Thermoelectric Conversion of Waste Heat into Small Power

ABSTRACT

Thermoelectric generators can function as reliable, low maintenance sources of small DC power. They are best suited for applications where an abundant source of heat is already available such as waste heat from power plants and gas pipelines. They can serve as independent sources of power for sensors and communication devices. The objective of this research was to design and fabricate a working prototype of a thermoelectric generator to produce small power for sensors, using waste process heat available at around 120-200°C. The aim was to generate small power of about 5 W. To simulate the heat source, rheostat controlled heating elements inserted in an aluminium block were used. Thermoelectric modules were mounted on the heat source, so that they were thermally parallel, and were connected in series, electrically. Two heat sinks were designed and fabricated and were mounted on the cold side of the modules. The generator was able to produce a net output power of 5.2 W at 12.2 V for a source temperature of 177 degree Celsius and an ambient temperature of ~17 degree Celsius when the fans were powered by the generator itself. The power and voltage generated was studied for different source temperatures (in the range 120 - 200 degree Celsius) and load resistances. These measurements were obtained for two cases. In one case the cooling fans were powered by an external source and in the other, by the generator itself. The effect of varying the fan air flow rate on the system performance was also studied.

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