https://doi.org/10.1140/epjs/s11734-023-00789-6
Regular Article
Enhancement of thermoelectric energy harvesting of thermal fluctuations with thermocapillary flows in phase-change materials embedded in metallic foams
Department of Applied Mathematics to the Aerospace Engineering, School of Aerospace Engineering, Universidad Politécnica de Madrid (UPM), Plaza Cardenal Cisneros 3, 28040, Madrid, Spain
Received:
4
July
2022
Accepted:
30
January
2023
Published online:
15
February
2023
We present a complete model of a thermoelectric micro-energy harvester to transform ambient thermal fluctuations into electricity that couples a thermoelectric generator (TEG) to a heat storage unit (HSU) filled by a phase-change material embedded in a metallic foam subjected to convective flows due to the Marangoni effect. Convective heat transfer at the HSU is simulated with the Darcy–Brinkman–Forchheimer bulk equations, a shear stress boundary depending on the porosity, and the phase change with the enthalpy-porosity method. The porous matrix weakens the Marangoni effect by decreasing the surface shear stress while increasing the effective thermal conductivity. Introducing the metallic foam multiplies the efficiency in the transformation between thermal spatial gradients and electric energy with respect to only Marangoni driving. For a heat storage unit of 8 cm 
1 cm, Darcy number Da 
coupled to a TEG with Seebeck coefficient 0.027, we find that the harvested energy multiplies with respect to a base PCM driving by Marangoni: 3.2 times (23.6 J) for porosity 
, 3.9 times (28.4 J) for 
, 4.3 times (31 J) for 
. Decreasing the permeability augments the resistance to the convective flows and slightly reduces the electric energy generated.
© The Author(s) 2023
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
