Optimization of a thermoelectric system for power generation

Nowadays the utilization of renewable energy sources is very important to support the traditional ones, and besides in order to achieve the objectives fixed by the Kyoto Protocol. In this context also well known technologies related to the electric energy production, formerly not suitable - due to the technological level of the components or due to the high costs linked to the system efficiency -, may found a suitable collocation. Among these technologies, the thermoelectric effect may be very advantageous in some particular applications of small power. A power generation system utilizing this technology was studied by the Authors. This system utilizes the thermal difference between a lower temperature sink, e.g. a water reservoir, and a higher temperature source, such as reject heat or solar energy captured by an extended surface. The system is basically constituted by two heat exchangers and by a hydraulic circuit with a circulating pump. The thermal source can be, for example, solar radiation or waste heat resulting from some industrial processes. The thermal generator is here given by some thermocouples placed on the internal surface of an heat exchanger, located inside the water body and filled up with the hot water coming from the energy source. In this paper, the physical mechanisms and the energy balances governing the system are described in order of evaluating its optimal design. Fixed the characteristics of heat source, the system is optimized with the aim to have the highest energetic efficiency.