New Page 1

LA GRAMMATICA DI ENGLISH GRATIS IN VERSIONE MOBILE   INFORMATIVA PRIVACY

  NUOVA SEZIONE ELINGUE

 

Selettore risorse   

   

 

                                         IL Metodo  |  Grammatica  |  RISPOSTE GRAMMATICALI  |  Multiblog  |  INSEGNARE AGLI ADULTI  |  INSEGNARE AI BAMBINI  |  AudioBooks  |  RISORSE SFiziosE  |  Articoli  |  Tips  | testi pAralleli  |  VIDEO SOTTOTITOLATI
                                                                                         ESERCIZI :   Serie 1 - 2 - 3  - 4 - 5  SERVIZI:   Pronunciatore di inglese - Dizionario - Convertitore IPA/UK - IPA/US - Convertitore di valute in lire ed euro                                              

 

 

WIKIBOOKS
DISPONIBILI
?????????

ART
- Great Painters
BUSINESS&LAW
- Accounting
- Fundamentals of Law
- Marketing
- Shorthand
CARS
- Concept Cars
GAMES&SPORT
- Videogames
- The World of Sports

COMPUTER TECHNOLOGY
- Blogs
- Free Software
- Google
- My Computer

- PHP Language and Applications
- Wikipedia
- Windows Vista

EDUCATION
- Education
LITERATURE
- Masterpieces of English Literature
LINGUISTICS
- American English

- English Dictionaries
- The English Language

MEDICINE
- Medical Emergencies
- The Theory of Memory
MUSIC&DANCE
- The Beatles
- Dances
- Microphones
- Musical Notation
- Music Instruments
SCIENCE
- Batteries
- Nanotechnology
LIFESTYLE
- Cosmetics
- Diets
- Vegetarianism and Veganism
TRADITIONS
- Christmas Traditions
NATURE
- Animals

- Fruits And Vegetables



ARTICLES IN THE BOOK

  1. AAAA battery
  2. AAA battery
  3. AA battery
  4. A battery
  5. Absorbent glass mat
  6. Alessandro Volta
  7. Alkaline battery
  8. Alkaline fuel cell
  9. Aluminium battery
  10. Ampere
  11. Atomic battery
  12. Backup battery
  13. Baghdad Battery
  14. Batteries
  15. Battery charger
  16. B battery
  17. Bernard S. Baker
  18. Beta-alumina solid electrolyte
  19. Betavoltaics
  20. Bio-nano generator
  21. Blue energy
  22. Bunsen cell
  23. Car battery
  24. C battery
  25. Clark cell
  26. Concentration cell
  27. Coulomb
  28. 2CR5
  29. Daniell cell
  30. Direct borohydride fuel cell
  31. Direct-ethanol fuel cell
  32. Direct methanol fuel cell
  33. Dry cell
  34. Dry pile
  35. Duracell
  36. Duracell Bunny
  37. Earth battery
  38. Electric charge
  39. Electric current
  40. Electricity
  41. Electrochemical cell
  42. Electrochemical potential
  43. Electro-galvanic fuel cell
  44. Electrolysis
  45. Electrolyte
  46. Electrolytic cell
  47. Electromagnetism
  48. Electromotive force
  49. Energizer Bunny
  50. Energy
  51. Energy density
  52. Energy storage
  53. Flashlight
  54. Float charging
  55. Flow Battery
  56. Formic acid fuel cell
  57. Fuel cell
  58. Fuel cell bus trial
  59. Galvanic cell
  60. Gel battery
  61. Grove cell
  62. Half cell
  63. History of the battery
  64. Hybrid vehicle
  65. Lead-acid battery
  66. Leclanché cell
  67. Lemon battery
  68. List of battery sizes
  69. List of battery types
  70. List of fuel cell vehicles
  71. Lithium battery
  72. Lithium ion batteries
  73. Lithium iron phosphate battery
  74. Lithium polymer cell
  75. LR44 battery
  76. Luigi Galvani
  77. Manganese dioxide
  78. Memory effect
  79. Mercury battery
  80. Metal hydride fuel cell
  81. Methane reformer
  82. Methanol reformer
  83. Michael Faraday
  84. Microbial fuel cell
  85. Molten carbonate fuel cell
  86. Molten salt battery
  87. Nickel-cadmium battery
  88. Nickel-iron battery
  89. Nickel metal hydride
  90. Nickel-zinc battery
  91. Open-circuit voltage
  92. Optoelectric nuclear battery
  93. Organic radical battery
  94. Oxyride battery
  95. Panasonic EV Energy Co
  96. Peukert's law
  97. Phosphoric acid fuel cell
  98. Photoelectrochemical cell
  99. Polymer-based battery
  100. Power density
  101. Power management
  102. Power outage
  103. PP3 battery
  104. Primary cell
  105. Prius
  106. Proton exchange membrane
  107. Proton exchange membrane fuel cell
  108. Protonic ceramic fuel cell
  109. Radioisotope piezoelectric generator
  110. Ragone chart
  111. RCR-V3
  112. Rechargeable alkaline battery
  113. Reverse charging
  114. Reversible fuel cell
  115. Searchlight
  116. Secondary cell
  117. Short circuit
  118. Silver-oxide battery
  119. Smart Battery Data
  120. Smart battery system
  121. Sodium-sulfur battery
  122. Solid oxide fuel cell
  123. Super iron battery
  124. Thermionic converter
  125. Trickle charging
  126. Vanadium redox battery
  127. Volt
  128. Voltage
  129. Voltaic pile
  130. Watch battery
  131. Water-activated battery
  132. Weston cell
  133. Wet cell
  134. Zinc-air battery
  135. Zinc-bromine flow battery
  136. Zinc-carbon battery

