Which tube layout in a shell-and-tube heat exchanger generally provides the highest heat transfer coefficient on the shell side (for a given shell size)?

Introduction / Context:
Tube layout determines tube count, crossflow geometry, and shell-side turbulence. Designers balance heat transfer, pressure drop, fouling, and cleanability when selecting layouts such as triangular, square, or rotated square pitch.

Given Data / Assumptions:

• Similar tube outside diameter and pitch ratios.
• Same shell diameter for comparison.
• Clean service comparison without unusual constraints.

Concept / Approach:
Triangular pitch packs tubes most densely, increasing velocity and turbulence for a given shell size, raising the shell-side heat transfer coefficient. Square layouts ease mechanical cleaning but have fewer tubes and lower turbulence at the same shell size.

Step-by-Step Solution:
Compare pack density: triangular > square.Higher tube count at fixed shell diameter drives higher crossflow velocity.Higher velocity and turbulence enhance heat transfer, making triangular pitch superior for heat duty (though with higher pressure drop).

Verification / Alternative check:
Standards and design texts consistently state triangular pitch provides highest shell-side coefficients but at the expense of cleanability and pressure drop.

Why Other Options Are Wrong:
Square / rotated square: lower tube density for a given shell size → lower shell-side h.Independent of layout: incorrect; layout affects both h and ΔP.Random pitch: not a standard engineered option.

Common Pitfalls:
Ignoring fouling/cleaning needs; square pitch may be preferred for mechanical cleaning even with lower h.Equating “highest heat transfer” with “best design” without considering pressure drop limits.

Final Answer:
Triangular pitch