Development of High Efficiency Segmented Thermoelectric Couples

Abstract

= maximum couple thermal-to-electric conversion efficiency GPHS-RTG = General Purpose Heat Source Radioisotope Thermoelectric Generator MMRTG = Multi-mission Radioisotope Thermoelectric Generator RTG = radioisotope thermoelectric generator T H = hot junction temperature T C = cold junction temperature T avg = average couple temperature Z = thermoelectric figure of merit

Concentrating solar thermoelectric generators with a peak efficiency of 7.4%

“…26,27 Significant progress has been made on improving and developing new thermoelectric materials in recent years, however actual device demonstrations have been scarce and are mostly motivated by waste heat recovery applications. [28][29][30][31][32][33][34] The auxiliary efficiency in Eq. (1) accounts for possible system parasitic losses such as electricity consumption for pumping and cooling.…”

“…Thermoelectric materials typically perform best in a relatively narrow temperature range. 11,27,31,33,39 Modeling has shown that higher performance can be achieved by segmenting thermoelectric legs with different materials permitting large operating temperature differences. 11,39 For example, by using a low-temperature material such as bismuth telluride operating up to ~250 °C and a high-temperature material such as skutterudite operating above ~250 °C, a CSTEG can theoretically achieve an efficiency of over 10%.…”

“…31,33 Additionally, there are several avenues to further improve the STEG performance: (1) increasing optical solar concentration which increases both abs and teg, (2) reducing the infrared emittance of the solar absorber, (3) improving thermoelectric materials, and (4) However, operating a STEG with such a large operating temperature difference requires TEGs with thermoelectric materials that can operate efficiently at temperatures up to 1000 °C. Recent progress made in high-temperature thermoelectric materials and device demonstrations raises hope of achieving predicted efficiencies.…”

“…Recent progress made in high-temperature thermoelectric materials and device demonstrations raises hope of achieving predicted efficiencies. 19,31,33 One of the main advantages of CSP is dispatchability by using inexpensive thermal storage. Solar CSTEG can also be coupled to a STEG with a blackbody solar absorber (solar absorptance and IR emittance of 1) and thermoelectric material with effective ZT of 1, 1.5 and 2. thermal storage system, although the device and system configurations would need to be redesigned.…”

Solid-Liquid Interdiffusion (SLID) Bonding of p-Type Skutterudite Thermoelectric Material Using Al-Ni Interlayers

“…The conventional thermoelectric device manufacturing comprises of labour-intensive methodology including soldering, brazing and adhesive bonding [4] which are limited by the thermal stability (as the braze melting temperature is normally its re-melting temperature) and the extensive growth of reaction layers at the thermoelectric–interconnect interfaces, causing mechanical or electrical deterioration of the entire assembly. In the conventional skutterudite devices, metal interconnects are joined to the metallized semiconductor elements to provide permanent interconnection either by the mechanical (i.e., using compression springs [5]) or chemical (i.e., solid-state diffusion bonding [6,7] or brazing [8]) methods of joining. Designing a suitable metallization and bonding technique for the skutterudite family of compounds is particularly difficult with the complex reactivity of their individual components, since antimony (Sb) can react with most of the transition metals to form brittle antimonide intermetallic compounds (IMCs).…”