Thermal Designing of an Inner Cathode Type Alkali Metal Thermal to Electric Conversion (AMTEC) Cell

Abstract

Thermal designing of an inner electrode type alkali metal thermal to electric conversion (AMTEC) cell is discussed. The inner electrode type is a method of depositing cathodes inside beta”-alumina solid electrolyte (BASE) tubes. The proposed inner electrode type cell is characterized by its enhanced heat exchange characteristics and its simple structure without bonding of solid electrolyte ceramic and metal parts. A method of using non sintered graphite powder as a wick has been proposed. The maximum capillary force and flow resistance were measured, and using the obtained data, the inner electrode type cell was designed. A cell efficiency of 19％ at a temperature condition of 950 K - 500 K was calculated. Compared to the outer electrode type, the output power is increased by 2 times and the efficiency is improved by 25%. The examined result of thermal designing showed that the wick performance and the distance between the high and low temperature sides greatly affect the conversion efficiency. The calculated efficiency of the cell with a distance of 100 mm is η= 19％, and with 200 mm it is η = 24％.