Development of low grade waste heat ther

This research aimed to develop a 50 watt thermoelectric power generator using low grade waste heat as a heat source, in order to recover and utilize the excess heat in cooling systems of industrial processes and high activity radioisotope sources. Electricity generation was based on the reverse operation of a thermoelectric cooling (TEC) device. The TEC devices were modified and assembled into a set of thermal cell modules operating at a temperature less than 100°C. The developed power generator consisted of 4 modules, each generating 15 watts. Two cascade modules were connected in parallel. Each module comprised of 96 TEC devices, which were connected in series. The hot side of each module was mounted on an aluminum heat transfer pipe with dimensions 12.2×12.2×50 cm. Heat sinks were installed on the cold side with cooling fans to provide forced air cooling. To test electricity generation in the experiment, water steam was used as a heat source instead of low grade waste heat. The open-circuit direct current (DC) of 250 V and the short-circuit current of 1.2 A was achieved with the following operating conditions: a hot side temperature of 96°C and a temperature difference between the hot and cold sides of 25°C. The DC power output was inverted to an AC power source of 220 V with 50 Hz frequency, which can continuously supply more than 50 watts of power to a resistive load as long as the heat source was applied to the system. The system achieved an electrical conversion efficiency of about 0.47 percent with the capital cost of 70 US$/W.