Pressure Drop Prediction by Interpolation

Interpolation of pressure drop data is more accurate and reliable than correlation prediction. However, it requires that an interpolation chart be available, and is difflcult to computerize. 

For all charts (random, structured, and grid packings), the ordinate of the correlation is the capacity parameter, given by 

v is the kinematic viscosity of the liquid. [/Vote The kinematic viscosity (centistokes) is obtained by dividing the dynamic viscosity (centipoises) by the specific gravity, not by the liquid den-shy).l Cs is the C-factor, i.e., the superficial gas velocity corrected for vapor and liquid densities, given by 

Fp is the packing factor, which is an empirical factor characteristic of the packing size and shape. The packing factor to be used is marked on each GPDC interpolation chart in Chap. 10. Table 10.1 lists the values and sources of these packing factors. 

Flood and maximum operational capacity (MOO data are also plotted on the GPDC interpolation charts, uid the charts can be used fw interpolating these. Where flood and MOC data are absent, Eqs. (8.1) Euid (8.10) can he used for inferring flood points and MOCs fitmi pressure drop data on the chetrts. 

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A weak link in the correlation is the packing pressure drop prediction. Inaccurate pressure drop prediction procedures will lead to inaccurate flood-point predictions using this correlation. For best results, the author recommends applying Eq. (8.1) together with pressure drop predictions by interpolation (Sec. 8.2.9). 

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