An Energy Harvesting Perspective of a Perovskite Based Thermoelectric Module: Fabrication and Evaluation
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https://doi.org/10.1007/s11664-020-08516-w Ó 2020 The Minerals, Metals & Materials Society
PROGRESS AND CHALLENGES WITH PEROVSKITE MATERIALS AND DEVICES
An Energy Harvesting Perspective of a Perovskite Based Thermoelectric Module: Fabrication and Evaluation ABANTI NAG
1,3
and K. SATHIYAMOORTHY2
1.—Materials Science Division, CSIR-National Aerospace Laboratories, Bangalore 560017, India. 2.—Propulsion Division, CSIR-National Aerospace Laboratories, Bangalore 560017, India. 3.—e-mail: [email protected]
Oxide thermoelectric materials based on n-type perovskite Ca0.99Dy0.005Lu0.005MnO3 and p-type layered Ca3Co4O9 were developed and their application towards energy harvesting from waste heat was demonstrated. The nand p-type oxides were synthesized by a sol–gel route followed by hot-press sintering to achieve densities that were 95–98% of the theoretical values. The doping concentrations in the thermoelectric materials were optimized to achieve lower electrical resistivity with moderate Seebeck coefficients that yielded power factors close to 550 lW m1 K2 at 950 K. A 14-element thermoelectric (TE) module was fabricated by connecting the developed n- and ptype oxide materials electrically in series and thermally in parallel. The electrical connectivity was achieved using Ag conductive paste followed by sandwiching the n and p-type materials between two insulating alumina plates. The module was tested in a simulated environment of hot gas flow with hot-side temperatures up to 623 K. The module generated an output voltage of 0.34 V with a power density of 0.9 mW cm2 at 623 K. Key words: Thermoelectric module, energy harvesting, n and p-type materials, waste heat recovery
Z S q j TH TC DT W d h m N h kB J S
List of Symbols Figure-of-merit Seebeck coefficient Resistivity Thermal conductivity Hot-side temperature Cold-side temperature Temperature gradient Effective eg band width Bond length Bond angle Effective mass of carriers Free carrier concentration Plank constant Boltzmann constant Electrical current density Thompson coefficient
(Received May 8, 2020; accepted September 23, 2020)
QH QC K R I V P
Heat flow at hot junction Heat flow at cold junction Thermal conductance Electrical resistance Current flow Output voltage Output power
INTRODUCTION Perovskite oxides are mostly based on 3d transition metals and present a wide variety of physical properties, such as colossal magnetoresistance and multiferroicity, that are of great importance in microelectronics and telecommunication. In the field of thermoelectric energy conversion, perovskite oxides play a major role as they are non-toxic,
Nag and Sathiyamoorthy
chemically and thermally stable at high temperatures, and eco-friendly; most importantly, these materials are synthesized from abundant elements and are also cost-effective.1–4 Thermoelectric energy-harvesting devices fabricated using all-oxide materials have the added advantage of device durability in open atmosphere and operational flexibility at high temperatures.5–8 The physics of thermoelectricity
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