Optimization and Analysis of an Output Performance Calculation Model for a Cesium Thermionic Energy Converter

We propose a modified Kuznetsov model to calculate the output performance of a cesium thermionic energy converter (TEC). Based on this model, it can be found that the power density and conversion efficiency increase continuously as the emitter temperature increases. Reducing the work function of the emitter can significantly increase the power density, whereas the conversion efficiency with the change of the work function shows a parabolic trend with a downward-facing opening. The power density of the TEC has an approximate step function relation with the collector temperature, which should be selected at the inflection point of the function curve during device design. Considering the effects of electrode spacing and cesium vapor pressure, the product of the two influencing factors should be kept at approximately 74 Pa mm to reduce the barrier level of the electrode gap. Through further structural optimization design, the conversion efficiency of the TEC could be improved at a 1600 K emitter temperature.