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multivariate production systems optimization - Stanford University

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NV ≤ 18 25<br />

18 < NV < 250 69 NV -0.35<br />

250 ≤ NV<br />

10<br />

Having obtained the liquid holdup, the hydrostatic head component of the total pressure<br />

gradient is<br />

31<br />

dP g<br />

=<br />

dZ HH gC ρL HL + ρG HG = g<br />

gC ρS<br />

The friction component in slug flow is evaluated as<br />

dP =<br />

dZ F<br />

fM<br />

2<br />

ρL HL VM 2 gC D<br />

where the Moody friction is obtained using a Reynold’s number of<br />

Re = ρL VM D<br />

μL<br />

(3.62)<br />

(3.63)<br />

(3.64)<br />

(3.65)<br />

(3.66)<br />

(3.67)<br />

As in the bubble flow regime, the acceleration component was considered to be negligible<br />

in the slug flow regime. Therefore, the total pressure gradient for the slug flow regime is<br />

given by<br />

3.4.3 Transition Flow Regime<br />

dP =<br />

dZ SLUG<br />

dP +<br />

dZ HH<br />

dP<br />

dZ F<br />

(3.68)<br />

The transition flow region is, as the name indicates, a region of transition between the slug<br />

flow region and the annular-mist flow region. When flow occurs within the transition<br />

region, the pressure gradient is obtained by performing a linear interpolation between the<br />

slug and annular-mist regions, as suggested by Duns and Ros (1963). The interpolation is<br />

performed as follows:<br />

dP =<br />

dZ TRANS<br />

N3 - NX<br />

N3 - N2<br />

dP +<br />

dZ SLUG<br />

NX - N2<br />

N3 - N2<br />

dP<br />

dZ MIST<br />

(3.69)

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