Numerical Study of Low- and High-Temperature Silane Combustion.
Numerical Study of Low- and High-Temperature Silane
Combustion.
(920 K)
Babushok, V. I.; Tsang, W.; Burgess, D. R. F., Jr.;
Zachariah, M. R.
Combustion Institute, Symposium (International) on
Combustion, 27th. Proceedings. Volume 2. August 2-7,
1998, Boulder, CO, Combustion Institute, Pittsburgh, PA,
2431-2439 pp, 1998.
Keywords:
combustion; high temperature; silanes; computer
simulation; autoignition; flame propagation
Abstract:
Self-ignition and flame propagation properties of silane
combustion systems have been studied through computer
simulations using a database of kinetic and
thermodynamic information that is consistent with
current understanding of the elementary processes. These
new inputs include the mechanism for chain branching
through the SiH3 radical, rate constants for the
reactions of HO2 with silane and its breakdown products,
and the reaction of SiO with oxygen. Over the entire
temperature range, the simulations show two distinct
mechanisms. At low temperatures, the kinetics of SiH3 is
controlling, whereas at high temperatures, SiH3
chemistry is of key importance. The results demonstrate
that the upper explosion limit and ignition at room
temperature and 1 bar can be described by the same set
of reactions. With the new database, many of the
experimental observations can be reproduced, and
predictions are made regarding dependencies on process
parameters. These include the critical conditions for
chain ignition, the dependence of the critical pressure
on the ratio of silane and oxygen concentration, and the
temperature dependence of the critical ratio of silane
to oxygen concentration. A scenario for low-temperature
ignition is presented. At high temperatures, the
importance of condensation processes for accurate
prediction of flame velocities is clear. For very lean
flames, the maximum reaction rate occurs at the lower
temperature region of the flame zone.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899