Evaporation/condensation process

At first we tried to explain the phenomenon on the base of the existence of the difference between the saturated vapor pressures above two menisci in dead-end capillary [12]. It results in the evaporation of a liquid from the meniscus of smaller curvature ( classical capillary imbibition) and the condensation of its vapor upon the meniscus of larger curvature originally existed due to capillary condensation. We worked out the mathematical description of both gas-vapor diffusion and evaporation-condensation processes in cone s channel. Solving the system of differential equations for evaporation-condensation processes, we ve derived the formula for the dependence of top s (or inner) liquid column growth on time. But the calculated curves for the kinetics of inner column s length are 1-2 orders of magnitude smaller than the experimental ones [12]. 

The process can take one of two forms. In one, the sample and liquid are shaken (or otherwise agitated) together in the same container, the resultant mixture filtered, and the filtrate, which then contains the analyte, collected. In the other, fresh liquid is continuously cycled over a period of hours through the solid sample via a continuous evaporation-condensation process (that usually does not require an extra filtration step), and the liquid is collected. This latter method is known as a Soxhlet extraction. Soxhlet extraction will be discussed in more detail in Chapter 11. 

Clearly this is a very interesting problem and of great practical relevance, very well suited to Monte Carlo simulation. At the same time, simulations of such problems have just only begun. In the context of crystal growth kinetics, models where evaporation-condensation processes compete with surface diffusion processes have occasionally been considered before . But many related processes can be envisaged which have not yet been studied at all. 

Of special interest in stable isotope geochemistry are evaporation-condensation processes, because differences in the vapour pressures of isotopic compounds lead to significant isotope fractionations. For example, from the vapour pressure data for water given in Table 1.2, it is evident that the lighter molecnlar species are preferentially enriched in the vaponr phase, the extent depending upon the temperature. Such an isotopic separation process can be treated theoretically in terms of fractional distillation or condensation under equilibrium conditions as is expressed by the Rayleigh (1896) equation. For a condensation process, this equation is... 

After equilibrating the system, we accumulated the configurations for 997 ps (argon), 300 ps (methanol) or 375 ps (water), from which we study dynamic properties concerning evaporation-condensation processes. 

The investigation of microscale heat transfer involves the implementation of experimental techniques at the microscale level. Few decades ago this was almost impossible for many areas to access to measurements at the microscale level. The parameters governing the evaporation/condensation process have a localised effect necessitating measurement of velocity, temperature, heat flux on the microscale. 

Refrigerants absorb heat not wanted or needed and reject it elsewhere. Heat is removed from the system by evaporation of a liquid refrigerant and is rejected by condensation of the refrigerant vapor. This evaporation-condensation process occurs in absorption, mechanical and steam Jet refrigeration systems. 

These figures also show that the influence of the initial droplet size on the vaporization rate of ammonia is fairly small, unless the droplet radius is on the order of a few hundred micrometers or larger. Ctae reason for this phenomenon is that the evaporation/condensation process within a cloud is self-controlling, with negative feedback. For instance, consider the vaporization of fairly small droplets. The vaporization of contaminant is more efficient (compared to large droplets), which causes a lower cloud temperature and a larger contaminant... 

Equation (2.144) does not take into account the heat due to phase transformation of water in the CL. This process can, in principle, be accounted for as described in Nguyen and White (1993) and Birgersson et al. (2005). Note, however, that evaporation/condensation processes include mass transfer between the liquid and vapour phases (Natarajan and Nguyen, 2001), which comphcates the problem. 

Figure 5 Chondrite-normalized REE patterns for selected cal-cium-alumimmi inclusions (CAI) from the Allende carbonaceous chondrite and refractory mineral grains (perovskite, hibonite) from the Murchison carbonaceous chondrite." The highly irregular REE patterns, including anomalies for the least refractory Ce, Eu, and Yb, are indicative of localized very high temperatures leading to complex REE evaporation/condensation processes...

The heat pipe (the operating principle is shown in Figure 2.92) is a self-contained system that uses the evaporation of a volatile liquid to transport heat. In this case, heat can be transported only by the evaporation/condensation process over the length of the pipe. Heat is only dissipated if the cold end of the pipe is cooled by a temperature control channel. The heat pipe is ideal for all the other places where temperature control channels cannot be directly accessed. Using the compact heat pipes, heat can be removed locally and can then be transferred to a geometrically favorable position. The heat pipe is therefore also suitable for tempering of slender cores and other inaccessible areas. 

At thermodynamic conditions, close to normal ones, the equilibrium vapor content of the bubble can be neglected, but it grows with temperature (or pressure reduction). In the vapor presence, the pressure and/or temperature variations inside the oscillating bubble cause evaporation-condensation processes that are accompanied by the heat exchange. In polymeric solutions, transition from liquid to vapor phase and conversely is possible only for a low-molecular solvent. The transport of the latter to the bubble-liquid interface from the bulk is controlled by the diffusion rate. In general case the equilibrium vapor pressure at the free surface of a polymeric solution is lower than that for a pure solvent If a bubble contains a vapor-gas mixture, then the vapor supply to the interface from the bubble interior is controlled by diffusion rate in the vapor-gas phase. The concentration inhomogeneity within the bubble must be accounted for if tpg > t or Pe g > 1... 

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