Empirical Correlations/Models cont'd

DOE-HDBK-3010-94

3.0 Liquids; Aqueous Solutions

massl =

masssh - massv

(3-10)

and substituted into the energy balance to develop an equation for the flashing fraction

(massv/masssh) as follows:

massv/masssh =

(Hsh - Hl)/(Hv - Hl)

(3-11)

The RF for the airborne material is assessed to be 0.3 based on an aerodynamic mass

median diameter (AMMD) of 21 m and a GSD of 3 recommended by the original

authors for the liquid droplets. If the combined ARF x RF calculated using the

correlation is less than the 7E-2 bounding value from experimental data for less than

100 oC superheat, the 7E-2 value is considered bounding.

Models also exist for the size distribution of the droplets formed (Gido and Koestel,

November 1978, Brown and York, 1962). Gido and Koestel (November 1978) base

their model upon the fact that drops with center-to-surface temperature differences of

<5o K do not fragment. Their model requires evaluation of many parameters such as

drop density, drop surface tension, vapor density, thermal diffusion, or residence time.

Brown and York (1962) present a much simpler model:

D10

(1840 - 5.18) T/NWe

(3-12)

linear mean diameter of the droplet, m (for water or

where:

D10

aqueous solutions of low solute concentration, the linear

diameter is roughly equivalent to the AED)

temperature of the jet, F

NWe

Weber number

densitygas X velocity of jet X diameter of jet/2 surface

tension of liquid.

A conservative assumption is to assume all the excess heat is used to evaporate as

much liquid as is required to reduce the temperature to less than boiling. The non-

volatile radionuclides are assumed to remain in the liquid and the fraction of droplets

in the respirable range (droplets 10 m AED or less) determined by Brown and

York's (1962) formula is the ARF with the RF set to a value of 1.0. In as much as the

liquid temperature is just at boiling, any additional heat could reduce the size of the

liquid droplet (although it is more difficult to evaporate water from concentrated

solutions) or even generate solid salt particles with the addition of sufficient heat.

This correlation is not assessed to be suitable for most uses due to the complexity of

parameter determination.

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