RTP Modeling for CVD and Thermal Oxidation

1994 ◽  
Vol 342 ◽  
Author(s):  
F.Y. Sorrell ◽  
M.J. Fordham ◽  
Seungil Yu ◽  
A.J. Silva Neto
Keyword(s):  
Heat Transfer ◽  
Film Thickness ◽  
Thermal Oxidation ◽  
Process Model ◽  
Gas Flow ◽  
Temporal Distribution ◽  
Chemical Vapor ◽  
Radiant Heat ◽  
Radiant Heat Transfer ◽  
Parallel Diffusion

ABSTRACTA methodology for predicting the spatial and temporal distribution of film thickness is given for Chemical Vapor Deposition (CVD), and for thermal oxidation in Rapid Thermal Processor (RTP) systems, e.g. RTPCVD and RTO. The methodology is based on a wafer thermal model for the heat transfer to, from and within the wafer, a geometric ray trace algorithm to predict the radiant heat transfer from the lamps and reflectors to the wafer, a process model for the deposition or oxidation, and a gas flow model to predict the flow field in the RTP chamber. The CVD process is based on the Arrhenius deposition model, and thermal oxidation is based on a parallel diffusion model. The methodology has been validated by comparison of measured and predicted final film thickness from a cylindrical RTP system. The methodology is based on physical principles, with a minimum reliance on empirical relations and experimental data. As such it can be used for optimization of existing RTP designs and for the evaluation of proposed RTP configurations, such as new or novel lamp, reflector or chamber geometry.

Mathematical modelling of woody particles pyrolysis in a fixed bed

2019 ◽  
pp. 14-24
Author(s):  
Игорь Геннадьевич Донской
Keyword(s):  
Heat Transfer ◽  
Single Particle ◽  
Power Plants ◽  
Gas Flow ◽  
Fixed Bed ◽  
Radiant Heat ◽  
Heat Fluxes ◽  
Radiant Heat Transfer ◽  
Particle Layer ◽  
Wood Particles

Рассмотрена задача термического разложения совокупности последовательно расположенных древесных частиц с учетом внешнего тепломассообмена с газовым потоком и внутренних физико-химических процессов (теплопроводность, диффузия, фильтрация, сушка и химическая реакция). Математическая модель строится из субмоделей одиночных частиц, сопряженных по потокам теплоты и массы. Результаты численных расчетов позволяют исследовать динамическое поведение частиц в условиях плотного слоя, что представляет интерес при проектировании малых энергетических установок на биотопливе. The development of new energy technologies requires the improvement of mathematical models to describe the physical and chemical processes taking place in power plants. The process of wood particles fixed-bed pyrolysis is investigated in this paper: this process takes place both in the traditional combustion of wood fuels in fixed-bed boilers and in energotechnology processes aimed at producing combustible gases and chemical products (tar, charcoal). The problem of pyrolysis of a set of successively located wood particles is considered. Each particle is considered as an object with an internal distribution of temperature, pressure and concentrations. A system of equations is constructed for a single particle, including external heat and mass transfer between the particles and the ambient gas flow combined with internal physicochemical processes (heat conduction, diffusion, filtration, drying and chemical brutto-reaction of the organic mass decomposition producing gases and solid residue). The temperature of the gas in the pores of the particles is equal to the temperature of the solid. Using the model of pyrolysis of a single particle, it is possible to reproduce the known experimental data. The mathematical model of a fixed-bed pyrolysis is based on submodels of single particles, conjugated over heat and mass flows. The interaction between the particles composing the layer is reduced to heat fluxes: radiant heat transfer between the surfaces of adjacent particles occurs in the bed, as well as convective heat transfer between the heated gas and particles. The result is that each next particle layer is heated at a smaller temperature difference. On the one hand, the intensity of heat transfer decreases, on the other hand, the efficiency of using heat increases. The results of numerical calculations make it possible to study the dynamic behavior of particles in a fixed bed, which is of interest in the design of small power plants using biofuels.

Radiant Heat Transfer From Isothermal Dispersions With Isotropic Scattering

1967 ◽  
Vol 89 (4) ◽  
pp. 300-308 ◽  
Author(s):  
R. H. Edwards ◽  
R. P. Bobco
Keyword(s):  
Heat Transfer ◽  
Approximate Solutions ◽  
Radiant Heat ◽  
Second Order ◽  
Isotropic Scattering ◽  
Radiant Heat Transfer ◽  
Approximate Methods ◽  
First Order ◽  
Order Solution ◽  
Radiant Transfer

Two approximate methods are presented for making radiant heat-transfer computations from gray, isothermal dispersions which absorb, emit, and scatter isotropically. The integrodifferential equation of radiant transfer is solved using moment techniques to obtain a first-order solution. A second-order solution is found by iteration. The approximate solutions are compared to exact solutions found in the literature of astrophysics for the case of a plane-parallel geometry. The exact and approximate solutions are both expressed in terms of directional and hemispherical emissivities at a boundary. The comparison for a slab, which is neither optically thin nor thick (τ = 1), indicates that the second-order solution is accurate to within 10 percent for both directional and hemispherical properties. These results suggest that relatively simple techniques may be used to make design computations for more complex geometries and boundary conditions.

Heat Transfer in Chemical Vapor Deposited Optical Fiber Coatings

2001 ◽  
Author(s):  
Patricia O. Iwanik ◽  
Wilson K. S. Chiu
Keyword(s):  
Heat Transfer ◽  
Optical Fiber ◽  
Gas Flow ◽  
Convection Heat Transfer ◽  
Fiber Surface ◽  
Chemical Vapor ◽  
Temperature Changes ◽  
Flow And Heat Transfer ◽  
Chemical Vapor Deposited ◽  
Fiber Coatings

Abstract A fundamental understanding of how reactor parameters influence the fiber surface temperature is essential to manufacturing high quality optical fiber coatings by chemical vapor deposition (CVD). In an attempt to better understand this process, a finite volume model has been developed to study the gas flow and heat transfer of an optical fiber as it travels through a CVD reactor. This study showed that draw speed significantly affects fiber temperature inside the reactor, with temperature changes up to 45% observed under the conditions studied. Multiple heat transfer modes contribute to this phenomena, with convection heat transfer dominating the process.

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