Wyniki wyszukiwania - BazTech

1

Modelling heat flow in a heat storage system with the use of the Finite Volume Method

Sobieski Wojciech

Journal of Applied Computer Science

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2019

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Vol. 27, nr 1

27--49

EN

Non-stationary heat flow was analysed in a heat storage system comprising a flat multilayer structure with different parameters and thickness. Concrete was the heat storage material, and water was the transfer medium responsible for supplying and evacuating heat from the storage medium. It was assumed that the modelled heat storage system may be powered by a solar thermal collector. Data were collected over a period of 24 hours, and they were analysed separately for the heat accumulation phase and the heat recovery phase. Calculations were performed in a program developed by the author based on the Finite Volume Method (FVM). The main aim is to illustrate the basic features of the developed numerical code and to find effective methods for evaluating the applicability of the modelled structures for heat storage. Except that, in the paper the possibilities are discussed for the use of the source component of the diffusion equation to describe various phenomena of physical, chemical and biological nature. The present article was motivated by the observation that FVM is currently not applied in the process of designing heat storage systems.

2

Numerical study of natural convection in a vertical cylindrical partially annular

Medebber M. A., Retiel N.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 1

77--92

EN

A study of free convection in a vertical cylinder partially annulus is conducted numerically. Uniform temperature is imposed cross a vertical wall, while the top and bottom walls are adiabatic. The governing equations are solved numerically by using a finite volume method. The coupling between the continuity and momentum equations is effected using the SIMPLER algorithm. Solutions have been obtained for Prandtl numbers equal to 7.0, Rayleigh numbers of 103 to 106 and height ratios of 0 to 1. The influence of physical and geometrical parameters on the streamlines, isotherms, average Nusselt has been numerically investigated.

3

Discretisation of thermal diffusion equation in multilayer structures with variable material parameters and different thicknesses

Sobieski W., Trykozko A.

Journal of Applied Computer Science

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2018

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Vol. 26, nr 2

213--240

EN

The paper presents details of discretisation of a thermal diffusion equation in one-dimensional space in terms of the Finite Volume Method. In the following sections, the method of space discretisation is discussed along with the approximation of a spatial derivative, matrix notation of a system of equations, special cases, approximation of three types of boundary conditions and derivative approximation over time. Much attention is also given to the issue of averaging material properties which can generally be different in adjacent cells.The study aims to analyse various multilayer structures for their suitability as heat storage. The launch of studies described in the paper has been driven by the lack of methods for effective heat storage, which is currently one of the key problems faced by the renewable energy industry.

4

Coupled finite volume and finite element method analysis of a complex large-span roof structure

Szafran J., Juszczyk K., Kamiński M.

International Journal of Applied Mechanics and Engineering

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2017

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Vol. 22, no. 4

995--1017

EN

The main goal of this paper is to present coupled Computational Fluid Dynamics and structural analysis for the precise determination of wind impact on internal forces and deformations of structural elements of a longspan roof structure. The Finite Volume Method (FVM) serves for a solution of the fluid flow problem to model the air flow around the structure, whose results are applied in turn as the boundary tractions in the Finite Element Method problem structural solution for the linear elastostatics with small deformations. The first part is carried out with the use of ANSYS 15.0 computer system, whereas the FEM system Robot supports stress analysis in particular roof members. A comparison of the wind pressure distribution throughout the roof surface shows some differences with respect to that available in the engineering designing codes like Eurocode, which deserves separate further numerical studies. Coupling of these two separate numerical techniques appears to be promising in view of future computational models of stochastic nature in large scale structural systems due to the stochastic perturbation method.

5

Numerical simulations of epitaxial growth in MOVPE reactor as a tool for aluminum nitride growth optimization

Skibinski J, Caban P., Wejrzanowski T., Grybczuk M., Kurzydlowski K. J.

Journal of Power Technologies

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2016

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Vol. 96, nr 2

110--114

EN

The present study concerns numerical simulations and experimental measurements on the influence of inlet gas mass flow rate on the growth rate of aluminum nitride crystals in Metalorganic Vapor Phase Epitaxy reactor model AIX-200/4RF-S. The aim of this study was to design the optimal process conditions for obtaining the most homogeneous product. Since there are many agents influencing reactions relating to crystal growth such as temperature, pressure, gas composition and reactor geometry, it is difficult to design an optimal process. Variations of process pressure and hydrogen mass flow rates have been considered. Since it is impossible to experimentally determine the exact distribution of heat and mass transfer inside the reactor during crystal growth, detailed 3D modeling has been used to gain insight into the process conditions. Numerical simulations increase the understanding of the epitaxial process by calculating heat and mass transfer distribution during the growth of aluminum nitride crystals. Including chemical reactions in the numerical model enables the growth rate of the substrate to be calculated. The present approach has been applied to optimize homogeneity of AlN film thickness and its growth rate.

6

Influence of hydrogen volumetric flow rate on temperature distribution in CVD reactor based on epi-growth of SiC

Skibinski J., Wejrzanowski T., Teklinska D., Kurzydlowski K. J.

Journal of Power Technologies

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2015

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Vol. 95, nr 2

119--125

EN

In the present paper the quantitative relationship between the heat and mass transfer in the Aixtron VP508 hot wall CVD reactor and the epitaxial growth of silicon carbide is determined. The aim of this study was to estimate optimal process conditions for obtaining monocrystalline silicon carbide epi-layers with the most homogenous thickness. Since there are many parameters influencing reactions on the crystal area, such as temperature, pressure, gas flow and reactor geometry, it is difficult to design an optimal process. Detailed 3D modeling was used to gain insight into the process conditions, as it is problematic to experimentally determine the exact distribution of heat and mass transfer inside the reactor during epitaxial growth. Numerical simulations allow one to understand the process by calculating the heat and mass transfer distribution during the epitaxial growth of silicon carbide. The present approach was applied to enhance the performance of the Aixtron VP508 reactor.