A review on methods and materials for optimizing thermionic regeneration system

Abstract

The direct conversion of heat to electricity is a prominent way of energy generation. This could be achieved by direct energy converters such as thermoelectric and thermionic converters. It is evident from the study that the thermionic energy conversion has higher conversion efficiency as compared with other direct conversion methods. Thermionic energy converter with low work function materials is an emerging field of research. The methods for optimization of Thermionic energy converter are focusing towards space charge limitation and electron acceleration. Magnetic/electric field, electron beaming shows best results in improvement of conversion efficiency. Nanostructure materials can exhibit lower work function for better performance. Graphene is recently being studied for obtaining lower work functions for emitter and collectors. Recent advancements in the space charge mitigation and collector and emitter materials are discussed in the paper. This paper provides the assessment of advancement in materials and methods for thermionic energy generation.