Subcooled Liquid Water

A thermally insulated (adiabatic) constant-volume bomb has been very carefully prepared so that half its volume, is filled with water vapor and half with subcooled liquid water, both at — 10°C and 0.2876 kPa (the saturation pressure of the subcooled liquid). Find the temperature, pressure, and fraction of water in each phase after equilibrium has been established in... 

If you are very careful to use very pure water, and to exclude all crystallization nuclei, it is possible to subcool liquid water to temperatures far below its equilibrium freezing point (see Figure 5.8). a. Estimate the vapor pressure of subcooled liquid water at — 10°C, using the Clausius-Clapeyron equation, starting at the triple poinL at which point... 

In the previous problem you compared the vapor pressure of ice at — 10°C (=14°F) to that of subcooled liquid water at the same temperature. Using values from that problem, your thermodynamics textbook, or any other source you like, estimate by how much subcooled liquid water at — 10°C wiU increase or decrease its Gibbs energy when it changes to ice at the same temperature. 

From Table I, the specific volume of saturated water vapor with respect to ice at 5 F is 11 550 fl /lb from which IF , jp = 0.000 086 6, but the observed water dew point was in equilibrium with subcooled liquid water at 5 F. From Table I (data from International Critical Tables ), the vapor pressures of subcooled liquid water and of ice at 5 F (-15 C) are 1.436 mm and 1.241 mm Hg, respectively. 

Since the vapor pressure of subcooled liquid water is greater than ice at the same temperature, the weight per cubic foot of water vapor in equilibrium with liquid water will be proportionately larger than the value calculated from the specific volume read from the table, which is for equilibrium with ice. 

Property values for superheated water vapor and subcooled liquid water are presented in Appendices B.4 and B.5, respectively. In these regions, T and P are independent, so if we specify both, we constrain the state of the system. The tables are organized first according to pressure, then by temperature at each specified pressure. With T and P specified, values of the other properties (o, m, h, and s) are reported. The data in the superheated steam tables begin with the saturated state, whereas the data in the subcooled water tables end at saturation. The usefulness of the steam tables is that in knowing any two independent properties of water, we may look up the values of any of the other properties to solve engineering problems. 

Determine the mass of 1 L of saturated liquid water at 25°C. How do you think this value compares to the mass of IL of subcooled liquid water at 25°C and atmospheric pressure ... 

The diagram in Fig. 11-101 presents enthalpy data for LiBr-water solutions. It is needed for the thermal calculation of the cycle. Enthalpies for water and water vapor can be determined from the table or properties of water. The data in Fig. 11-101 are apphcable to saturated or subcooled solutions and are based on a zero enthalpy of liquid water at 0°C and a zero enthalpy of solid LiBr at 25°C. Since... 

Fhix-force-condensation scrubbers combine the effects of flux force (diffiisiophoresis and thermophoresis) and water-vapor condensation. These scrubbers contact hot, humid gas with subcooled liquid, and/or they inject steam into saturated gas, and they have demonstrated that a number of these novel devices can remove fine particulates (see Fig. 25-24). Although limited in terms of commercialization, these systems may find application in many industries. 

TABLE 10.6 Vapor Pressures, Subcooled Liquid Vapor Pressures (pL), Solubilities in Water (S, Cs),... 

Steam trap Used to drain water from a steam system, stuttering feed interruption Erratic flow of liquid into a heater, subcooled Liquid below its boiling point. 

Physicochemical properties are necessary for describing chemical fate, transport, and bio accumulation. The most useful of these are the subcooled liquid vapor pressure (p (, Pa), water solubility ( ig f 1), and the octanol-water (Ko r), octanol-air (Koa) and air-water (Kaw) partition coefficients. The available measured data on these properties for PCN congeners are summarized in Table 3. 

Subcooled liquid flashing/no vapour at the inlet and no non-condensable gas This scenario can be applied to hot water and covers, therefore, the ASME VIII Appendix M, Figure 11-2. 

The conditions of steam generation in the boiler are the same as in Example 8.1 8,600 kPa and 500°C. The exhaust pressure of the turbine, lOkPa, is also the same. The saturation temperature of the exhaust steam is therefore 45.83°C. Allowing for slight subcooling of the condensate, we fix the temperature of the liquid water from the condenser at 45°C. The feedwater pump, which operates under exactly the conditions of the pump in Example 7.10, causes a temperature rise of about 1°C, making the temperature of the feedwater entering the series of heaters equal to 46°C. 

Pure water may coexist as liquid and vapor only at temperature-pressure pairs that fall on the vapor-liquid equilibrium (VLE) curve. At points above the VLE curve (but to the right of the solid-liquid equilibrium curve), water is a subcooled liquid. At points on the VLE curve, water may be saturated liquid or saturated steam (vapor) or a mixture of both. At points below the VLE curve, water is superheated steam. 

Figure 4 Comparison of numerical simulations with experimental data (a) Effect of wall superheat, (b) elfect of liquid subcooling (fluid water, (fc = 54 , g = l.Oge).

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