A recirculating thermoelectric generator based on sodium β″ alumina

Abstract

A convectively cooled, recirculating thermoelectric generator based on β″ alumina has been designed and operated over the temperature range of 400–600 °C. The design employs a stainless-steel wick and flame sprayed molybdenum electrodes and the unit can be assembled and operated with ease. A full treatment of all thermal and electrical flows is given and theoretical efficiencies of 10%–15% are predicted. Critical parameters are the internal resistance and radiation coefficients for thermal losses, while it is also shown that the flow of sodium within the electrode and the geometry of the evaporating and condensing surfaces is of importance in limiting the measured efficiency to 1%–3%. Units have been operated for up to 3000 h.