Based on the input data defined in Section 251, there are a number of calculations required to be able to compute the various correction factors, flow areas, surfaces, and so on, as needed for the ultimate purpose of determining the shell-side heat transfer coefficient and pressure drop. These auxiliary calculations are defined in this section.

A. Segmental baffle window calculations

Referring to Figure 1, which illustrates the basic segmental baffle geometry in relation to the tube field, we calculate first the centri-angle of the baffle cut intersection with the inside shell wall, θ_ds and the angle intersecting the diameter D_ctl, that is, the circle through the centers of the outermost tubes, D_ctl = D_otl – D_t (see Section 251).

\[\label{eq1} \theta_{ds} = 2 \cos^{-1} \left[1 - 2\left(\frac{B_{c}}{100}\right)\right] \quad(\mbox{deg})\tag{1}\]

\[\label{eq2} \theta_{ctl} = 2 \cos^{-1} \left\{\frac{D_{s}}{D_{ctl}}\left[1 - 2\left(\frac{B_{c}}{100}\right)\right]\right\}\quad(\mbox{deg})\tag{2}\]