Modelling of ethanol pyrolysis in a commercial CVD reactor for growing carbon layers on alumina substrates
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Автор:
Andrey V. Minakov
Mikhail M. Simunin
Ilya I. Ryzhkov
Коллективный автор:
Институт цветных металлов и материаловедения
Институт космических и информационных технологий
Кафедра композиционных материалов и физико-химии металлургических процессов
Кафедра прикладной математики и компьютерной безопасности
Дата:
2019-12Журнал:
International Journal of Heat and Mass TransferКвартиль журнала в Scopus:
Q1Квартиль журнала в Web of Science:
Q1Библиографическое описание:
Andrey V. Minakov. Modelling of ethanol pyrolysis in a commercial CVD reactor for growing carbon layers on alumina substrates [Текст] / Andrey V. Minakov, Mikhail M. Simunin, Ilya I. Ryzhkov // International Journal of Heat and Mass Transfer. — 2019. — Т. 145.Аннотация:
Chemical vapour deposition (CVD) is widely used for preparation of pyrolytic carbons from various precursors.
The prediction of deposition kinetics requires deep understanding of all transport phenomena
involved. In this work, we perform the computational modelling of ethanol pyrolysis in a commercial
CVD reactor (a tube furnace). The reactor is employed for growing carbon layers on alumina substrates.
The inlet gas flow is produced by evaporating azeotrope ethanol/water mixture and mixing it with inert
gas (argon). The modelling is performed in 3D and 2D statements using Marinov mechanism with 57 species
participating in 383 reactions. The heat and species transport is taken into account with temperature
dependent physical properties. It is shown that the inlet gas velocity in the 2D statement should be corrected
for a meaningful comparison with the 3D case. A good agreement is found between species mole
fractions at the substrate position for 3D and 2D statements at low volume flow rates, while at high flow
rates some deviations are observed. The temperature at the substrate position is found to be lower than
at the reactor wall due to inflow of a colder gas. The main pyrolysis products at moderate temperatures
(around 900 C) are water, ethylene, hydrogen, carbon monoxide, and methane. With increasing temperature,
the mole fractions of hydrogen, acetylene, and carbon monoxide increase, while those of water and
methane become smaller. With increasing ethanol/water volume flow rate, the mole fractions of ethanol
and pyrolysis products saturate at some constant values due to incomplete thermal decomposition of
ethanol in the reactor volume. The rise of argon flow rate leads to the decrease of pyrolysis products mole
fractions due to decrease of residence time. The obtained results can be employed for simulating and analyzing
pyrolysis processes in realistic CVD reactors with complex geometry as well as for the development
of coupled gas phase and surface reaction model of carbon layer deposition on nanoporous
substrates.