Thermionic power converter thermionic power converter major types of thermionic converters. A thermionic energy converter using singlelayer graphene nanowerk spotlight heat energy can be converted into electricity with very high efficiency through a temperatureinduced electron flow process known as thermionic emission. Updated 32014 investigation of miniaturized radioisotope thermionic power generation for general use adam j. A thermionic converter consists of a hot emitter electrode from which electrons. From a thermodynamic viewpoint, it is the use of electron vapor as the working fluid in a powerproducing cycle. Thermionic energy conversion for concentrating solar power. Pdf general overview of thermionic power generation. Because the accelerating electrons constitute a steady current i. In this article we will discuss about the construction and working of thermionic generator with the help of a suitable diagram. Pdf solidstate and vacuum thermionic energy conversion. Scientists look to thermionic energy conversion for clean and efficient power generation.
A thermionic converter was a device used in the power distribution facility on quarra. Thermionic emission 103 where vx is the potential di. These features enables many possible applications for thermionic power generation and thermionic cooling. Having established a theoretical basis for thermionic and photoexcited electron emission, we now turn attention to practical functions enabled by such processes. Download pdf gas turbine power generation book full free. In the case of thermionic emission we observe emitted electrons from a metal due to its high temperature. The book is interspersed with solved problems for a sound. We believe that the present work provides a theoretical framework for submicrongap thermionic power generation as a promising energy recycling scheme for highquality heat sources. Thermionic energy conversion tec is the direct conversion of heat into electricity by the mechanism of thermionic emission, the spontaneous. The basic operating principle of thermionic energy converters is that electrons are evaporated from a heated. Thermionic definition is relating to, using, or being the emission of charged particles such as electrons by an incandescent material. Pdf gas turbine power generation download full pdf. A thermionic generator of electricity is essentially a diode. Gas turbine power generation available for download and read online in other formats.
Thermionic emission must not be confused with thermic emission of black body for example where photons are emitted from heated body. An integrated solar upper stage isus provides orbital transfer capabilities, power generation for payloads, and. Roadmap of thermionic energy conversion for concentrating solar power is brought forward. The available power and the efficiency of a thermionic converter can be severely limited by buildup of space charge between the electrodes. The converter may be used as an electrical power generator or hightemperature sensor in space, airborne, ground, or subsurface. In one example embodiment, a power generation system for an aircraft includes a thermionic generator arranged to receive heat from at least one heat source. A device for converting heat into electricity through the use of thermionic emission and no working. Power management and distribution system developed for thermionic power converters. In its most elementary form, a thermionic converter consists of two. Older seebeckbased devices used bimetallic junctions and were.
This version of thermionic power conversion is called thermoelectronic power generation, as it is independent of the emission mechanism and furthermore uses only electrons, no ions, as active particles meir et al. A spacecraft solar, bimodal system combines propulsion and power generation into a single integrated system. 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. Revisiting submicrongap thermionic power generation based. Choi investigation of miniaturized radioisotope thermionic power generation for general use, proc.
Thermoelectric power generator ppt pdf seminar report. An elementary thermionic generator, or thermionic converter, consists of a hot metal surface emitter separated from a cooler electrode collector by an insulator seal. Here, we report a device that overcomes both of the above challenges and lays the foundation for compact thermionic solar cells. The devices used for thermionic power generation are thermionic converters which have been. The slacstanford university research team is creating a new solidstate energy conversion technology based on microfabricated and photonenhanced thermionic energy converters ptecs. Solidstate and vacuum thermionic energy conversion. Frontiers thermionic energy conversion in the twenty. Adequate power supply is an unavoidable prerequisite to any nations development and electricity generation, transmission and distribution are capital intensive activities requiring huge resources of both funds and capacity.
The generator also has a collector 23 positioned about the grouped emitters and spacers a selected distance from the emitters. A thermionic convertergenerator comprises a heated cathode electron emitter and an anode electron collector separated by vacuum, the electrical output circuit being connected between the two as shown in the fig. Thermionic energy converters utilizing nuclear fuel as a heating source for the emittercollector assembly and the general operation thereof are known. For thermionic power generation, we would like to have barrier thickness to be on the order of the electron meanfreepath. Comparison both thermionic and thermoelectric generators employ the electron gas as the working fluid a thermionic generator based on the ballistic current flow which is highly efficient, and its theoretical efficiency is close to the carnot efficiency a thermoelectric generator, however, has poor efficiency due to the diffusive. A thermionic generator 10 has a heated metal heat tube 11 journaled through a set of starshaped emitters 12 and a set of electrically insulative spacers. One of these is raised to a sufficiently high temperature to. The proposed nearfield enhanced thermionic energy conversion netec system is uniquely configured with a lowbandgap semiconductor cathode separated from a thermal emitter with a subwavelength gap.
In such a system electrons are boiled off an emitting electrode, the cathode, by heating it, and collected by a second electrode, the anode, placed nearby. Thermionic emission in vacuum could be a highly efficient cooler or power generator if the work function, the minimum work for electrons to go into vacuum, is around 0. I dismantled it after a slightly disappointing period of testing and made another version using an 812a triode. Solidstate and vacuum thermionic energy conversion a. Frontiers thermionic and photoexcited electron emission. This picture shows an 8 based hartley oscillator transmitter being tested with a makeshift power supply. Thermionic and thermoelectric power generators mona zebarjadi arpae workshop. A device for converting heat into electricity through the use of thermionic emission and no working fluid other than electric charges.
