Critical saturation

Wojtan L, ReveUin R, Thome JR (2006) Investigation of saturated critical heat flux in a single, uniformly heated microchannel. Exp Thermal Fluid Sd 30 765-774... 

Ivey and Morris (1962) reported the ratio of subcooled critical flux to saturated critical flux of pool boiling in water, ethyl alcohol, ammonia, carbon tetrachloride, and isooctane for pressures from 4.5 to 500 psia (0.3 to 34 X 105 Pa) as... 

Revellin, R., Thome, J.R., Bejan, A. and Bonjour, J., Constractal Tree-Shaped Microchaimel Networks for Maximizing the Saturated Critical Heat Flux, Int. J. of Thermal Sciences, 48, 342-352, (2009). 

If at all possible, you should not inject higher-molecular-weight compounds from 100 % aqueous solutions. If this is not possible, perhaps because you have to observe some regulations, you must saturate critical surfaces prior to the injection or try the above-mentioned pieces of advice. 

B. Agostini, J. R. Thome, M. Fabbri, D. Calmi, U. Kloter, B. Michel, High heat flux flow boiling in silicon multimicrochannels Part 111 - Saturated critical heat flux of R236fa and two-phase pressure drops, Int. J. Heat Mass Transfer, 2008, 53, 5426-5442. 

For our needs, the saturation pressure of a mixture will be defined as the vapor pressure of a pure component that has the same critical constants as the mixture ( JT... 

The initial temperature of a gas condensate lies between the critical temperature and the cricondotherm. The fluid therefore exists at initial conditions in the reservoir as a gas, but on pressure depletion the dew point line is reached, at which point liquids condense in the reservoir. As can be seen from Figure 5.22, the volume percentage of liquids is low, typically insufficient for the saturation of the liquid in the pore space to reach the critical saturation beyond which the liquid phase becomes mobile. These... 

The producing gas oil ratio starts at the solution GOR, decreases until the critical gas saturation is reached, and then increases rapidly as the liberated gas is produced into the wells, either directly as it is liberated, or pulled into the producing wells from the secondary gas cap. The secondary gas cap expands with time, as more gas is liberated, and therefore moves closer to the producing wells, increasing the likelihood of gas being pulled In from the secondary gas cap. 

In addition to the mobihty control characteristics of surfactants, critical issues in gas mobihty control processes are surfactant salinity tolerance, hydrolytic stabihty under reservoir conditions, surfactant propagation through the reservoir, and foam stabihty in the presence of cmde oil saturations. 

Va.por Pressure. Vapor pressure is one of the most fundamental properties of steam. Eigure 1 shows the vapor pressure as a function of temperature for temperatures between the melting point of water and the critical point. This line is called the saturation line. Liquid at the saturation line is called saturated Hquid Hquid below the saturation line is called subcooled. Similarly, steam at the saturation line is saturated steam steam at higher temperature is superheated. Properties of the Hquid and vapor converge at the critical point, such that at temperatures above the critical point, there is only one fluid. Along the saturation line, the fraction of the fluid that is vapor is defined by its quaHty, which ranges from 0 to 100% steam. 

Density. The density of saturated water and steam is shown in Figure 2 as a function of temperature on the saturation line. As the temperature approaches the critical point, the densities of the Hquid and vapor phase approach each other. This fact is cmcial to boiler constmction and steam purity because the efficiency of separation of water from steam depends on the density difference. 

Fig. 2. Density on saturation line of ( ) water and (----) steam, where ( ) represents the critical point.

Along the saturation line and the critical isobar (22.1 MPa (3205 psi)), the dielectric constant of water declines with temperature (see Fig. 10). In the last 24°C below the critical point, the dielectric constant drops precipitously from 14.49 to 4.77 in the next 5°C, it further declines to 2.53 and by 400°C it has declined to 1.86. In the region of the critical point, the dielectric constant of water becomes similar to the dielectric constants of typical organic solvents (Table 6). The solubiHty of organic materials increases markedly in the region near the critical point, and the solubiHty of salts tends to decline as the temperature increases toward the critical temperature. 

For temperatures below the vapor—Hquid critical temperature, isotherms to the left of the Hquid saturation curve (see Fig. 3) represent states of... 

In each of these expressions, ie, the Soave-Redhch-Kwong, 9gj j (eq. 34), Peng-Robinson, 9pj (eq. 35), and Harmens, 9 (eq. 36), parameter 9, different for each equation, depends on temperature. Numerical values for b and 9(7) are deterrnined for a given substance by subjecting the equation of state to the critical derivative constraints of equation 20 and by requiring the equation to reproduce values of the vapor—Hquid saturation pressure,... 

Some values of physical properties of CO2 appear in Table 1. An excellent pressure—enthalpy diagram (a large Mohier diagram) over 260 to 773 K and 70—20,000 kPa (10—2,900 psi) is available (1). The thermodynamic properties of saturated carbon dioxide vapor and Hquid from 178 to the critical point,... 

The equations given predict vapor behavior to high degrees of accuracy but tend to give poor results near and within the Hquid region. The compressibihty factor can be used to accurately determine gas volumes when used in conjunction with a virial expansion or an equation such as equation 53 (77). However, the prediction of saturated Hquid volume and density requires another technique. A correlation was found in 1958 between the critical compressibihty factor and reduced density, based on inert gases. From this correlation an equation for normal and polar substances was developed (78) ... 

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