6. Conclusions

In this chapter, Thomson effect and leg geometry parameters on performance in a hybrid twostage TEC were evaluated. For this purpose, the basics of two-stage thermoelectric cooler devices are analysed according to one dimension out-of-equilibrium thermodynamics using TDPM model. Two different semiconductor materials were used in all calculations. Results show, Thomson effect leads to a slight improvement on the performance and when the ratio of Thomson coefficients between both stages, τ<sup>r</sup> ¼ τ1=τ2, increases, more cooling power can be achieved. We show that it is convenient to analyse optimal configuration of materials that must be used in each stage, showing that the material with a higher value of Seebeck coefficient must be place in the first stage. The main interest is to improve cooling power, thereby, a new procedure based on optimum leg geometric parameters of the semiconductor elements, is presented. Our analysis shows that, hybrid system reaches maximum cooling power, 15.9% greater than the one-stage system, for the case when the geometric parameter is ω<sup>1</sup> 6¼ ω2. An important advantage of this work is that result can be confirmed in laboratories, as prototypes are made by mainly using bismuth telluride, which is the basis of the materials we use in all calculations.