 

 
CONDIZIONI DI USO DI QUESTO SITO
L'utente può utilizzare il nostro sito solo se comprende e accetta quanto segue:

  • Le risorse linguistiche gratuite presentate in questo sito si possono utilizzare esclusivamente per uso personale e non commerciale con tassativa esclusione di ogni condivisione comunque effettuata. Tutti i diritti sono riservati. La riproduzione anche parziale è vietata senza autorizzazione scritta.
  • Il nome del sito EnglishGratis è esclusivamente un marchio e un nome di dominio internet che fa riferimento alla disponibilità sul sito di un numero molto elevato di risorse gratuite e non implica dunque alcuna promessa di gratuità relativamente a prodotti e servizi nostri o di terze parti pubblicizzati a mezzo banner e link, o contrassegnati chiaramente come prodotti a pagamento (anche ma non solo con la menzione "Annuncio pubblicitario"), o comunque menzionati nelle pagine del sito ma non disponibili sulle pagine pubbliche, non protette da password, del sito stesso.
  • La pubblicità di terze parti è in questo momento affidata al servizio Google AdSense che sceglie secondo automatismi di carattere algoritmico gli annunci di terze parti che compariranno sul nostro sito e sui quali non abbiamo alcun modo di influire. Non siamo quindi responsabili del contenuto di questi annunci e delle eventuali affermazioni o promesse che in essi vengono fatte!
  • L'utente, inoltre, accetta di tenerci indenni da qualsiasi tipo di responsabilità per l'uso - ed eventuali conseguenze di esso - degli esercizi e delle informazioni linguistiche e grammaticali contenute sul siti. Le risposte grammaticali sono infatti improntate ad un criterio di praticità e pragmaticità più che ad una completezza ed esaustività che finirebbe per frastornare, per l'eccesso di informazione fornita, il nostro utente. La segnalazione di eventuali errori è gradita e darà luogo ad una immediata rettifica.

