Shell-side equivalent diameter for a square-pitch shell-and-tube heat exchanger is defined by (where P = pitch, d = tube outer diameter)?
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Answer: A. 4(P2 – πd2/4)/πd
Explanation
Equivalent diameter calculations for shell-side flow account for the net flow area and wetted perimeter per unit length. Square-pitch tube arrangements enclose a specific fluid flow cross-section bounded by tube outer diameters. Mathematical derivation using four times the net flow area divided by wetted perimeter yields this exact formula. Shell-side equivalent diameter is used in Reynolds number calculations to determine heat transfer and friction coefficients. Square pitch places tubes in aligned rows, creating distinct flow channels compared to triangular pitch layouts. Wetted perimeter includes both the outer surface of the tubes and the internal perimeter of the enclosing shell.
Thermal designers calculate shell-side equivalent diameters to accurately predict shell-side heat transfer coefficients. Shell-and-tube exchangers handling viscous fluids often use square pitch to facilitate mechanical cleaning lanes. Engineering design manuals provide these standard geometric equations for various tube bundle configurations. Formulations missing pi or square terms fail to compute the correct hydraulic cross-sectional flow area. Inverting area and perimeter terms introduces dimensional errors in shell-side Reynolds number calculations. Alternative algebraic expressions that omit fourfold multipliers do not conform to standard hydraulic diameter definitions.
- Subject
- Engineering
- Category
- Chemical Engineering
- Topic
- —
- Difficulty
- medium
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