Handbook of Solvents - George Wypych - ChemTech - Ventech!

7.2 Bubbles dynamics and boiling 375
Figure 7.2.10. Limiting superheat at vapor bubble
growth in polymeric solution. For all graphs K ρ = 0.7,
the symbol “o” corresponds to J� 0 = 1. [Reprinted
from Z.P. Shulman, and S.P. Levitsky, Int. J. Heat
Mass Transfer, 39, 631, Copyright 1996, the reference
52, with permission from Elsevier Science]
where the constant C can be evaluated through h from [7.2.54], [7.2.57] and [7.2.58]. Note
that since Ja < Ja0, the bubble growth rate in a polymer solution is always lower than that in a
similar one-component liquid.
The set of equations, formulated above, is closed by the equation of phase equilibrium
[7.2.37]. The temperature dependence of the pure solvent vapor pressure is described by
equation 54 0
p v0 = Aexp(-B/T).
Figure 7.2.11. Dependence of the effective Jacob number
for a vapor bubble, growing in a superheated aqueous
solution of a polymer, on the parameter G.
[Reprinted from Z.P. Shulman, and S.P. Levitsky, Int.
J. Heat Mass Transfer, 39, 631, Copyright 1996, the
reference 52, with permission from Elsevier Science]
Numerical simulations of vapor bubble growth in a superheated solution of polymer
were performed, 52 using iterative algorithm to account for the diffusion coefficient dependence
on concentration in the interval (k R,k 0). The results are reproduced in Figures
7.2.10-7.2.12,
where:
Sn Scriven number, Sn = ΔT/ΔT*
G dimensionless parameter, G = εJa0Le 1/2
Δ � T * superheat of the solution at infinity, evaluated from the condition Sn = 0.99
A characteristic feature of the liquid-vapor phase equilibrium curves for polymeric solutions
in the coordinates p, k or T, k is the existence of plateau-like domain in the region of
small polymer concentrations (k* ≤k0 ≤1). For this concentration range, the number J�a 0 can
be defined so that at 1