Code Manual for CONTAIN 2.0 - Federation of American Scientists

then expanded to first order around the interface temperature T’i~from the last iteration. For
example, the saturation vapor pressure at the interface Pvj~is approximated as
Pvi~ = P,T: + ()
@,(Ti) (Tif- ‘i)
dT
The energy balance equation can then be represented, after some rearrangement, in the form
(10-154)
q’ - bAT + a(AT)2 = hmAT (10-155)
where AT = Ti~- TW.To give an example of the coefficients, for condensing conditions and Aq =
O,these have the form
q’ = ‘c(Tb-TW)‘j’ (%,b-$)+ qrad+qaer+qeXt‘(jaer ‘jext~t
b = hC+(j’ +j&r+j~Xt)c~,4 +MvK~ dT ,
dmf)c,pt
a = MVK g dT ‘
‘s(T;f)(hvb_fi~
k the above, hCis the convective heat transfer coefficient, ~,b is
c~,~is the liquid specific heat at T~PAlso,
fit = hf(T:) - c~,,(T:f-T~)
1
J‘ = MvKg (Pv,b- ‘pS(T:f) (T;f_TW)
‘s(T;f)) + dT
[
(10-156)
(10-157)
(10-158)
the vapor enthalpy in the bulk gas;
(10-159)
(10-160)
Equation (10-155) is solved for Ti~and the assumed conditions (condensing or evaporating, and in
some cases, dry surface or wet) are checked for consistency. If the assumed conditions are not
consistent, an alternative is selected and Ti~recalculated until consistent conditions are found. The
iterations are continued until consistency and convergence in Ti~is found. In the event the surface
is wet initially but dries out during the CONTAIN timestep, time-averaged heat transfer and a timeaveraged
Tifweighting the wet and dry periods are calculated.
10.7 Heat Transfer Control ODtions
The code allows the user to deactivate the heat transfer across certain interfaces on a cell-by-cell
basis through the use of an optional keyword HT-TRAN followed by five user-defined flags (see
Section 14.3.1.6). The heat transfer flags correspond, in the order given, to
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