Design and optimization of three segmented thermoelectric generator for nuclear reactor application

Abstract

With the scientific exploration in deep space and deep sea, traditional fossil energy and solar energy cannot supply energy for deep space aircrafts and deep sea vehicles continuously, new energy power systems with the features of long endurance, high reliability and high energy density are imperative. Small nuclear reactor has become one of the best solutions for deep space energy demand in the future due to its strong environmental adaptability and long-life time. To improve the reliability of the static heat pipe reactor, the thermoelectric generators (TEGs) are utilized to convert fission heat into electrical energy. Focusing on the demands of improving the conversion efficiency, a new three segmented TEG is proposed based on the Bi2Te3, CoSb3 and Half-Heusler thermoelectric materials in this paper. Combined with the application requirements of heat pipe reactor, the geometric configuration such as different heights and the cross-sectional area of the three different materials in the PN legs is designed and optimized under different heat flux boundary conditions. The influences of contact electrical resistance and contact thermal resistance on the conversion efficiency have been investigated. When the contact electrical resistivity increases from 0.01 μΩ cm2 to 1000 μΩ cm2, the conversion efficiency loss increases from 2.6% to 80.1%. As the surface roughness rises from 0.1 μm to 100 μm, the conversion efficiency loss increases from 0.9% to 42.7%. Based on the heat flux boundary conditions provided by the heat pipes, the thermoelectric conversion performances of three segmented TEG under different external loads are investigated. Through the geometric optimization of the three segmented TEG with total height 20 mm, the thermoelectric conversion efficiency improves from 6.9% to 15.34%. For the simulation heat flux density conditions of 70 kW m−2, 75 kW m−2, 80 kW m−2, 85 kW m−2 and 90 kW m−2, the maximum output power of a thermoelectric generator can reach 8.56W, 9.71W, 10.85W, 12.00W, and 13.11W, respectively. The output characteristics of the three segmented TEGs meet the design demands of the static conversion system.