Shell-and-tube baffle geometry: A “25 percent cut” segmental baffle in a shell-and-tube heat exchanger means that the baffle plate height equals what fraction of the shell inside diameter (I.D.)?

Introduction / Context:
Segmental baffles direct shell-side flow and enhance cross-flow heat transfer while supporting tubes. The “baffle cut” is a key geometric parameter influencing pressure drop, vibration, and heat transfer coefficients.

Given Data / Assumptions:

• Single-segmental baffles with a specified percentage cut.
• Cut is expressed as a fraction of shell diameter removed to create the window.
• We want the remaining baffle height across the shell.

Concept / Approach:
A 25% cut means 25% of the shell diameter is removed. The remaining baffle height is therefore 100% − 25% = 75% of the shell I.D. This height forms the cross-flow restriction and governs shell-side velocity.

Step-by-Step Solution:
Define cut = fraction of diameter removed = 0.25 D_shell.Remaining baffle height = D_shell − 0.25 D_shell = 0.75 D_shell.Thus, height equals 75% of I.D.

Verification / Alternative check:
Design texts illustrate that a 25% cut retains 75% height; common cut values are 15–45%, trading heat transfer vs. pressure drop.

Why Other Options Are Wrong:
Stating height is 25% confuses the removed portion with the remaining. Options about spacing or width mix unrelated parameters.

Common Pitfalls:

• Interchanging “cut” with “window height”.
• Ignoring that baffle spacing (longitudinal pitch) is an independent design choice.

Final Answer:
75% of the shell I.D.