Phase steam—water

This book proposes that in two-phase steam-water systems, there axe. four fundamental waterside problem areas ... 

Isbin, H. S., Vanderwater, R., Fauske, H., and Singh, S., A model for correlating two phase, steam water, burnout heat transfer fluxes, J. Heat Transfer 83, 149 (1961). 

The behavior of the flow pattern in a parallel micro-channel is different from that in a single micro-channel. It was shown by Hetsroni et al. (2003b) that at the same value of heat flux, different flow regimes may be observed in different micro-channels, depending on the time interval. Moreover, at the same time interval different flow regimes may exist in each of the component micro-channels. In Fig. 2.33 two-phase steam-water flow in the central part of such a parallel system db = 100 pm is shown as the top view observed through a transparent cover. The... 

Hosier, E. R., 1968, Flow Patterns in High Pressure Two-Phase (Steam-Water) Flow with Heat Addition, AIChE Chem. Eng. Prog. Symp. Ser. <54(82) 54, AIChE, New York. (3)... 

Isbin, H. S., R. Vanderwater, H. K. Fauske, and S. Singher, 1961, A Model for Correlating Two-Phase, Steam-Water, Burnout Heat Transfer Fluxes, Trans. ASME, J. Heat Transfer 83 149-157. (5) Ishii, M., 1975, Thermo Fluid Dynamic Theory of Two-Phase Flav, chaps. IX and X, Eyralles Press, Paris (Sci. and Medical Pub. of France, New York). (3)... 

JAEA conducted an improvement of the RELAP5 MOD3 code (US NRC, 1995), the system analysis code originally developed for LWR systems, to extend its applicability to VHTR systems (Takamatsu, 2004). Also, a chemistry model for the IS process was incorporated into the code to evaluate the dynamic characteristics of process heat exchangers in the IS process (Sato, 2007). The code covers reactor power behaviour, thermal-hydraulics of helium gases, thermal-hydraulics of the two-phase steam-water mixture, chemical reactions in the process heat exchangers and control system characteristics. Field equations consist of mass continuity, momentum conservation and energy conservation with a two-fluid model and reactor power is calculated by point reactor kinetics equations. The code was validated by the experimental data obtained by the HTTR operations and mock-up test facility (Takamatsu, 2004 Ohashi, 2006). 

The overall transfer coefficients (related to the overall transfer area) obtained in this three-phase two-component condensation study were about 600 and 1100 Btu/hr/ft /°F for the large and small bubbles, respectively. These compare favorably with the values reported for condensation of steam in water, which are, however, one order of magnitude larger. The difference is reasonable in view of the possibility for mass diffusion at the gas-liquid interface in the two-phase steam-water system, as well as the much higher turbulence encountered, especially in Bankoff s system (B2). 

The MHT system transports heat from the fuel rods to the light-water coolant. The two-phase steam-water mixture produced in the reactor core, enters the steam dryer through the steam separator at the upper plenum, see Fig. IX-2. Steam separated from the steam-water mixture in the steam separator and dryer enters the steam dome. Two pipes collect steam from the steam dome and transfer it to the steam chest of the turbine. 

Concerned about the raising water in the pressurizer, about 2 min after accident mitigation began, the control room opoators turned off one of the HPI pumps and throttled the outlet to the second. These actions reduced the makeup flow to the RCS to about 100 gpm (Rogovin and Frampton, 1980). Despite the continuing decrease in RCS pressure due to the constant loss of fluid from the stuck open PORV, the operators were determined to maintain a two phase steam/water mixture inside the pressurizer. 

For the steam plant, the condenser pressure, the turbine and pump efficiencies are also specified there is also a single phase of water/steam heating, with no reheating. The feed pump work term for the relatively low pressure steam cycle is ignored, so that /ij, = /i. For the HRSG two temperature differences are prescribed ... 

Various amines find application for pH control. The most commonly used are ammonia, morpholine, cyclohexylamine, and, more recently AMP (2-amino-2-methyl-l-propanol). The amount of each needed to produce a given pH depends upon the basicity constant, and values of this are given in Table 17.4. The volatility also influences their utility and their selection for any particular application. Like other substances, amines tend towards equilibrium concentrations in each phase of the steam/water mixture, the equilibrium being temperature dependent. Values of the distribution coefficient, Kp, are also given in Table 17.4. These factors need to be taken into account when estimating the pH attainable at any given point in a circuit so as to provide appropriate protection for each location. 

Foam formation in a boiler is primarily a surface active phenomena, whereby a discontinuous gaseous phase of steam, carbon dioxide, and other gas bubbles is dispersed in a continuous liquid phase of BW. Because the largest component of the foam is usually gas, the bubbles generally are separated only by a thin, liquid film composed of several layers of molecules that can slide over each other to provide considerable elasticity. Foaming occurs when these bubbles arrive at a steam-water interface at a rate faster than that at which they can collapse or decay into steam vapor. 

This chapter is restricted to homogeneous, single-phase reactions, but the restriction can sometimes be relaxed. The formation of a second phase as a consequence of an irreversible reaction will not affect the kinetics, except for a possible density change. If the second phase is solid or liquid, the density change will be moderate. If the new phase is a gas, its formation can have a major effect. Specialized models are needed. Two-phase ffows of air-water and steam-water have been extensively studied, but few data are available for chemically reactive systems. 

