Janusz Wójcik

Two-phase CFD simulation of the monodyspersed suspension hydraulic behaviour in the tank apparatus from a circulatory pipe

Two-phase CFD simulation of the monodyspersed suspension hydraulic behaviour in the tank apparatus from a circulatory pipe The hydrodynamics in fluidized-bed crystallizers is studied by CFD method. The simulations were performed by a commercial packet of computational fluid dynamics Fluent 6.x. For the one-phase modelling (15), a standard k-ε model was applied. In the case of the two-phase flows the Eulerian multi-phase model with a standard k-ε method, aided by the k-ε dispersed model for viscosity, has been used respectively. The collected data put a new light on the suspension flow behaviour in the annular zone of the fluidised bed crystallizer. From the presented here CFD simulations, it clearly issues that the real hydraulic conditions in the fluidised bed crystallizers are far from the ideal ones.

CPU Heat Sink Cooled by Nanofluids and Water: Experimental and Numerical Study

Abstract In this study, a commercial heat sink was employed for cooling a PC processor. Two liquids were used (i) water and (ii) copper oxide (II) nanofluids with 0.0086 and 0.0225 volume fractions. In the experiments, the heat sink was fixed to the CPU. The maximal power dissipated by the investigated processor was 115 W. The mass flow rate of the liquids was in the range of 0.009 to 0.05 kg/s and the inlet temperature was in the range of 300 to 305 K. The experimental results were used to validate the numerical model of the analyzed system. The commercial package ANSYS Fluent 13 was employed to generate a CFD heat transfer simulation. A laminar flow regime was proposed in a fin array area of the heat sink. An appropriate grid quality model was developed and validated. The obtained results showed that water was sufficient enough for CPU cooling.

Multiphase CFD modeling - scale-up of Fluidized-Bed Crystallizer

Abstract The main goal of this study was to obtain a closer look to scale up problem of the Fluidized-Bed crystallizer operation, in particular for solids concentration larger than 10 vol.%. To achieve that a multi-phase CFD code was used. Such an approach to this problem has not been investigated until now. Data collected using CFD technique, impossible to obtain in any other way, especially for an industrial apparatus, provides the information about the suspension flow behaviour in such crystallizers.

Distribution of Traces During Precipitation of Barium Carbonate

Abstract In this article, we investigate the distribution of traces of Na, K, Ca, and Sr during the fractionated precipitation of barium carbonate from barium chloride solution with ammonium carbonate. The results of trace distributions were determined with 24Na, 42K, 45Ca, and 85Sr isotopes. In a concentration range of 1 × 10−4 to 1 × 10−3 % (related to BaCl2) at 80% of matrix precipitation the following quantities of trace impurities remained in the solution (%) Na: 89–94, K: 92–98, Ca: 38–47, and Sr: 35–26. The influence of DCTA complexing agent on impurities distribution was found to be insignificant. The distribution of Cd(II), Co(II), Cu(II), Fe(III), Mn(II), Ni(II), Pb(II), and Zn(II) in single‐mode precipitation BaCO3 with (NH4)2CO3 was also investigated in the presence of EDTA and DCTA, and without any complexing agent. The AAS method was used to determine traces of heavy metal content. After a precipitation of 80% of matrix BaCO3 in presence EDTA, and 1 × 10−4 % initial trace concentrations, the following quantities (%) of 55 Cd, 70 Co, 72 Cu, 52 Fe, 70 Mn, 83 Ni, 60 Pb, and 67 Zn remained in the solution. The results were used for the optimization of BaCO3 obtainment.