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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Non-Equilibrium Electron Gas Thermodynamic Cycle with Nano Features

Get access (open in a dialog) DOI: 10.1615/IHTC15.tdy.009243
pages 7915-7927

Abstract

We discuss a non-equilibrium electronic heat engine that generates electrical power from a radiative heat source such as the sun. Electrons in a solid, occupy energy levels based on the Fermi-Dirac distribution following the Pauli Exclusion Principle. 'Hot electrons' are those that occupy higher energy states and have an effective temperature higher than other electrons and the lattice, where the behavior of free electrons in a solid is commonly accepted as a Fermi . The non-equilibrium state considers a very short time interval, <10−12 seconds, after the heat energy is absorbed before electron-phonon interactions begin to dominate the energy transport. The proposed device uses geometrical concentration of electron under an electric field which increases the pressure of the electron . Nano-scale feature sizes enable hot electrons to arrive at contacts quickly before thermalization with the lattice takes effect. For quantitative analysis, we assume an electron temperature of about 3000 K which corresponds to ∼7000x the solar concentration. The lattice temperature stays near room temperature. The process is similar to a thermodynamic Otto cycle for an internal combustion heat engine. The ideal performance is calculated based on the Fermi gas theory using this analogy. We compare the upper limit efficiencies of the non-equilibrium electron gas thermodynamic cycle with other approaches, such as hot carrier solar cells and thermophotovolatic devices.