Development of a model and computer code to describe solar grade silicon production processes. Fourth quarterly report, July 1--September 30, 1978
This program aims at developing a mathematical model, and a computer code based on this model, which will allow prediction of the product distribution in chemical reactors in which gaseous silicon compounds are converted to condensed-phase silicon. The reactors to be modeled are flow reactors in which silane or one of the halogenated silanes is thermally decomposed or reacted with an alkali metal, H/sub 2/ or H atoms. Because the product of interest is particulate silicon, processes which must be modeled, in addition to mixing and reaction of gas-phase reactants, include the nucleation and growth of condensed Si via coagulation, condensation, and heterogeneous reaction. Period mechanisms for the SiCl/sub 4//Na and SiF/sub 4//Na reaction systems were examined. Reaction schemes which include 25 elementary reactions were formulated for each system and run to test the sensitivity of the computed concentration and temperature profiles to the values given estimated rate coefficients. It was found that, for SiCl/sub 4//Na, the rate of production of free Si is largely mixing-limited for reasonable rate coefficient estimates. For the SiF/sub 4//Na system the results indicate that the endothermicities of many of the reactions involved in producing Si from SiF/sub 4//Na cause this system to be chemistry-limited rather than mixing-limited. Work is continuing on the problems of inserting particle nucleation and coagulation models into the code and is started on obtaining a suitable boundary layer code.
- Research Organization:
- Aerochem Research Labs., Inc., Princeton, NJ (USA)
- DOE Contract Number:
- NAS-7-100-954862
- OSTI ID:
- 6170099
- Report Number(s):
- DOE/JPL/954862-4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
CRYSTAL GROWTH
MATHEMATICAL MODELS
SILICON
CHEMICAL REACTORS
COMPUTER CODES
NUCLEATION
PRODUCTION
SILICON CHLORIDES
SODIUM
ALKALI METALS
CHLORIDES
CHLORINE COMPOUNDS
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
METALS
SEMIMETALS
SILICON COMPOUNDS
140504* - Solar Energy Conversion- Biomass Production & Conversion- (-1989)
360603 - Materials- Properties