ABSTRACT
For comparison purposes, a calculation is performed for the rate of homo-geneous droplet nucleation from a supersaturated vapor (Table 10). The equation is that from Dunning and Shipman [23]:
7. Reconciliation of Theory and Experiment
In the case of boiling, the data shows that the theory and experiment agree remarkably well. The data from Table 1B show an average value of the superheat calculated from the theory vs. the measured superheat, the ratio boiling theory/measured=0.997, with a standard deviation of ±0.03. For cavitation, the comparable figure for the theoretical and measured fracture
tensions are cavitation theory/measured=2.18±1.55 (if the values for mercury are discarded) and 9.63±19.77 (if they are included). The compa-rable figures for the nucleation of gas bubbles in water are somewhat less easily assembled, the chief difficulties being distinguishing homogeneous from heterogeneous nucleation, or indeed whether bubble nucleation is involved at all in a couple of cases, and in the effect of gas adsorption on the surface tension. Ignoring these potential complications, the theoretical calculation performed as shown in Table 9 gives a theoretical value of gas in water theory of about 1400 for gases dissolved in water at ambient temperature of 25°C. Using this as a basis, the values of the supersaturation calculated as shown above and measured by various means (pressure release, bubble train timing, and chemical generation) in situ for various gases give a ratio of gas in water theory/measured=89±107. For bubbles of N2 in various organic solvents, a much smaller value of the ratio results: gas in organics theory/measured= 5±2.76.