     

    ENGLISHGRATIS.COM è un sito personale di
    Roberto Casiraghi e Crystal Jones
    email: robertocasiraghi at iol punto it

    Roberto Casiraghi           
    INFORMATIVA SULLA PRIVACY              Crystal Jones


    Siti amici:  Lonweb Daisy Stories English4Life Scuolitalia
    Sito segnalato da INGLESE.IT

 
 



BATTERIES
This article is from:
http://en.wikipedia.org/wiki/Thermionic_converter

All text is available under the terms of the GNU Free Documentation License: http://en.wikipedia.org/wiki/Wikipedia:Text_of_the_GNU_Free_Documentation_License 

Thermionic converter

From Wikipedia, the free encyclopedia

 

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. Cesium vapor is used to optimize the electrode work functions and provide an ion supply (by surface contact ionization or electron impact ionization in a plasma) to neutralize the electron space charge.

Definition

From a physical electronic viewpoint, thermionic energy conversion is the direct production of electric power from heat by thermionic electron emission. From a thermodynamic viewpoint (1)it is the use of electron vapor as the working fluid in a power-producing cycle. A thermionic converter consists of a hot emitter electrode from which electrons are vaporized by thermionic emission and a colder collector electrode into which they are condensed after conduction through the interelectrode plasma. The resulting current, typically several amperes per square centimeter of emitter surface, delivers electrical power to a load at a typical potential difference of 0.5–1 volt and thermal efficiency of 5–20%, depending on the emitter temperature (1500–2000 K) and mode of operation. Details of the history, science and technology of thermionic energy conversion can be found in books on the subject (2, 3).The summary here is brief but more current.

History

After the first demonstration of the practical arc-mode cesium vapor thermionic converter by V. Wilson in 1957, several applications of it were demonstrated in the following decade, including its use with solar, combustion, radioisotope and nuclear reactor heat sources. The application most seriously pursued, however, was the integration of thermionic nuclear fuel elements directly into the core of nuclear reactors for production of electrical power in space (4, 5). The exceptionally high operating temperature of thermionic converters, which makes their practical use difficult in other applications, gives the thermionic reactor decisive advantages over competing energy conversion technologies in the space power application where radiant heat rejection is required. Substantial thermionic space reactor development programs were conducted in the U.S., France and Germany in the period 1963-1973, and the US resumed a significant thermionic nuclear fuel element development program in the period 1983-1993.

A massive thermionic reactor development program was conducted continuously in the USSR throughout the period 1960-1989, during which a full-scale thermionic reactor system was developed and first tested in 1972. Two thermionic reactor power systems (TOPAZ) were orbited and operated in space in 1988-1989.

Although the priority for thermionic reactor use diminished as the US and Russian space programs were curtailed, research and technology development in thermionic energy conversion have continued. In recent years technology development programs for solar-heated thermionic space power systems were conducted. Prototype combustion-heated thermionic systems for domestic heat and electric power cogeneration, and for rectification, have been developed (6).

Description

The scientific aspects of thermionic energy conversion primarily concern the fields of surface physics and plasma physics. The electrode surface properties determine the magnitude of electron emission current and electric potential at the electrode surfaces, and the plasma properties determine the transport of electron current from the emitter to the collector. All practical thermionic converters to date employ cesium vapor between the electrodes, which determines both the surface and plasma properties. Cesium is employed because it is the most easily ionized of all stable elements.

The surface property of primary interest is the work function, which is the barrier that limits electron emission current from the surface and essentially is the heat of vaporization of electrons from the surface. The work function is determined primarily by a layer of cesium atoms adsorbed on the electrode surfaces (7). The properties of the interelectrode plasma are determined by the mode of operation of the thermionic converter (8). In the ignited (or “arc”) mode the plasma is maintained via ionization internally by hot plasma electrons (~ 3300 K); in the unignited mode the plasma is maintained via injection of externally-produced positive ions into a cold plasma; in the hybrid mode the plasma is maintained by ions from a hot-plasma interelectrode region transferred into a cold-plasma interelectrode region.

