Numerical Analysis of Crust Behavior of Molten Core and Concrete Interaction by Using MPS Method

2014 ◽  
Author(s):  
Takeo Watanabe ◽  
Yoshiaki Oka
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Particle Interaction ◽  
Nucleate Boiling ◽  
Phase Changes ◽  
Solid Particles ◽  
Experimental Result ◽  
Conductive Heat ◽  
Radiation Heat ◽  
Mps Method

Moving particle semi-implicit (MPS) method is the particle (girdles) method for incompressible medium. Particles are used for discretization of fluids, and governing equations are transformed to particle interaction models. Phase changes are treated as changing particle dynamics. The interface is treated accurately. In the present study, two-dimensional code is created for molten core concrete interaction (MCCI) by using MPS method. Each particle has enthalpy, and three types of heat transfer are treated. Conductive heat transfer is calculated with Laplacian model of MPS. Nucleate boiling and radiation heat transfer is calculated by removing enthalpy from surface particles. Liquid particles can be changed to solid particles depending on their enthalpy. These particles are fixed to space. Semi-implicit method is used in original MPS method, but in this study, explicit method is introduced in order to increase calculation speed. The SWISS-1 and SWISS-2 experiments are analyzed. Gas release from concrete is ignored, and melting of concrete is treated as disappearing of particles. This generate void between crust bridge and liquid debris in SWISS-2, and crust bridge is heated mainly by radiation heat transfer. Calculated ablation rate of concrete agrees well with experimental results of SWISS-1 and SWISS-2, but calculated heat flux from crust bridge to the water pool of SWISS-2 is lower. It is because the water penetration through the crust is ignored, and the amount of penetrated water is estimated by the difference between calculation and experimental result.

scholarly journals An algorithm for solving the boundary value problem of radiation heat transfer without boundary conditions for radiation intensity

2020 ◽  
pp. 114-122
Author(s):  
A.Yu. Chebotarev ◽  
◽  
P.R. Mesenev ◽  
Keyword(s):  
Heat Transfer ◽  
Boundary Value Problem ◽  
Boundary Conditions ◽  
Radiation Intensity ◽  
Radiation Transfer ◽  
Boundary Value ◽  
Radiation Heat Transfer ◽  
Three Dimensional ◽  
Conductive Heat ◽  
Radiation Heat

An optimization algorithm for solving the boundary value problem for the stationary equations of radiation-conductive heat transfer in the three-dimensional region is presented in the framework of the $ P_1 $ - approximation of the radiation transfer equation. The analysis of the optimal control problem that approximates the boundary value problem where they are not defined boundary conditions for radiation intensity. Theoretical analysis is illustrated by numerical examples.

scholarly journals Radiation Heat Transfer in a Complex Geometry Containing Anisotropically-Scattering Mie Particles

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3986 ◽  
Author(s):  
Ali Ettaleb ◽  
Mohamed Abbassi ◽  
Habib Farhat ◽  
Kamel Guedri ◽  
Ahmed Omri ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Fly Ash ◽  
Complex Geometry ◽  
Radiation Heat Transfer ◽  
Solid Particles ◽  
Isotropic Scattering ◽  
Isotropic Case ◽  
Radiation Heat ◽  
Radiation Heat Flux

This study aims to numerically investigate the radiation heat transfer in a complex, 3-D biomass pyrolysis reactor which is consisted of two pyrolysis chambers and a heat recuperator. The medium assumes to be gray, absorbs, emits, and Mie-anisotropically scatters the radiation energy. The finite volume method (FVM) is applied to solve the radiation transfer equation (RTE) using the step scheme. To treat the complex geometry, the blocked-off-region procedure is employed. Mie equations (ME) are applied to evaluate the scattering phase function and analyze the angular distribution of the anisotropically scattered radiation by particles. In this study, three different states are considered to test the anisotropic scattering impacts on the temperature and radiation heat flux distribution. These states are as: (i) Isotropic scattering, (ii) forward and backward scattering and (iii) scattering with solid particles of different coals and fly ash. The outcomes demonstrate that the radiation heat flux enhances by an increment of the albedo and absorption coefficients for the coals and fly ash, unlike the isotropic case and the forward and backward scattering functions. Moreover, the particle size parameter does not have an important influence on the radiation heat flux, when the medium is thin optical. Its effect is more noticeable for higher extinction coefficients.

Gas-Particle Flow Within a High Temperature Solar Cavity Receiver Including Radiation Heat Transfer

1987 ◽  
Vol 109 (2) ◽  
pp. 134-142 ◽  
Author(s):  
G. Evans ◽  
W. Houf ◽  
R. Greif ◽  
C. Crowe
Keyword(s):  
Heat Transfer ◽  
Radiation Heat Transfer ◽  
Particle Interaction ◽  
Computer Code ◽  
Solid Particles ◽  
Forced Flow ◽  
Discrete Ordinates ◽  
Temperature Profiles ◽  
Thermal Coupling ◽  
Solar Receiver

A study has been made of the flow of air and particles and the heat transfer inside a solar heated, open cavity containing a falling cloud of 100-1000 micron solid particles. Two-way momentum and thermal coupling between the particles and the air are included in the analysis along with the effects of radiative transport within the particle cloud, among the cavity surfaces, and between the cloud and the surfaces. The flow field is assumed to be two-dimensional with steady mean quantities. The PSI-Cell (particle source in cell) computer code is used to describe the gas-particle interaction. The method of discrete ordinates is used to obtain the radiative transfer within the cloud. The results include the velocity and temperature profiles of the particles and the air. In addition, the thermal performance of the solid particle solar receiver has been determined as a function of particle size, mass flow rate, and infrared scattering albedo. A forced flow, applied across the cavity aperture, has also been investigated as a means of decreasing convective heat loss from the cavity.

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