multivariate production systems optimization - Stanford University
multivariate production systems optimization - Stanford University
multivariate production systems optimization - Stanford University
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3.4.4 Annular-Mist Flow Regime<br />
For modeling the annular-mist flow regime, Aziz et al. (1972) used the procedure<br />
developed by Duns and Ros (1963). Duns and Ros assumed that the high gas velocity of<br />
the annular-mist region would allow no slippage to occur between the phases. The mixture<br />
density used to calculate the density component is, therefore, the no-slip density, ρNS . The<br />
expression for the density component is<br />
dP =<br />
dZ HH<br />
g<br />
gC ρNS = g<br />
gC ρL λL + ρG λG<br />
32<br />
(3.70)<br />
The friction component for the annular-mist region is based solely on the gas phase<br />
and is given by<br />
dP<br />
dZ F<br />
= fM<br />
2<br />
ρG VSG 2 gC D<br />
where the Moody friction factor is based on the Reynold’s number of the gas<br />
Re = ρG VSG D<br />
μG<br />
Duns and Ros (1963) gave special treatment to the manner that the relative<br />
roughness was determined. They discovered that the pipe roughness was altered by the<br />
thin layer of liquid on the wall of the pipe. Two variables are used to characterize this<br />
effect. The first is a form of the Weber number<br />
NWE = ρG<br />
2<br />
VSG ε<br />
σL<br />
and the second is dimensionless number based on liquid viscosity<br />
Nμ = μL<br />
ρL σL ε<br />
(3.71)<br />
(3.72)<br />
(3.73)<br />
(3.74)<br />
Duns and Ros (1963) proposed the following relationship to model the relative roughness:<br />
NWE Nμ ≤ 0.005<br />
ε =<br />
0.0749 σL<br />
D<br />
2<br />
ρG VSG D<br />
(3.75)