Recent work

All the applications cited above have employed technology in which the basic physical understanding and performance of the thermionic converter were essentially the same as those achieved before 1970. During the period 1973-1983, however, significant research on advanced low-temperature thermionic converter technology for fossil-fueled industrial and commercial electric power production was conducted in the US, and continued until 1995 for possible space reactor and naval reactor applications. That research has shown that substantial improvements in converter performance can be obtained now at lower operating temperatures by addition of oxygen to the cesium vapor (9, 10), by suppression of electron reflection at the electrode surfaces (11), and by hybrid mode operation. Similarly, improvements via use of oxygen-containing electrodes have been demonstrated in Russia along with design studies of systems employing the advanced thermionic converter performance (12).

See also

  • Atomic battery
  • Betavoltaics
  • Optoelectric nuclear battery
  • Radioisotope piezoelectric generator
  • Radioisotopic Thermoelectric Generator

Reference

1. N. S. Rasor, "Thermionic energy converter," in Fundamentals Handbook of Electrical and Computer Engineering, vol. II, S.S.L. Chang., Ed., New York: Wiley, 1983, p. 668.

2. G. N. Hatsopoulos and E. P. Gyftopoulos, Thermionic Energy Conversion, vol. I, (1973); vol II, (1979); MIT Press, Cambridge, MA.

3. F.G. Baksht, et al., Thermionic Converters and Low-Temperature Plasma, Russian Edition (B. Moyzhes and G. Pikus, Eds), Acad. of Sciences USSR, Moscow, 1973. English Edition (L.K.Hansen, Ed.) available as DOE-tr-1 from NTIS, Springfield, VA.

4. J. Mills and R. Dahlberg, “Thermionic Systems for DOD Missions”, Proc. 8th Symp. on Space Nucl. Power Syst., (Albuquerque, NM), pt.3, p. 1088.

5. G. M. Griaznov, et al., “Thermoemission Reactor-Converters for Nuclear Power Units in Outer Space”, Atomnaya Energiya 66, 371-383 (1989); English translation available from Plenum.

6. E. van Kemenade & W. B. Veltkamp, “Design of a Thermionic Converter for a Domestic Heating System”, Proc. 29th Intersoc. Energy Conv. Eng. Conf., Vol. 2, p1055 (1994). Also see V.I. Yarygin, Ye. A. Meleta, V.V. Klepikov, V.A. Ruzhnikov, & L.R. Wolff, “Test of a TEC-Module”, ibid, p1061.

7. N. S. Rasor and C. Warner, “Correlation of Emission Processes for Adsorbed Alkali Films on Metal Surfaces”, J. Appl. Phys. 35, 2589 (1964).

8. N. S. Rasor, “Thermionic Energy Conversion Plasmas”, IEEE Trans. Plasma Sci., 19, 1191 (1991); invited review.

9. N.S. Rasor, “Physical-Analytical Model for Cesium/Oxygen Coadsorption on Tungsten”, Proc. 27th Intersoc. Energy Conv. Eng. Conf., Vol.3, p3.529 (1992).

10. J-L. Desplat, L.K. Hansen, G.L. Hatch, J.B. McVey and N.S. Rasor, “HET IV Final Report”, Volumes 1 & 2, Rasor Associates Report #NSR-71/95/0842, (Nov. 1995); performed for Westinghouse Bettis Laboratory under Contract # 73-864733; 344 pages. Also available in total as C.B. Geller, C.S. Murray, D.R. Riley, J-L. Desplat, L.K. Hansen, G.L. Hatch, J.B. McVey and N.S. Rasor, “High-Efficiency Thermionics (HET-IV) and Converter Advancement (CAP) programs. Final Reports”, DOE DE96010173; 386 pages (1996).

11. N.S. Rasor, “The Important Effect of Electron Reflection on Thermionic Converter Performance”, Proc. 33rd Intersoc. Energy Conv. Engr. Conf., Colorado Springs, CO, Aug., 1998, paper 98-211.

12. V. Yarygin, et al., “Energy Conversion Options For NASA’s Space Nuclear Power Systems Initiative – Underestimated Capability Of Thermionics”, Proc. 2nd International Energy Conversion Engineering Conference, Providence, RI, Aug. 2004.

Retrieved from "http://en.wikipedia.org/wiki/Thermionic_converter"