In a thermionic device, electrons evaporate from a hot cathode into a vacuum and are collected by a cooler anode, generating current. Defect engineering of photocatalysts for solar energy. Solar energy conversion with photonenhanced thermionic. Some 225 faculty and staff at stanford are engaged in energy related research. Consequently, thermionic systems with high powertoweight ratios are possible. Thermionic and photoexcited electron emission for energy. Thermionic emission is a wellknown quantum phenomenon which describes electron evaporation from the surface of materials, based on changing the energy distribution of electrons by elevating temperature. Diamond based isothermal photonenhanced thermionic solar. City, vietnam ffaculty of electrical and electronics engineering, ton duc. Solidstate and vacuum thermionic energy conversion 5a. We are exploring innovative methods of optimizing thermionic energy converters including integration of advanced materials and use of standard semiconductor processing, as well as looking into novel conversion concepts like photonenhanced thermionic emission. Despite having a huge potential as an efficient direct energy conversion device, the progress in vacuumbased thermionic energy converter development has always been hindered by the space charge.
Thermionic energy converter tec is a heat engine that generates electricity directly using heat as its source of energy and electron as its working fluid. Highly improved thermionic energy converter iopscience. Unlike the conventional indirect methods for generating electricity from heat sources, no intermediate form of energy is required, and no working fluid except the flow of the electrical charges themselvesare involved in the process. Scientists look to thermionic energy conversion for clean. Many of the people listed below also conduct research not related to energy, which is not described here. Names link to stanford employee directory listings.
Despite having a huge potential as an efficient direct energy conversion device, the progress in vacuumbased thermionic energy converter development has. The charge carriers can be electrons or ions, and in older literature are sometimes referred to as thermions. The role of defect engineering on solar energy conversion is developed, extending light absorption, promoting charge separation, and facilitating stable pc reaction. Publishers pdf, also known as version of record includes final page, issue and. It was recognized early in the 20th century that thermionic emission from a hot surface could be an efficient way to convert hightemperature thermal energy directly into electricity, 16 with practical applications in the nuclear 17 and aerospace sectors. Research was taken over by the department of mechanical engineering. Welcome to the website of the bargatin group at the university of pennsylvania. Thermionic emission is the thermally induced flow of charge carriers from a surface or over a potential energy barrier. The nuclear fuel is located in the middle of tfe and heat radiates outward. Thermionic energy conversion in the twentyfirst century. Thermionic energy conversion plasmas plasma science. Thermionic energy conversion tec is the direct conversion of heat into electricity by the mechanism of thermionic emission, the spontaneous ejection of hot electrons from a surface. Pdf thermionic energy conversion in the twentyfirst century. The iby and aladar fleischman faculty of engineering the zandmanslaner school of graduate studies photon enhanced thermionic emission for solar energy conversion a thesis submitted toward the degree of doctor of philosophy by gideon segev this research was carried out at the school of electrical engineering.
For that reason, the author developed the general theory of the plasma diode energy converter. Because of its promise, researchers have been trying for more than half a century to develop a practical thermionic generator, with little luck. Efficient thermionic emission energy harvesting is a challenging problem that scientists and engineers have pondered for decades. There is a meteorological institute, but one of the most important obninsk institutes is without doubt the institute of physics and power engineering ippe. Thermionic power generation electron distribution is fe expekbt ec, ea are working functions at cathode and anode only electrons with energy larger than working function or barrier height can flow from one electrode to another. The staff of the thermo electron engineering corporation has. The achievement of the defective photocatalysts is discussed toward versatile applications such as solar water splitting, co 2 reduction, nitrogen fixation, molecular activation. Thermoelectric, thermionic and thermophotovoltaic energy. In this letter, we provide the experimental demonstration of a hybrid thermionic photovoltaic. The efficiency of emission is sensitive to surface recombination at the interface between the gaas and algaas layer however, due to the much smaller energy barrier between the algaas and. A thermionic converter consists of a hot electrode which thermionically emits electrons over a potential energy barrier to a cooler electrode, producing a useful electric power output. Jpl1967 a cross sectional view of a thermionic fuel element tfe. Although the physical mechanism has been known for over a century, it has yet to be consistently realized in a manner practical for largescale deployment. The thermionic conversion can be utilized in several different situationsremote locations on the earth and in space.
With the potential to double the electricity output. January 22, 2015 abstract in this paper, we propose a model to investigate the electron thermionic emission from a single. Thermionic energy conversion, volume 1 the mit press. Introduction thermionic energy conversion is well suited for space applications. A thermionic energy converter tec is a static device that converts heat directly into electricity. We push the limits of nanofabrication techniques to create materials and structures with unprecedented mechanical properties and to enable applications such as heattoelectricity direct energy conversion and new levitation techniques for microflyers. Thermionic emission is the heatinduced flow of charge carriers from a surface or over a potentialenergy barrier.
