Open Driven System

The extent to which one must drive the system in the forward direction can he seen by calculating the lowering of the small molecule concentration, which is necessary to achieve a particular molecular weight. For the poly esterification (Eq. 2-58) one can rewrite Eq. 2-59 as 

Equation 2-65, which applies equally to A—B polymerizations, indicates that [H20] must be greatly reduced to obtain high Xn values. [H20] is inversely dependent on essentially the square of Xn since (Xn — 1) is close to Xn for large values of Xn. It is also seen that the level to which the water concentration must be lowered to achieve a particular degree of polymerization increases with increasing K and increasing initial concentration of the reactants. Table 2-6 shows the calculated [H20] values for selected values of K and Xn at 

TABLE 2-6 Effect of Water Concentration on Degree of Polymerization in Open, Driven System 

Due to stoichiometric balance between COOH and OH groups there is an average of one COOH group per molecule. Thus the water content of the reaction 

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Although reversible or equilibrium polymerizations would almost always be carried out in an irreversible manner as an open driven system, it is interesting to consider the kinetics of polymerization for the case in which the reaction is allowed to proceed in a reversible manner. 

Looking at open sorption system as an indirect heat storage, the system would look like Figure 250. The charging process is driven by the district heat input. While the district heat return flow, the condensate, is providing the low temperature heat input to the humidifier for the evaporation. 

B. Derrida, J. L. Lebowitz, andE. R. Speer, Exact large deviation functional of a stationary open driven diffusive system the asymmetric exclusion process. J. Stat. Phys. 110, 775-810 (2003). 

The corrosion rate of steel increases proportionally with temperature up to about 180°F (80°C) in open air systems. At higher temperatures, oxygen is driven from the system and corrosion rates decline significantly. The effect of dissolved oxygen on the rate of mild steel corrosion is shown in FIGURE 6-13. 

The most obvious advantage of an electroosmotic pumping system is the flow profile. Electrochromatography has the same pluglike profile that is characteristic of all other modes of CE. Although the pluglike flow is less perfect in packed columns than in open tubes, it is still more uniform than the laminar flow profile of a pressure-driven system. Consequently, the same capillary would be expected to provide higher efficiencies when used in CEC than when used in pressure-driven systems.31 35,36... 

The most important task of the operators for severe accident prevention is restoration of at least one heat removal train. The simplest but not a single way to do this is reactor cavity flooding to provide better conditions for heat transfer to radiation shielding tank water Usage of this heat sink ensures decay heat removal for a practically infinite period of time. Only two valves should be open remotely from control room to actuate corresponding passive gravity driven system... 

There are certain fundamental considerations which should be understood in relation to open recirculated systems. First is the concept of cycles of concentration. If three cups of boiling water in a tea kettle were allowed to boil away to one cup, the residual cup would contain a threefold concentration of soluble water salts, assuming that only pure steam was driven off. The water would be said to be at three cycles of concentration. 

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