is to design a module consist of thermoelectric generators to recover the waste heat into electricity in the heat exchanger (condenser) of the power plant. Commercially available thermoelectric generators, Bi2Te3, are used, the cost of TEG is under control in a reasonable range. The thermoelectric generators will generate electricity with a temperature difference on the junctions of it. The module works when the steam turbine is generating electricity. Experiments have to be taken to test whether the idea of the TE module works. The actual module cannot be made because of the limiting instrument. Instead, a aluminum box with drilled holes was constructed to simulate the actual situation. With fresh water circulates around among the aluminum box, the setup acts as a simulator of the heat exchanger. The paste thermoelectric generators together with the aluminum base act as the TE module. The heat plate acts as the hot steam side, and the circulating water acts as cold side filled with water. Releasing latent heat of vaporization in the heat exchanger (condenser), the hot steam which is about 60℃ passing out from the turbines passes through the heat exchanger and the latent heat is being absorbed by the circulating water with ambient temperature 25℃. A stable 35℃ or above temperature difference exists on the water pipe of the heat exchanger. The TE module can be applied on the place with such temperature difference. Performance of the simulator including the internal resistance, power output, conductivity and Seebeck coefficient are recorded. The improvements in efficiency, installation, thermal conductivity and possible problems in real situation have been discussed. Also, for the large scale application of the TE module, the overall generated electricity is estimated as a reference.