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[en] Reflux and vent condensers are vertical separators where film condensation occurs. A vapour mixture is supplied at the bottom of the tubes and encounters vertical cold surfaces. A falling film forms and exits from the bottom of the tubes, flowing counter-current to the vapour, but co-current to the coolant on the shell side. Flooding occurs when the condensate flow moves from a gravity regime to a shear regime. Vapour velocities at or above the flooding velocity will cause the liquid to exit from the top of the tubes rather than from the bottom. The main disadvantage of these condensers is the limited flooding velocity allowed. Several investigators propose correlations to predict the flooding velocity. In most cases these correlations come from isothermal experiments data, thus the general recommendation of using safety factors of at least 30%. This work compares these correlations to new experimental values of flooding in steam/air vent condensation. The experimental apparatus is a 3 m long, double-pipe condenser with an internal diameter of 0.028 m. The conclusions presented here will aid the design engineer to understand better the applicability of the discussed correlations in the design of steam/air vent condensers
[en] A condensation chamber is formed between the enclosure wall and the inner wall. It is filled with a solid material capable of melting (e.g. ice) which, in case of an accident, will condense the steam entering the condensation chamber through dampers. The ice is firmly held in place by the support structure so as to be protected from earthquakes. The support structure has a large number of cylindrical vessels arranged in radial rows and subdivided into individual sections, which vessels are kept at a distance relative to each other by means of a frame. The material capable of melting can be weighed. (DG)
[de]Zwischen der Umfassungswand und der Innenwand ist eine Kondensationskammer ausgebildet. Sie ist mit schmelzbarem, festem Material (z.B. Eis) gefuellt, das bei einem Unfall den durch Klappen in die Kondensationskammer eindringenden Dampf kondensiert. Das Eis wird von der Haltekonstruktion erdbebensicher gehalten. Sie weist eine Vielzahl von in radialen Reihen angeordneten, in einzelne Abschnitte unterteilte zylindrische Behaelter auf, die gegenseitig von einem Rahmen auf Abstand gehaltert werden. Ein Wiegen des schmelzbaren Materials ist moeglich. (DG)
[en] In current paper we study the so-called “complete condensation” of zero range process on the fitness network. It is found that under the high temperature limit, the condensation behavior on the fitness model converges to that of the scale-free network, as expected. However, at some temperatures below the critical temprature of Bose–Einstein condensate phase on the fitness network, the complete condensation occurs as well for some values of δ > δ_c, which is impossible on scale-free network according to the criterion. (paper)
[en] We simulate Bose-Einstein condensation at finite temperature in a ring employing stochastic Gross-Pitaevskii equation and show that cooling through the critical point can generate topologically stable quantized circulation of the newborn condensate around the ring. The resulting winding numbers exhibiting Gaussian distribution with dispersion following scaling behavior predicted by the Kibble-Zurek mechanism (KZM). This opens up possibilities for direct experimental study of the underlying phase transition and the basic principles of KZM extended to account for such circulations. We discuss the effect of inhomogeneity on the above phenomenon by considering the effect of tilting of the ring in the gravitational field.
[en] The results of experimental investigation of heat exchange at the condensation of water vapor from vapor-air mixtures are presented. The experimental investigations are carried out on the models of surface and bubbling-type condensers. The results obtained are shown in the form generalizing relations. Devised methods can be recommended for calculation surface and bubbling-type condensers. (Author)
[en] The thermal design of an industrial shell-and-tube condenser requires the use of heat transfer coefficients, usually obtained from tables or correlations. Willing to develop a numerical model for design purposes, the present authors noticed the surprising diversity of correlations for the shellside heat transfer coefficient in the case of pure vapour condensation outside of horizontal smooth tubes. In order to shed light on this specific topic, a bibliographic study was therefore initiated. This comprehensive review is meant to provide the designers with means to understand how each correlation was obtained, from the assumptions to the resolution method. Thus two main phenomena are well accounted for in this paper: vapour shear stress and condensate inundation. Indeed, the review lists the most important contributions to this field and details their interconnections. Consequently, the present authors conclude this paper with their recommendations.
[en] In this work, inelastic light-scattering (Bragg spectroscopy) is used to study strongly correlated phases of ultracold 1D gases in optical lattices. We investigate the crossover from correlated superfluids to Mott insulators. Light-scattering creates in the system elementary excitations with non-zero momentum, and the response of the correlated gases is in the linear regime. This allows for extracting information about the atomic many-body state in terms of its particle-hole excitations, as common in solid-state physics. In particular, we characterize the Mott state both via intra-band and inter-band spectroscopy, the former giving access to the dynamical structure factor S(q,ω) and the latter to the one-particle spectral function Α(q,ω).