High efficiency segmented thermoelectric unicouples

Abstract

Highly efficient, segmented thermoelectric unicouple incorporating advanced thermoelectric materials with superior thermoelectric figures of merit are currently being developed at the Jet Propulsion Laboratory (JPL). These segmented unicouples incorporate a combination of state-of-the-art thermoelectric materials based on Bi2Te3 and novel p-type Zn4Sb3, p-type CeFe4Sb12-based alloys and n-type CoSb3-based alloys developed at JPL. They can be integrated into thermoelectric power generation modules which could be used for a variety of applications making use of waste heat recovery and also potentially in Radioisotope Power Systems (RPSs) that are needed for several NASA missions planned over the next few years. These missions call for electrical power requirements ranging from 20 to 200 watts and 6 to 15 years mission duration. The resulting RPSs would not only have a high specific power (∼8 We/kg) that is about twice that of the state-of-the-art Radioisotope Thermoelectric Generators (RTGs), but also a higher overall efficiency (>14%), halving the 238 PuO2 needed for a given electric power requirement. These advanced RPSs would couple the novel, segmented thermoelectric unicouples (STUs) to one or several standard General Purpose Heat Source (GPHS) modules (or bricks), depending on the electric power requirements. The advanced STUs would operate at a hot side temperature of about 1000 K, alleviating some of the concerns associated with the high temperature operation of current GPHS-RTGs (∼1300 K), and at a cold side temperature of ∼400 K. The latest developments in the fabrication and testing of the advanced segmented thermoelectric unicouples are presented and discussed.