Temperature, conversion factors critical

The parameter determined by integration of the stress/strain history is the critical thermomechanical conversion factor, fic- As noted both in experiments [5] and in simulations [6], drawing is destabilised at a temperature of 50-60°C, i.e. within the range for which data were measured. Figure 4 shows that despite experimental and analytical uncertainties provides a very effective index for the plane stress fracture resistance Wpi they are related by a monotonic and, indeed, quite linear relationship. Figures 5 and 6 illustrate the robusmess of the procedure in that neither the initial temperature of the simulation nor the strain rate chosen to characterise plane stress separation unduly influences the result. 

The sensitivity of the stability ratio to chemical or particle interaction factors can be illustrated by an examination of the model expression for Wn in Eq. 6.75. For example, if temperature and the particle interaction parameters are fixed, then Wn will vary with the concentration, c (also included in /c), of Z-Z electrolyte. At low values of c, k is also small, and the first equality in Eq. 6.75 indicates that Wu will take on its largest values. (Decreasing c also provokes an increase in dm because of Eq. 6.73, but this effect is dominated by that of k.40) Conversely, as c increases, the value of Wu will drop until it achieves its minimum, Wn = 1.0, when Z dm = 2 (Eq. 6.75). At this concentration, termed the critical coagulation concentration (ccc), or flocculation value, the flocculation process has become transport-controlled and therefore is rapid. Thus in general... 

Figure 3.62 shows the temperature field of a quarter of the radial section of the reactor before the reaction firing. Combining the values of Tq, T, and Bi results in an effective cooling of the reactor near the walls during the initial instants of the reaction (T = 0 — 0.05). In Fig. 3.63 is shown the temperature field when the dimensionless time ranges between T = 0.05 and T = 0.11. Here, the reaction runaway starts and we can observe that an important temperature enhancement occurs at the reactor centre, at the same time the reactant conversion increases (Fig. 3.64). The evolution of the reaction firing and propagation characterize this process as a very fast process. We can appreciate in real time that the reaction is completed in 10 s. It is true that the consideration of isothermal walls can be criticized but it is important to notice that the wall temperature is not a determining factor in the process evolution when the right input temperature and the right input concentrations of reactants have been selected.

The third stage in the reaction represents conversion of Alb to Ale by growth of individual units to a size displaying solid-state behavior. At 25°C the critical level for A for Ale formation was near 1.30 kcal. Table IV summarizes the affinity data for all the experiments considered here. The reaction affinities are affected by pH, temperature and rate of Af addition, and these factors need to be considered in any interpretation of the data. 

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