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Feasibility Study and Conceptual Design of A Radioisotope Thermoelectric Generator

Amirnasab, Mohammad | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46314 (46)
  4. University: Sharif University of Technology
  5. Department: Energy Engineering
  6. Advisor(s): Vosoughi, Naser; Feghhi, Amir Hosain
  7. Abstract:
  8. Radioisotope thermoelectric generator (RTG) is a kind of nuclear batteries, in which thermal energy resulting from the discharge of charged particles decayed of radioisotope, using thermoelectric arrays, can be converted to electrical energy. In this study, the different kinds of RTGs introduced and applications of them have been expressed. All types of radioisotopes used in RTGs have been reviewed and the most suitable of them in terms of maximum thermal power density and minimum dose rate have been selected. All types of thermoelectrics used in RTGs have been reviewed and the most suitable of them in terms of the range of temperature and maximum efficiency have been selected.
    In this study At first, in order to validate the results, thermal and electrical analysis for SKTA-RTG has been performed, and more, this analysis for MMRTG (which dimensions of some of its components must be determined) has been done. Also the feasibility study of SKTA-RTG has been investigated. Simulations of the RTG are includes nuclear computations for heat source in order to determine dose rate around the heat source, using the Monte Carlo N-Particle transport code MCNPX, and thermal analysis for the entire RTG to determine the temperature calibration point of the heat source, and the hot and cold junction temperature of thermoelectrics, and electrothermal analysis for thermoelectrics to determine thermoelectric voltage generated across a junction of thermoelectric materials p and n subjected to a junction temperature difference (TH-TC). Thermal and electrothermal analysis have been performed using ANSYS software.
    The results of the simulations indicate that radioisotopes that are most suitable for use in RTG are 238Pu and 241Am. Also the most appropriate thermoelectric, when every legs of unicouple includes one thermoelectric material, are crystals of Skutterudite p-legs of CeFe3.5Co0.5Sb12 and n-legs of CoSb3. This crystals are about 10% conversion efficiency. This crystals are used in SKTA-RTG. Thermal and electrical analysis for MMRTG indicate that the appropriate length for unicouples is 20 mm and the internal diameter and thickness of graphite sleeve around heat sources are 156.08 mm and 2 mm respectively. Also the appropriate thickness for aluminum housing is 4 mm and width of fin is 203 mm. In the optimal working point of MMRTG, load resistance equal to 7.8 Ω and Total circuit current is 3.93 A and load voltage and electrical power is 30.68 V and 114.62 W respectively. The results that obtained from the simulations, have good correspondence with the experiment result
  9. Keywords:
  10. Thermoelectric ; Thermal Analysis ; Efficiency ; Rodioisotop Thermoelectric Generator (RTG) ; General Purpose Heat Source (GPHS) ; Equivalent Dose Rate

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