Evaluation of the Performance of Alkali Metal Thermoelectric Converter with Potassium β”-Alumina solid Electrolyte

The replacement of working fluid of the alkali metal themoelectric converter (AMTEC) is eminently suitable for achieving higher performance under lower operating temperatures. Potassium is a reasonable condidate because it has lower latent heat of vaporization and higher vapor pressure than sodium over the AMTEC operating conditions. The performance of the AMTEC cycle with potassium as the working fluid has been evaluated and discussed based on the recently reported ionic conductivity data of potassium-β”-alumina solid electrolyte. The calculated results show that the replacement of working fluid increases the peak efficiency from 28% to 31% at 1100 K with 1 mm thick β”-alumina solid electrolyte. If the thinner solid electrolyte is practically developed, the improvement of the performance can obviously be recognized because of the decrease of ionic conductivity.