Modelling and computer simulation of reagents diffusion in high temperature diffusion controlled heterogeneous reactions
Purpose: In this paper a computational method which takes into account convection in the melting metal and slag phases is discussed. Design/methodology/approach: A deterministic computational model of high-temperature heterogeneous reaction between metal and oxide melts has been developed. Findings: Transport of reagents and products of reaction occur simultaneously both by diffusion and by laminar natural convection of the melting metal and oxide fluxes. The convection-diffusion equations have been numerically solved by a finite-differences time-implicit discretization scheme. The model was implemented by program which had been written in C# language. The computations have been performed for desulfurization reaction between liquid metal and slag phases. Research limitations/implications: To verify the reliability of the model, the computed results have been compared with experimental data. The good agreement has been obtained. The numerical results agree well with the results which were found by two independent experiments. Originality/value: This computational model enables to obtain results, for example sulfur concentration changes along the x axis, which is very difficult, almost impossible, to get by experiment. Using this mathematical model allows to predict the distribution of elements in the metal during the refining process and to reduce expenses in selection of optimum process’ conditions, which provide the metal with required composition. This model can be used for quantitative analysis of the diffusion stage of the heterogeneous reactions.
A Sulfur Diffusion Investigation in Metal and Oxide Phases
The purpose of the present work is to investigate the mutual interaction between the melted metal and oxide phases with a small amount of sulfur. In this research, the following phases took part: metallic phase of Fe – C – S and slag CaO–Al2O3 –MgO–S. The mathematical model of sulfur diffusion in the metal and oxide is employed. The experiment was carried out at the temperature of 1773K. The result of the calculation is in qualitative agreement with the experiment. The proposed approach can be applied to the investigations of diffusion processes in molten metal and slag phases.
17 &mgr;m pixel 640 x 480 microbolometer FPA development at BAE Systems
BAE Systems has developed an advanced 640 x 480 focal plane array (FPA) with a 17 &mgr;m pixel pitch. Sensitivity of ≤ 50 mK was demonstrated and the FPAs were used in imaging demonstrations. Successful scaling of BAE Systems' patented single contact per pixel, single-level microbolometer process to 17 &mgr;m pitch provides a path toward next generation microbolometer imaging systems.