Nucleation region

The nucleate region is the one of interest in most plant design as previously described for plain tube boiling. The critical temperature difference curves have been determined experimentally for a reasonable number of fluids and should be used whenever possible. 

Figure 6. Current vs. time, and transmittance-decrease vs. time plots for n-heptyl-viologen reduction obtained on a clean (top) and ion-beam modified (bottom) ITO, MPOTE. Current increases with (tinted in the nucleation region, and then decreases, while the absorbance changes linearly. Rates of nucleation are enhanced on the modified surface. [n-HV ] = 10 3M, 0.1 M KHP. Potential steps are indicated with each plot.

By plotting Hc/Ms versus (2K-JV/M m) for different temperatures the unknown parameters 7Veff and r0 (the latter is a measure of the width of the nucleation region) can be determined from the inverse slope and from the intersection of the straight line with the horizontal axis, respectively. Results obtained by Durst and Kronmuller (1987) for aligned sintered Nd15Fe77B8 permanent magnets in the temperature... 

Fig. 19. Illustration of typical sigmoidal curve in d /dN vs AK plot of FCP data. Three regions are identified region I associated with damage nucleation region II associated with subcritical crack growth and region III associated with unstable, rapid failure.

Figure 4.2 Nucleation at polymorphic mode and frozen-in concentration profile (a) dependence of the Gibbs free energy per atom on the compositions of the old and new phases and (b) frozen-in profile in the diffusion couple, approximately linear in the nucleation region.

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