Computationally Modelling the Use of Nanotechnology to Enhance the Performance of Thermoelectric Materials

Abstract

The increased focus on global climate change has meant that the thermoelectric market has received considerably more attention. There are many processes producing large amounts of waste heat that can be utilised to generate electrical energy. Thermoelectric devices have long suffered with low efficiencies, but this can be addressed in principle by improving the performance of the thermoelectric materials these devices are manufactured with. This paper investigates the thermoelectric performance of market standard thermoelectric materials before analysing how this performance can be improved through the adoption of various nanotechnology techniques. This analysis is carried out through the computational simulation of the materials over low-, mid- and high-temperature ranges. In the low-temperature range, through the use of nanopores and full frequency phonon scattering, Mg0.97Zn0.03Ag0.9Sb0.95 performed best with a ZT value of 1.45 at 433 K. Across the mid-temperature range a potentially industry leading ZT value of 2.08 was reached by AgSbTe1.85Se0.15. This was carried out by simulating the effect of band engineering and the introduction of dense stacking faults due to the addition of Se into AgSbTe2. AgSbTe1.85Se0.15 cannot be implemented in devices operating above 673 K because it degrades too quickly. Therefore, for the top 200 K of the mid-temperature range a PbBi0.002Te–15% Ag2Te nanocomposite performed best with a maximum ZT of 2.04 at 753 K and maximum efficiency of 23.27 at 813 K. In the high-temperature range, through the doping of hafnium (Hf) the nanostructured FeNb0.88Hf0.12Sb recorded the highest ZT value of 1.49 at 1273 K. This was closely followed by Fe1.05Nb0.75Ti0.25Sb, which recorded a ZT value of 1.31 at 1133 K. This makes Fe1.05Nb0.75Ti0.25Sb an attractive substitute for FeNb0.88Hf0.12Sb due to the much lower cost and far greater abundance of titanium (Ti) compared with hafnium.

Effect of Thermoelectric Legs on Electrical Performance of Single Leg Teg using Multiphyiscs Simulation

“…It is a solid-state device and it is made up of semiconductors placed between two ceramic surfaces and connected by metal parts which can be seen in Prasad and Thiagarajan [6], Doraghi et al, [7], Jaegle [8] and Tulaev [9]. To create thermoelectric, n-type and p-type semiconductors are thermally coupled in parallel and electrically in series was mentioned by Anitha et al, [10], Asenath-Smith et al, [11] and Spriggs and Wang [12]. Samsudin et al, [13] said that Malaysia is exploring for alternative fuels to produce energy in order to overcome the difficulties and create a sector for sustainable power generation.…”

“…The best material for thermoelectric applications at low to medium temperatures, according to Spriggs and Wang [12] evaluation of the thermoelectric performance of commercially available thermoelectric materials, is bismuth. The efficiency of the Bi2Te3 thermoelectric material is 2.57% and 3.75% on the hot side temperature for 100°C and 150°C, respectively, according to Hu et al, [20] whom investigated into the electrical and thermal contact of the material between TEG legs.…”