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The measurement of the heterogeneous particles in the steam
Bartoš, Ondřej ; Hrubý, Jan ; Ždímal, Vladimír ; Kolovratník, Michal ; Jiříček, I. ; Moravec, Pavel ; Zíková, Naděžda
The aim of this extended abstract is to reveal the work done as cooperation between several institutions which was presented and published in recent years (Kolovratník, 2014). The formation of droplets in low-pressure steam turbines has a significant impact on the efficiency of energy conversion due to the strongly nonequilibrium nature of this process . The condensed water also erodes the turbine blades. A very important question is to what extent heterogeneous nucleation contributes to the phase transition process . In the case of heterogeneous nucleation , the number of droplets depends only on the number of h eterogeneous particles in the system, whereas in the case of homogeneous nucleation, the number of created droplets is determined rather by the expansion rate - in a faster expansion, greater supersaturation and more droplets are formed until the released condensation enthalpy quenches the nucleation.\nThe specific number of droplets (number of droplets per unit mass of steam) formed in the turbine can be determined by optical probes, developed first by Walters and later in the Czech Republic improved by Petr and Kolovratník. Until recently, no information was available on the relative importance of heterogeneous nucleation in forming these droplets.
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Modelling of Binary Nucleation in Laminar Co - Flow Tube.
Trávníčková, Tereza ; Havlica, Jaromír ; Hrubý, Jan ; Ždímal, Vladimír
Particle nucleation is one of the important phenomena encountered in both chemical engineering and environmental studies. The Laminar Co-Flow Tube (LCFT) was designed for experimental measurement of binary and ternary nucleation of mixtures of atmospheric aerosols at laboratory conditions, most often H2SO4 + H2O + amines (MEA, TEA)/terpenes (alfa-pinene, limonene). Two models were used for mathematical modeling of momentum and mass transfer in the LFDC. 2D axisymmetric CFD model and simplified 1D analytical model. A parametric study was carried out using both models and the influence of the individual simplifications of analytical model on overall behavior of the system was discussed.
Plný tet: SKMBT_C22019110512052 -  PDF
Plný text: content.csg - PDF
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