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No abstract available

[en] The specific transient phenomenon under consideration is the outlet flowrate of subcooled liquid from a tube-type condenser where complete condensation takes place. Experimental data are presented which indicates that a small change in the inlet vapor flowrate will momentarily cause a very large transient surge in the outlet flowrate of subcooled liquid. These experimentally measured flow transients are predicted quite accurately using a system mean void fraction model. Also, some preliminary results are presented which indicate the influence of throttling at the condenser outlet as a means of attenuating the transient overshoot characteristics

[en] The claim of CS patent document 242057 consists in increasing the efficiency of fluoride cleaning devices and facilitating the operation of manipulators used for handling the devices in the radioactive environment. The device consists of a double-jacket vertical condenser of a cylindrical type housing a system of riser and return pipes whose top ends are coupled. The inter-jacket space and the tube insided spaces are connected to the supply and discharge of a coolant. The inter-jacket space is partitioned into an inner space whose upper part is connected to the coolant supply and the lower part to the bottom ends of the riser tubes and an outer space whose upper part is connected to the coolant discharge and its lower part to the bottom ends of the return pipes. The design also facilitates assembly and disassembly of the device which can especially be used as part of a nuclear fuel regeneration line. (Z.M.). 1 fig

[en] The method for calculation of pressure variation in a hermetic volume filled with stoking on delivery of saturated vapor is proposed. The method regards for time nonuniformity of stoking heating. Compared are the calculation and experimental data for the case of nonstationary flow of underheated and saturated water out of a pressure vessel into the 3.4 m³ hermetic volume having ceramic rings. The water regimes in the vessel at an initial temperature of 300 deg C and branch pipe diameters of 6, 10 and 15 mm are studied. It is shown that the best coincidence of the experimental curve with the calculation data (with regard for time delay, which did not affect the calculation data due to the following assumptions: the stoking heating regime is regular, vapor delivered into the drum is immediately mixed with air) is observed at different heat transfer coefficients (K). For the 6 mm diameter branch pipe the correlation is observed at K=100 W/m²xdeg C, and for the 15 mm branch pipe at K=400 W/m²xdeg C. It is explained by the fact that at greater diameters the vapour flow rate and its partial pressure increase, that leads to the increase of the heat transfer coefficient. Such magnitudes of K₂ correlate with the experimental ones

[en] The objective of this paper is to report the results of a theoretical analysis of the condensation problem inside parallel rotating heat pipe. A physical model is creatively proposed. The predictions of the theoretical expression was compared with experimental measurement

[en] In this study, the numerical analysis to estimate condensation heat and mass transfer of the condenser was carried out using the PMA (Porous Medium Approach). In the PMA, the details of tube bundle in the condenser are replaced by the porous medium, and the flow resistance term is added in the momentum equation. In this regard, the PMA is quite helpful for the study of tube bundle in the large condenser. The pressure loss through tube bundle can be compensated by viscous and inertial momentum sink terms, which was validated numerically. Value of the pressure drop was compared to that of Butterworth correlation. Three dimensional analysis of condensation for McAllister condenser with the PMA was conducted using Fluent 6.2 and UDFs (use-defined functions). The result of condensation rate was analogous to previous results (experimental and numerical data)

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[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.