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Modeling of a supersonic DC plasma t...

Guo, Liping.

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Modeling of a supersonic DC plasma torch system for carbon nanotube production.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Modeling of a supersonic DC plasma torch system for carbon nanotube production./
作者:	Guo, Liping.
面頁冊數:	167 p.
附註:	Source: Dissertation Abstracts International, Volume: 71-05, Section: B, page: 3198.
Contained By:	Dissertation Abstracts International71-05B.
標題:	Engineering, Chemical. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NR61884
ISBN:	9780494618844

Modeling of a supersonic DC plasma torch system for carbon nanotube production.
Guo, Liping.

Modeling of a supersonic DC plasma torch system for carbon nanotube production. - 167 p.

Source: Dissertation Abstracts International, Volume: 71-05, Section: B, page: 3198.

Thesis (Ph.D.)--McGill University (Canada), 2009.

The carbon nanotube (CNT) structure forms a very promising source material. It has unique properties such as high thermal and electrical conductivities, and a very high mechanical strength. In recent years, researchers were able to improve both the quantity and quality of the CNT production. Among the efforts made to scale up the production, Harbec and Meunier designed a new plasma torch process for the industrial production of CNT in bulk powder form. Their process is based on the DC plasma-jet pyrolysis of a carbon-containing gas. Experiments were conducted using either 100 slpm of argon or 225 slpm of helium. Tetrachloroethylene (C2Cl4, or TCE) was selected as the carbon raw material. The present work focuses on the modeling of this CNT synthesis process and aims at an understanding of the physical and chemical phenomena observed in this system. First, a description is made of the temperature and flow fields, as well as the species concentration distribution in the torch nozzle using both possibilities of He or Ar as the plasma gas. This is followed in the second part of the thesis by a model aimed to study the nucleation and evolution of the metal particles acting as catalyst for CNT growth in the nozzle. In the third part, the modeling of the TCE pyrolysis process in the flow was carried out.

ISBN: 9780494618844Subjects--Topical Terms:

1018531
Engineering, Chemical.

Modeling of a supersonic DC plasma torch system for carbon nanotube production.
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245 1 0 $a Modeling of a supersonic DC plasma torch system for carbon nanotube production.
300 $a 167 p.
500 $a Source: Dissertation Abstracts International, Volume: 71-05, Section: B, page: 3198.
502 $a Thesis (Ph.D.)--McGill University (Canada), 2009.
520 $a The carbon nanotube (CNT) structure forms a very promising source material. It has unique properties such as high thermal and electrical conductivities, and a very high mechanical strength. In recent years, researchers were able to improve both the quantity and quality of the CNT production. Among the efforts made to scale up the production, Harbec and Meunier designed a new plasma torch process for the industrial production of CNT in bulk powder form. Their process is based on the DC plasma-jet pyrolysis of a carbon-containing gas. Experiments were conducted using either 100 slpm of argon or 225 slpm of helium. Tetrachloroethylene (C2Cl4, or TCE) was selected as the carbon raw material. The present work focuses on the modeling of this CNT synthesis process and aims at an understanding of the physical and chemical phenomena observed in this system. First, a description is made of the temperature and flow fields, as well as the species concentration distribution in the torch nozzle using both possibilities of He or Ar as the plasma gas. This is followed in the second part of the thesis by a model aimed to study the nucleation and evolution of the metal particles acting as catalyst for CNT growth in the nozzle. In the third part, the modeling of the TCE pyrolysis process in the flow was carried out.
520 $a The fluid dynamics equations are used in this system showing supersonic characteristics. A realizable k-&egr; model is used to address the turbulent effects in the flow fields. The moment method is employed to calculate the formation of the fine catalyst particles from the metal vapor injected. Within the supersonic domain of the flow field, the influence of existing shock waves on the particle nucleation is discussed, as well as the chemical reactions involved. Results show that the supersonic phenomena make it possible for metal particles to nucleate and be maintained in small sizes. This however also causes a backflow in the nozzle, which partially contributes to the experimentally observed soot deposition and CNT growth within the nozzle. The carbon containing gas experiences a fast dissociation process once it enters the nozzle. The produced carbon species are maintained in small clusters of carbon atoms in the high temperature environment within the nozzle. These clusters and atoms serve as the source of CNT growth and form a layer of carbon deposit on the surface of the nozzle. This deposited layer acts as a thermal insulator changing the conditions in the nozzle, particularly on the wall. A modeling of this effect is performed, confirming that the basic requirements for CNT growth are attained within the nozzle itself.
520 $a A parametric study of the process is carried out and suggestions are made on the geometry of the reactor and the operating parameters for the formation of CNT. These modeling results suggest that the process can be optimized with carefully chosen operating parameters. With the specific design of the nozzle used here, it is recommended to operate at lower pressures in the reactor in order to avoid a backflow in the nozzle. Different kinds of metal catalyst can be used in this system and the reactor length should be adjusted accordingly in order to optimize the outcome of the process.
590 $a School code: 0781.
650 4 $a Engineering, Chemical. $3 1018531
650 4 $a Physics, Fluid and Plasma. $3 1018402
650 4 $a Engineering, Materials Science. $3 1017759
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710 2 $a McGill University (Canada). $b Department of Chemical Engineering. $3 1678219
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791 $a Ph.D.
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