Thermodynamic region

Eig. 2. The thermodynamic regions of corrosion, immunity, and passivation of iron in an iron—water system assuming passivation by a film of Ee202 (H)-... 

Fig. 2 and 3 showed that increasing gas flow rate Qg) and temperature (7) at 500 rpm rotation speed (TV), will increase the acetaldehyde conversion. Fig. 2 also showed that the reaction is in kinetic regime at low temperature, while at higher temperature (Fig.3), the reaction approach the equilibrium condition or in thermodynamic region. 

The pinch divides the system into two distinct thermodynamic regions. The region above the pinch can be considered a heat sink, with heat flowing into it, from the hot utility, but not out of it. Below the pinch the converse is true. Heat flows out of the region to the cold utility. No heat flows across the pinch. 

In the thermodynamic region, Ivey found only one set of data on water and one on nitrogen, which indicated that... 

For liquid metal boiling, however, Eq. (2-67) showed poor agreement with the experimental results of Bobrovich et al. (1967). In Ivey s correlations, it is expected that the thermodynamic region will not normally be applicable to liquid metals, because their bubble growth is very rarely thermally controlled. Consequently, in this case, Eq. (2-64) for the hydrodynamic region is applicable and is combined with Eq. (2-62), leaving the ratio [tj(tw + td) as a variable ... 

Figure 4.14 Schematic representation of the classical activation energy AG for different reaction energies AE. (a) is the normal thermodynamic region, (b) is the activationless reaction and (c) is the iinverted> region...

Fig. 8. Reversible-thermodynamic regions of the calibration curves from Fig. 7 drawn in detail up to the point of inflexion (ordinate is not normalized here, the intersections with the ordinate are equal to —In r0(T), obtained by a spline extrapolation)...

We shall show later that these simple equations provide a coherent explanation for water diffusion from the supercooled region to the boiling point, thereby showing that at least in this thermodynamic region the hydrogen bond plays an important role. 

Simulations essentially extend possibility to study supercooled liquid water, as crystallization may be suppressed. However, there is no water model, which adequately reproduces phase diagram of water and its properties even in the thermodynamic region, where experimental data are available. In such situation, only comparative analysis of the results, obtained for various water models, can give information, relevant for the behaviour of real water in supercooled region. Additional complication appears due to the necessity to use sophisticated simulation methods, appropriate for the studies of the phase transitions, such as Monte Carlo simulations in the grand canonical or in the Gibbs ensemble (see Refs.7,16 for more details). Note, that simulations in the simple constant-volume or constant-pressure ensembles, widely used in the studies of supercooled water (see, for example Refs. 17,18), are not appropriate for the location of the phase transitions. 

Phase, thermodynamic Region of the space specified by the thermodynamic degrees of freedom of system separated from the remainder by a clearly defined surface and within which the thermodynamic properties differ fi om those of the remainder. 

FIGURE I4.I. Potential-pH diagram for F -H20 system at 2S°C. The area between the lines a and b represents the thermodynamic region of the stability of water [9]. (With permission from M.POURBAIX, Atlas of Electrochemical Equilibria in Aqueous Solutions, NACE and CEBELCOR.)... 

The thermodynamic region of the stable iron oxide has been shown in Fig. 3.2 in Chapter 3. 

Figure 14.19 illustrates the range of t licability of the present representation of the thermal conductivity as well as die estimated uncertainty in various thermodynamic regions. The correlation can be used up to 625 K and 70 MPa. At pressures below 10 bars, the representation can be used to estimate die thermal conductivity up to 1000 K. The lower temperature limit in die gaseous phase is 225 K, while the overall correlation can be used to estimate the liquid phase diermal conductivity down to 100 K. 

Fig. 9. Division of the Baltic Sea into 31 thermodynamic regions (from Gustafsson et al., 1998).

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