Thermionic energy converters are uniquely suited for such topping cycle applications because of their high operating temperatures. Nuclearthermionic systems may be of use for specialpurpose power sources e. In this important intermediate transport regime, it is not easy to calculate. Publishers pdf, also known as version of record includes final page, issue and. A thermionic energy converter using singlelayer graphene. Investigation of miniaturized radioisotope thermionic. 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. Power management and distribution system developed for. Magneto hydro dynamic mhd or hydro dynamics is the academic discipline which studies the dynamics of. A thermionic converter generator comprises a heated cathode electron emitter and an anode electron collector separated by vacuum, the electrical output circuit being connected between the two as shown in the fig. Thermionic power generator accessscience from mcgrawhill.
An electrically charged particle, especially an electron, emitted by a conducting material at high temperatures. Thermionicthermoelectric generator system and apparatus james. Pdf thermionic energy converter tec is a heat engine that generates electricity. The basic principle of thermionic power generation is the same as that of the thermionic valve once before the advent of transistors at the heart of all electronic equipment. From a physical electronic viewpoint, thermionic energy conversion is the direct production of electric power from heat by thermionic electron emission. When used as a topping cycle in concentrated solar thermal electricity generation, ptecs will enable system efficiencies in excess of 50%. New highly efficient thermoelectronic generator by american institute of physics this is a view into the test generator, looking at the emitter 3 cm diameter.
Electric field concentration due to engineered surface roughness is also examined as a potential approach to produce an additional increase in power generation. Direct power generation using tunneling and thermionic. In 2377, chakotay, while investigating the apparent brainwashing of the uss voyager crew on quarra in the guise of amal kotay, was. Users may download and print one copy of any publication from the public portal. A thermionic converter is a static device that converts heat into electricity by boiling electrons from a hot emitter. Thermionic converterdirect electricity generation youtube. Thermoelectric, thermionic and thermophotovoltaic energy. The design of a combustion heated thermionic energy converter. If illuminated by even a lowpower laser beam that is focused sufficiently, a spot on the forest sidewall. Systems and methods for power generation for an aircraft are provided. Recently, we observed a heat trap effect in a macroscopicsize array of verticallyaligned carbon nanotubes, known as a carbon nanotube forest.
Introduction mhd power generation is a direct energy conversion,which converts the heat energy directly into electrical energy without any intermediate mechanical energy conversion. Scientists look to thermionic energy conversion for clean. Thermionic energy conversion tec is the direct conversion of heat into. This occurs because the thermal energy given to the carrier overcomes the work function of the material. Terrestrial applications of thermionic energy conversion. The thermionic generator is configured to generate electrical power for one or more aircraft systems based at least in part on the heat received from the at least one. Nuclearthermionic systems are also of interest to nuclear centralstation power generation as a topper for a conventional steam turbine. The vacuum type of thermionic converter uses a very small gap between its emitter and collector electrodestypically 0. Applications of electron emission have often been motivated by power generation applications and, to a lesser extent, refrigeration westover, 2008.
Thermionic energy conversion in the twentyfirst century. Thermionic definition of thermionic by merriamwebster. Despite having a huge potential as an efficient direct energy conversion device, the progress in vacuumbased thermionic energy. In this manuscript, we develop an analytical model to investigate the. Thermionic power converter major types of thermionic. Mobile electrons in metals, also called valence electrons, are responsible for electric current. A thermionic converter is a static device that converts heat into electricity by boiling electrons from a hot emitter surface. The thorium dispersion enhances thermionic electron emission, which in turn improves the starting characteristics of gas tungsten arc welding electrodes.
Electron emission from a solid can be achieved through. A simplified description of the thermionic converter and its operating principles are presented to provide a basis for the discussion of thermionic converter applications. Nuclear thermionic systems are also of interest to nuclear centralstation power generation as a topper for a conventional steam turbine. Choib anational institute of aerospace, 100 exploration way, hampton, va, 23666. Nuclear thermionic systems may be of use for specialpurpose power sources e. Thermionic energy conversion is a process that converts heat directly into electrical power. This article proposes a new energy harvesting concept that greatly enhances thermionic power generation with high e ciency by exploiting the near field enhancement of thermal radiation.
Thermionic definition of thermionic by the free dictionary. On this channel you can get education and knowledge for general issues and topics. Review on thermionic energy converters article pdf available in ieee transactions on electron devices april 2016 with 2,675 reads how we measure reads. Electricity can be generated by the thermionic effect, that is, the use of dissimilar metals can cause electrons to flow in the presence of heat. They operated on a rotating frequency and so had to be closely monitored. Apparatus is disclosed including a compact thermionic generator formed with an outer cathode. Advanced energy conversion thermionic power conversion. Thermoelectric and thermionic generators slideshare. Solidstate thermionic power generators are an alternative to thermoelectric modules. Thermionic power generator accessscience from mcgraw. The interelectrode gap is usually a fraction of a millimeter in width. The charge carriers can be electrons or ions, and in older literature are sometimes referred to as thermions.