From a physical electronic viewpoint, thermionic energy conversion is the direct production of electric power from heat by thermionic electron emission. Another method for the conversion of heat to electricity is known as the thermionic energy convertor tic, for which electrons are evaporated from a heated cathode into a vacuum and then condensed at a cooler anode 20. Theoretical studies of thermionic conversion of solar energy. Pdf thermionic energy conversion tec is the direct conversion of heat into electricity by the mechanism of thermionic emission, the. Electron thermionic emission from graphene and thermionic energy converter shijun liang1 and l. In this letter, we provide the experimental demonstration of a hybrid thermionicphotovoltaic device that. Thermionic conversions is a method for converting heat directly into electrical energy. It is known that graphene can withstand temperatures as high as 4600 k in vacuum, and it has been shown that its work function can be engineered from a high value for monolayerbilayer of 4. Rohsenow heat and mass transfer laboratory, mit direct thermaltoelectric energy conversion technologies thermoelectric converter thermionic converter. Criticalpath definition for combustion augmentation with thermionic energy conversion catec james f. A thermionic converter consists of a hot electrode which thermionically emits electrons over a. Thermionic energy conversion how is thermionic energy.
This beneficial technical effect is achieved by internal distribution of tiny shorted cesium diodes driven by the thermal gradient between the primary emitter. Pdf current status of thermionic conversion of solar energy. Request pdf thermionic energy conversion the concept of a vacuum thermoelement is attractive as it removes one of the problems in thermoelectric energy conversion, namely heat conduction. With increased interest in maximizing the efficiency of present energy conversion systems, it is an important reference for scientific and engineering libraries as well. Despite having a huge potential as an efficient direct energy conversion device, the progress in vacuumbased thermionic energy converter development has. Ang1, 1sutdmit international design center, singapore university of technology and design, singapore 8682.
Review articles current status of thermionic conversion of. Evolution of thermionic energy conversion technology the earlier idea of converting heat to electrical energy via thermionic energy was first conceived by schlichter in 1915 ref. Lecture 6 thermionic engines i t mit opencourseware. This occurs because the thermal energy given to the carrier overcomes the work function of the material.
The conversion efficiency and high temperature of heat rejection minimize the size and weight of the radiator. Surface photovoltageinduced ultralow work function material. Thermionic energy conversion is intended for scientists and engineers working in the field of energy conversion. Later, in 2010, an innovative thermionic conversion mechanism called photon en hanced thermionic emission pete was put forward, which exhibits a. Electron thermionic emission from graphene and thermionic. T1 enhanced thermionic energy conversion and thermionic emission from doped diamond films through methane exposure.
A thermionic converter is a static device that converts heat into electricity by boiling electrons from a hot emitter. In this letter, we provide the experimental demonstration of a hybrid thermionic photovoltaic device that. Unlike the conventional indirect methods for generating electricity from. Nearfield enhanced thermionic energy conversion for. Sustainable energy science and engineering center direct energy conversion.
Submonolayer coatings of alkali metals have proven to significantly reduce the work function. A thermionic converter consists of a hot emitter electrode from which electrons. Thermionic converter article about thermionic converter by. Us3436566a us3436566da us3436566a us 3436566 a us3436566 a us 3436566a us 3436566d a us3436566d a us 3436566da us 3436566 a us3436566 a us 3436566a authority us united states prior art keywords energy converter space caesium thermionic energy electrode prior art date 19650225 legal status the legal status is an assumption and is not a legal conclusion. A new study indicates that heat temperature can be lowered by an order of magnitude if using graphene. Much effort has been put into finding thermally stable material combinations that exhibit low work functions. Impact microscaleenhanced, photonenhanced thermionic emitters enable highefficiency solartoelectrical conversion by taking advantage of hightemperature, solidstate energy production. Dec 03, 20 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. The goal is to achieve direct thermal to electric energy conversion with.
This invention is concerned with improving the efficiency of thermionic energy converters. Thermionic power converter, any of a class of devices that convert heat directly into electricity using thermionic emission rather than first changing it to some other form of energy. A thermionic converter is a device which converts heat energy into electrical energy by utilizing the thermionic emission of electrons. Thermionic energy conversion tec is the direct conversion of heat into electricity by the mechanism of thermionic emission, the spontaneous. Significant research interest is currently focused on the thermionic conversion of heat energy to electrical energypower using thermionic energy converter tec. The nuclear fuel is a ceramic composition of fissionable material in a metal matrix. The charge carriers can be electrons or ions, and in older literature are sometimes referred to as. Photovoltaic anodes for enhanced thermionic energy conversion. Solidstate and vacuum thermionic energy conversion dtic. Thermoelectric, thermionic and thermophotovoltaic energy. Thermionic energy conversion \ pdf renewable technologies.
