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Measurement of heat transfer on an experimental exchanger with a specially-shaped capillary tube
Peukert, Pavel ; Hrubý, Jan
First results were evaluated from tests with a new experimental condensation heat exchanger with a corrugated capillary tube. Several measurements were performed at different inlett steam pressure levels (from 2.3 to 7.4 bar) and different flow velocities on the cooling side of the tube. One of the goals is to observe the effective length of the corrugated tube. The second objective is determining the dependence on the flow velocity of the cooling water. Klíčová slova: condensation heat exchanger, minichanel tube heat
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Nonequilibrium condensation processes in steam turbines in the light of new measurements of heterogeneous particles
Hrubý, Jan ; Kolovratník, M. ; Ždímal, Vladimír ; Bartoš, Ondřej ; Moravec, Pavel ; Jiříček, I.
In a steam turbine, droplets are formed either homogeneously or via heterogeneous nucleation on pre-existing heterogeneous particles. In a pioneering work, the present team developed a system to measure the number and size of heterogeneous particles down to diameter of 3 nm. This work reports on measurements at Power Plant Prunéřov II. For the first time, the data is at higher parameters (0.27 MPa, 250°C), and the diffusion battery was used to determine the size distribuition of the particles, showing count-mean diameter of about 13 nm.
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Numerical simulation of external and internal transonic flows
Huml, J. ; Kozel, K. ; Příhoda, Jaromír
This work deals with the numerical solution of transonic flows of an inviscid compressible fluid in a two- and three-dimensional channel and in a two-dimensional DCA 8% cascade. The numerical solution was obtained by the finite volume method using the multistage Runge-Kutta method and Lax-Wendroff scheme on structured non-orthogonal grids. Jameson's artificial dissipation was added to increase of the numerical stability.
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Computation of inviscid and viscous turbulent subsonic and transonic flows
Trefilík, J. ; Kozel, K. ; Příhoda, Jaromír
The work deals with the developement of numerical methods for simulation of subsonic and transonic turbulent flows in the GAMM channel and through the DCA 8% cascade. Results of numerical modelling of viscous and inviscid flows with the inlet Mach numbers M = 0.6, 0.675 and 0.85 are compared and discussed. For turbulence modelling one equation algebraic Baldwin-Lomax model and two equations k-omega model were applied and their numerical results were compared.
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Experimental and numerical modelling of liquid flow with separation
Zubík, P. ; Šulc, J. ; Příhoda, Jaromír ; Sedlář, M.
The contribution deals with the experimental and numerical modelling of turbulent pressure, subcritical and supercritical flow with massive separation due to sudden expansion of the cross section (flow over an inclined step). Experiments were carried out in the water channel with the cross-section 200x200 mm by means of PIV and LDA measuring methods. Numerical simulation was carried out using the VOF (Volume-of-Fluid) method by means of the commercial software ANSYS CFX-12.0. Numerical results were compared with experimental data.
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