In a shell-and-tube heat exchanger, what is the principal purpose of providing baffles on the shell side?

Introduction / Context:
Shell-and-tube exchangers are the workhorses of process and HVAC industries. Baffles are structural and hydraulic elements on the shell side that influence heat-transfer coefficients, pressure drop, and mechanical integrity of the tube bundle.

Given Data / Assumptions:

• Single-phase shell-side flow.
• Segmental or double-segmental baffle arrangement.
• Normal design objectives: high U with acceptable pressure drop and vibration control.

Concept / Approach:
Baffles direct the shell-side fluid across the tube bundle in a zig-zag path, increasing cross-flow velocity and turbulence, which elevates the shell-side heat-transfer coefficient. They also physically support tubes, reducing vibration risks, and minimize stagnant zones and by-pass streams that would otherwise reduce effectiveness.

Step-by-Step Reasoning:

Verification / Alternative check:
Design correlations (e.g., Bell–Delaware method) explicitly include baffle spacing and leakage effects in predicting shell-side h and pressure drop.

Why Other Options Are Wrong:

• Options (a), (b), and (c) each state true but partial roles; hence the most complete answer is “All of these”.
• (e) Baffles increase, not minimize, pressure drop; designers balance heat transfer and pumping power.

Common Pitfalls:
Over-tight baffle spacing: while it raises heat transfer, it may cause excessive pressure drop and vibration; design must optimize.

Final Answer:
All of these