January 22, 2015 abstract in this paper, we propose a model to investigate the electron thermionic emission from a single. The invention is particularly directed to the reduction of plasma losses in these converters. Microscaleenhanced, photonenhanced thermionic emitters enable highefficiency solartoelectrical conversion by. A programmanagement plan with criticalpath definition for. Thermionic energy conversion, volume 1 the mit press. A brief overview of the research activities at the thermionic energy conversion tec center is given. The simplest type of thermionic converter consists of two electrodes separated by a vacuum gap a simple cesium thermionic converter is shown in figure 1 on page 604.
Thermionic energy conversion by mohammad islam lap lambert acad. Surface photovoltageinduced ultralow work function. Thermionic energy converters have been used with different heat sources, all of them requiring operation at high temperatures above 1500 k. Diamond based isothermal photonenhanced thermionic solar. Consequently, thermionic systems with high powertoweight ratios are possible. A thermionic energy converter using singlelayer graphene. Innovative energy conversion technologies, such as lowtemperature thermionic conversion and multiple thermionic conversion 31, 32 might be useful in the harvest of waste heat. Thermionic energy conversion tec using nanomaterials is an emerging field of research. Compared with te based convertor tec, tic normally operates at high temperature. Pdf thermionic energy conversion in the twentyfirst century. One of these is raised to a sufficiently high temperature to.
Thermionic energy conversion system free download as powerpoint presentation. Heat energy can be converted into electricity with very high efficiency through a temperatureinduced electron flow process known as thermionic emission. The design of a combustion heated thermionic energy converter. Thermionic energy conversion in the twentyfirst century. Low work function materials are essential for efficient thermionic energy converters tecs, electronics, and electron emission devices. The goal is to achieve direct thermal to electric energy conversion with 20% efficiency and 1wcm2 power density at a hot side temperature of 300650c. Thermionic energy conversion is well suited for space applications. Thermionic conversion is a method for converting heat directly into electrical energy. Design of a thermionic converter for a domestic heating system pdf.
Efficiency and cop in vacuum diodes used as energy convertors. Roadmap of thermionic energy conversion for concentrating solar power is brought forward. Thermionic energy conversion for concentrating solar power. The basic plasma types associated with various modes of con. Pdf recent advances in science and technology of materials fabrication, engineering of work functions, and micrometer gap machining between emitter. Morris national aeronautics and space administration lewis research center cleveland, ohio 445 owen s. Abstract concentrating solar power csp is a mainstream of solar energy utilization, and thermionic emission is a potential way to convert concentrated solar radiation into power with a theoretical efficiency of 5070%, surpassing both shockleyqueisser. This chapter focuses on the thermionic energy conversion with description of idealized model of a thermionic converter and work function of various surfaces. With the potential to double the electricity output.
The concept of a vacuum thermoelement is attractive as it removes one of the problems in thermoelectric energy conversion, namely heat conduction through a solid. May 14, 2014 title diamond based isothermal photonenhanced thermionic solar energy conversion topping devices, abstract photonenhanced thermionic emission pete is a process that harnesses both the light and heat of the sun to generate electricity and increases the efficiency of solar power production by more than twice the current levels. From a thermodynamic viewpoint, it is the use of electron vapor as the working fluid in a powerproducing cycle. Thermionic energy converters are heat engines based on the direct emission of electrons from a hot cathode toward a colder anode. Thermionic energy conversion is the direct conversion of heat into electricity by the mechanism of thermionic emission, the spontaneous ejection of hot electrons. Enhanced thermionic energy conversion and thermionic emission. Advanced energy conversion thermionic power conversion. Scientists look to thermionic energy conversion for clean and. Unlike the conventional indirect methods for generating electricity from heat sources, no intermediate form of energy is required, and no working fluidexcept the flow of the electrical charges themselvesare involved in the process. Direct energy conversion by reiner decher,oxford university press, 1997. A thermionic device for converting nuclear energy into electrical energy comprising a tubular anode spaced from and surrounding a cylindrical cathode, the cathode having an outer emitting surface of ruthenium, and nuclear fuel on the inner cylindrical surface. Thermionic emission in both vacuum and solidstate devices is investigated. Thermionic energy conversion plasmas plasma science, ieee.
Thermionic emission is the liberation of electrons from an electrode by virtue of its temperature releasing of energy supplied by heat. Neuware thermionic energy converter tec is a device to generate electricity from heat in a. The charge carriers can be electrons or ions, and in older literature are sometimes referred to as thermions. It is shown that efficient thermionic generation in a vacuum device might be possible if improved thermionic emitters become available. Because the thermionic emission is unavoidably accompanied by photonic emission, radiative energy transfer is a significant source of losses in these devices. Highly improved thermionic energy converter iopscience.
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