A numerical study on the design trade-offs of a thin-film thermoelectric generator for large-area applications

Abstract

Thin-film thermoelectric generators with a novel folding scheme are proposed for large-area, low energydensity applications. Both the electrical current and heat transfer are in the plane of the thermoelectric thinfilm, yet the heat transfer is across the plane of the modulesimilar to conventional bulk thermoelectric modules. With such designs, the heat leakage through the module itself can be minimized and the available temperature gradient maximized. Different from the previously reported corrugated thermoelectric generators, the proposed folding scheme enables high packing densities without compromising the thermal contact area to the heat source and sink. The significance of various thermal transport, or leakage, mechanisms in relation to power production is demonstrated for different packing densities and thicknesses of the module under heat sink-limited conditions. It is shown that the power factor is more important than ZT for predicting the power output of such thin-film devices. As very thin thermoelectric films are employed with modest temperature gradients, high aspect-ratio elements are needed to meet theusually ignoredrequirements of practical applications for the current. With the design trade-offs considered, the proposed devices may enable the exploitation of thermoelectric energy harvesting in newlarge-areaapplications at reasonable cost. KEYWORDS: thermoelectric generator; large-area TEG; thin-film, in-plane heat transfer; FEM simulations; computational TEG design © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This is a post-peer-review, pre-copyedit version of an article published in Renewable Energy. The final authenticated version is available online at: https://doi.

Large-area implementation and critical evaluation of the material and fabrication aspects of a thin-film thermoelectric generator based on aluminum-doped zinc oxide

“…In principle, it should be possible to increase the folding density without increasing significantly the heat leakage through the module, as shown in Ref. [14], implying that the power output can be still increased above the solid black line of Fig. 5, if high-performance thermoelectric materials are available.…”

“…1b and Refs. [14,15]). The performance of the TEG module was characterized with a setup consisting of a temperature controlled heat plate under the TEG and ice on the top to cool the upper surface.…”

“…The preliminary experimental results of the folded TEG have also been reported in the context of performing as a power source for a window-integrated wireless sensor node with the TEGs measured in planar [15] and single module formats [16]. The principle of the TEG concept [14] and schematics of the folded TEGs before and after folding, as well as a picture of a fabricated TEG module of eleven TEG elements are shown in Fig. 1.…”

Mathematical model and optimization of a thin-film thermoelectric generator

“…However, the fabrication of suspended interconnects may not always be possible and so an insulating/supporting material of silicon dioxide is used in between the thermoelements. The design is similar to the design proposed in [31], which investigated a design using longer thermoelements but still having multiple rows of these longer elements; their investigation focused on fabrication by folding the substrate. The investigation here is not limited to any particular fabrication method as long as the parameters investigated are able to be tuned to the optimum values.…”

A Thin-Film Thermoelectric Generator for Large-Area Applications

“…However, the most abundant thermal gradients are small and do not allow the inclusion of efficient heatsinks, which makes the conventional TEGs unsuitable for such low-energy-density applications. A new thin-film TEG design applicable for large-area, heatsink-limited applications has previously been proposed and the performance analyzed computationally [1,2]. With such designs, the heat leakage through the module itself can be minimized and the available temperature gradient maximized.…”