Performance enhancement of a thermoelectric harvester with a PCM/Metal foam composite

Abstract

The present numerical investigation examines the performance improvement of thermoelectric generators (TEGs) by using phase change materials (PCM) and porous medium. Due to the high latent heat of PCMs, both sides of the TEG were filled with paraffin RT35 (on the cold-side) and paraffin RT69 (on the hot-side). The PCM in the cold-side of the TEG was used as a heat-sink whereas the PCM in hot-side of the TEG was used to reduce the output voltage fluctuations. Since the system was periodically subjected to heat flux from an external heat source, the paraffin in the hot-side of the TEG was also used to generate a continuous thermal heat when the heat source was cut-off. To increase the thermal conductivity of the phase change material, this investigation studied the effect of using the copper porous medium with different porosities (0.80, 0.90, and 0.95) and three different pores per inches (PPI) as 10, 20, and 40. The results show that the use of porous on the cold-side of the TEG produces more electrical energy and output voltage compared to (i) having porous medium on the hot-side and (ii) using PCM without porous medium on both sides of the thermoelectric generator. Furthermore, the results indicated that the TEG performance enhanced by increasing PPI and reducing porosity. As a result, by increasing the PPI from 10 to 40 (at 0.80 porosity) and by reducing porosity from 0.95 to 0.80 (at PPI 20), the electricity generated increases by 13.57 and 5.36%, respectively.