Speaker
Description
Electricity may be generated in a highly efficient manner from heat of various sources by means of thermionic energy converters (TICs). However, the potential of this energy conversion technology is always hindered by the space charge effect, which drastically reduces the electron transport within this converter. To overcome this challenge, external fields like electric and magnetic fields are incorporated to mitigate the effect of space charge in TICs. In this paper, an irreversible thermionic energy converter model utilizing these external fields, namely the thermal electronic converter (TEC), is proposed. The model of the TEC consisting of an accelerating gate, an emitter, and a collector is proposed, in which the various heat losses including the far- and near-field thermal radiation are taken into account. A formula for the overall efficiency of the system is analytically derived. For given values of the ratio of the front surface area of the absorber to that of the emitter and the vacuum gap between the emitter and the collector, the operating temperatures of the emitter and collector are determined by solving the energy balance equations. The maximum efficiency of the TEC is calculated for given values of the work functions of the emitter and collector materials, and some key parameters such as the net current density of the TEC, operating temperatures of the emitter and collector, vacuum gap between the emitter and the collector, and area ratio of the absorber to the emitter are optimally determined. Furthermore, the effects of the work functions on the performance of the TEC are discussed, and several parametric selection criteria are obtained. This study provides a comprehensive parametric design and performance evaluation of the TEC, offering insights into optimizing its efficiency for practical applications.
Keywords
Alternative Energy Conversion, Thermionic energy conversion, Clean Energy Generation, Direct energy conversion, Space charge suppression