This occurs because the thermal energy given to the carrier overcomes the forces restraining it. Tarakanov, users manual for code karat moscow, russia, 2000. We study thermionic cooling across goldgraphenewse2graphenegold structures computationally and experimentally. Thermionic emission is the liberation of electrons from an electrode by virtue of its temperature releasing of energy supplied by heat. Lecture 6 thermionic engines i t mit opencourseware. A thermionic converter is a static device that converts heat into electricity by boiling electrons from a hot emitter. Review on thermionic energy converters ieee journals. Performing organization names and addresses university of california,baskin school of engineering,santa cruz,ca,95064 8. Advanced energy conversion thermionic power conversion. At stanford, they were part of a worldleading research group on thermionic energy converters, focusing on a breakthrough solar conversion process based on photonenhanced thermionic energy conversion, which harvests both photon and heat energy from the suns spectrum. Photovoltaic anodes for enhanced thermionic energy conversion. Sustainable energy science and engineering center solar thermionic output voltage based on emittercollector spacing. A thermionic generator, in principle, can make use of any fuel may be fossil fuel, a nuclear fuel or solar energy subject to the condition that sufficiently high temperatures are obtainable. Frontiers thermionic energy conversion in the twenty.
The conversion efficiency and high temperature of heat rejection minimize the size and weight of the radiator. Thermionics is a method for converting heat to electricity that was developed in the 1960s and 1970s, primarily for use in the spacenuclear program. Ang1, 1sutdmit international design center, singapore university of technology and design, singapore 8682. Thermionic converter project gutenberg selfpublishing.
Thermionic energy conversion, space technology for energy. Thermionic energy conversion tec is the direct conversion of heat. Thermionic energy converters are heat engines based on the direct emission of electrons from a hot cathode towards a colder anode. Thermionic conversions is a method for converting heat directly into electrical energy. Graphene and wse2 layers were stacked, followed by.
Thermionic energy conversion based on 3d dirac semimetals. Pete combines photovoltaic based photoemission and thermionic emission processes allowing for conversion of photon energy directly to emitted electron energy, while simultaneously utilizing thermalization and photon absorption losses to drive thermionic emission from electrons excited above the emitter band gap. Thermionic energy conversion is the direct conversion of heat into electricity by the mechanism of thermionic emission, the. An analytical model is established to study the energy transfer of electrons and phonons on the basis of average values of physical properties. Go eppropulsion and power division aerospace and mechanical engineering nasa johnson space center university of notre dame october 1415, 2014 nasa johnson space center houston, tx. Closed spaced thermionic converter with isothermic. Through a process known as thermionic conversion, heat energysuch as light from the sun or heat from burned fossil fuelscan be converted into electricity with very high efficiency. Electron thermionic emission from graphene and thermionic. Us9590535b2 memsbased integrated inverter for wafer. Working as refrigerators or power generators, they are competitive to 4,5, or.
This database covers only energy related research at stanford, slac, hoover institution and the carnegie institution departments at stanford. Vacuum thermionic energy converter construction of a thermionic energy converter sulfur doped nanocrystalline diamond films as field enhancement based. In early to mid nineties several groups pointed out the advantage of electron energy filters in bulk thermoelectric materials,14,15. Since the thermionic emission is unavoidably accompanied by photonic emission, radiative energy transfer is a significant source of losses in these devices. Despite having a huge potential as an efficient direct energy conversion device, the progress in vacuumbased thermionic energy converter development has always been hindered by the space charge problem and the unavailability of materials with low work function. American institute of aeronautics and astronautics 12700 sunrise valley drive, suite 200 reston, va 201915807 703. When electrons gain sufficient energy to overcome the potential barrier, energetic electrons can escape into the vacuum under the. In 1951 it was charged with the design and construction of the worlds first nuclear power plant. The energy conversion between electrons and phonons in a heterostructure is studied for thermionic cooling based on the hot electron approximation.
Direct energy conversion global climate and energy project. Highperformance solidstate thermionic energy conversion. At stanford, they were part of a worldleading research group on thermionic energy converters, focusing on a breakthrough solar conversion process based on photonenhanced thermionic energy conversion, which harvests both photon and heat energy from the suns. A thermionic energy converter is provided that includes an anode, a cathode, where the anode is disposed opposite the cathode, and a suspension, where a first end of the suspension is connected to the cathode and a second end of the suspension is connected to the anode, where the suspension moveably supports the cathode above the anode to form a variable gap. The design of a combustion heated thermionic energy converter. Terrestrial applications of thermionic energy conversion. This treatment was first made available to interested researchers by the thermoelectron engineering corporation, and. Intersociety energy conversion engineering conference. This occurs because the thermal energy given to the carrier overcomes the work function of the material.
This slide maybe should be broken up into a general principles slide and then the experimental details slide. Caesium vapor is used to optimize the electrode work functions and provide an ion supply by surface ionization or electron impact ionization in a plasma to neutralize the electron space charge. Vacuum thermionic challenges suffer from presence of vacuum. Bargatin group university of pennsylvania department of.
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