Green, J. C. and Donaldson, R. M., The role played by ion chromatography in the assessment of amines for two-phase erosion corrosion control in nuclear electric s steam-water circuits, ]. Chromatogr., 640, 303, 1993. 

Murdock (1962) has tested the two-phase flows of steam-water, air-water, natural gas-water, natural gas-salt water, and natural gas-distillate combinations in 2.5-, 3-, and 4-in. pipes with orifice-to-pipe diameter ratios ranging from 0.25 to... 

Bankoff, S. G., 1960, A Variable-Density, Single-Fluid Model for Two-Phase Flow with Particular Reference to Steam-Water Flow, Trans. ASME, J. Heat Transfer 52 265-272. (3)... 

Collier, J. G., and D. J. Pulling, 1962, Heat Transfer to Two-Phase Gas-Liquid System, Part II, Further Data on Steam-Water Mixtures in the Liquid Dispersed Region in an Annulus, UK Rep. AERE-R-3809, Harwell, England. (4)... 

Janssen, E., 1967, Two Phase Flow Structure in a Nine-Rod Channel, Steam-Water at 1000 psia, Final Summary Rep. GEAP-5480, General Electric, San Jose, CA. (5)... 

Kumamaru, H., Y. Koizumi, and K. Tasake, 1987, Investigation of Pre- and Post-Dryout Heat Transfer of Steam-Water Two-Phase Flow in Rod Bundles, Nuclear Eng. Design 702 71-84. (4) Kutateladze, S. S., 1952, Heat Transfer in Condensation and Boiling, USAEC Rep. AEC-tr-3770 (Translated from Mashgiz, 2d ed., pp. 76-107, State Sci. Tech. Pub. House of Literature on Machinery, Moscow-Leningrad). (2)... 

Nakamura, H., Y. Anoda, and Y. Kukita, 1991, Flow Regime Transition in High Pressure Steam-Water Horizontal Pipe Two-Phase Flow, Proc. ANS Natl. Heat Transfer Conf, Minneapolis, MN, p. 269. (3)... 

Re ocreux, M., 1977, Experimental Study of Steam-Water Choked Flow, Proc. Transient Two-Phase Flow Specialists Meeting, CSNI, Aug. 1976 Atomic Energy of Canada 2 637-669. (3)... 

Ice is a solid form of water, and is its only stable form below 0 °C. The liquid form of H20 is the only stable form in the temperature range 0 < T < 100 °C. Above 100 °C, the normal, stable phase is gaseous water, steam . Water s normal melting temperature 7(meit) is 0°C (273.15 K). The word normal in this context implies at standard pressure p . The pressure has a value of 105 Pa. This temperature T tneiu is often called the melting point because water and ice coexist indefinitely at this temperature and pressure, but at no other temperature can they coexist. We say they reside together at equilibrium. 

The review of Martynova (18) covers solubilities of a variety of salts and oxides up to 10 kbar and 700 C and also available steam-water distribution coefficients. That of Lietzke (19) reviews measurements of standard electrode potentials and ionic activity coefficients using Harned cells up to 175-200 C. The review of Mesmer, Sweeton, Hitch and Baes (20) covers a range of protolytic dissociation reactions up to 300°C at SVP. Apart from the work on Fe304 solubility by Sweeton and Baes (23), the only references to hydrolysis and complexing reactions by transition metals above 100 C were to aluminium hydrolysis (20) and nickel hydrolysis (24) both to 150 C. Nikolaeva (24) was one of several at the conference who discussed the problems arising when hydrolysis and complexing occur simultaneously. There appear to be no experimental studies of solution phase redox equilibria above 100°C. 

The release of radioactive iodines from BWR circuits, first into the steam phase and then into the turbine hall, has also been considered thermodynamically (75). A re-analysis of some experimental data of Styrikovich et al (97), suggested that iodates were not, as had been tentatively proposed, likely to be present. Styrikovich s prediction of HIO as a principal species under BWR conditions was confirmed, but it was concluded that his experiments had not measured its steam/water partition coefficient. In view of the meagre experimental evidence, however, more work on this system is desirable. 

Three major reviews exist which give detailed coverage of the literature available up to about 1955. In particular, the review by Gresham et al. (G7) may be consulted for empirical correlations limited to specific flow patterns, and the papers by Isbin et al. (II) and by Bennett (B9) are particularly valuable for aspects of two-phase flow related to steam-water systems. Bennett has also given useful tabulations of available correlations (up to 1957) for the estimation of two-phase pressure drops. 

Foster Wheeler Development Corporation (FWDC) has designed a transportable transpiring wall supercritical water oxidation (SCWO) reactor to treat hazardous wastes. As water is subjected to temperatures and pressures above its critical point (374.2°C, 22.1 MPa), it exhibits properties that differ from both liquid water and steam. At the critical point, the liquid and vapor phases of water have the same density. When the critical point is exceeded, hydrogen bonding between water molecules is essentially stopped. Some organic compounds that are normally insoluble in liquid water become completely soluble (miscible in all proportions) in supercritical water. Some water-soluble inorganic compounds, such as salts, become insoluble in supercritical water. 

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