D
ispersed l
iqu
id droplet flows w
ith evaporat
ion and condensat
ion
in mult
i-component gas m
ixture made of vapor and other gas phase chem
ical spec
ies such as a
ir occur
in many eng
ineer
ing appl
icat
ions deal
ing w
ith two-phase flows. However, ex
ist
ing models are essent
ially der
ived for vapor
izat
ion occurr
ing
in sprays combust
ion. It means that the energy
is transferred from a hot gas to the l
iqu
id to produce
its phase change. Th
is
is thus a non-symmetr
ic approach as
in some s
ituat
ions the energy
is already stored
in the l
iqu
id phase and flash
ing occurs as a consequence of pressure drop.
id="sp0010">In the present paper a droplet mass transfer model is derived and is valid in any situation: evaporation, flashing and condensation. It accounts for:
id="sp0015">
istitem" id="list_l0005">- -
id="p1015">coupled heat and mass diffusion in the gas phase,
- -
id="p1020">thermodynamics of the multi-component gas mixture,
- -
id="p1025">heat diffusion inside the liquid droplet, enabling consideration of both droplet heating and cooling. These effects are important in evaporating and flashing situations respectively.
id="sp0020">The resulting model consists in an algebraic non-linear system of three equations giving the interface temperature, the mass flow rate and vapor species concentration at the interface. These interfacial variables enable computation of the mass species, momentum and energy transfer rates appearing in volume averaged two-phase flow models.
id="sp0025">Computational examples are shown with this mass transfer model embedded in a compressible two-phase flow model of Baer and Nunziato (1986) type.