Standards & handbook references
- TEMA-2019 (Chinese translation) — condensation and exchanger practice (provenance).
- H. Obana, Heat Exchanger Design Handbook — falling-film lineage (provenance).
- Related workflow: /tools/steam-calculator — saturation T→P and hfg for shell-side checks.
Model assumptions
- Default plant preset: Ø57×3.5 mm, 12 m tube, λ = 40 kcal/(m·h·°C), handbook fouling ro / ri.
- Liquid-film line load Γ uses the liquid film load unit category; dynamic viscosity μ uses dynamic viscosity — same kg/(m·h) symbol, different engineering meaning.
- Shell-side saturated steam and condensate-film properties can be auto-filled via IAPWS-IF97 @ tf; tube-side evaporating liquid properties are manual inputs — this tool does not IAPWS-fill process liquor.
- The UI follows eight numbered sections aligned to the handbook calculation sheet; intermediate quantities in §1/2/4/5/7 are collapsed by default and can be expanded from the section header.
Sharing
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Excel template cross-check (reference)
- Live cross-check output has moved to this engineering note section so the calculator page keeps the eight-section formulas and live results on the first screen. Inputs still recompute locally as you edit.
- Tube count: §2 offers Inner Di / Outer Do / Mean Dm / Custom. Alumina preset uses Inner Di → N = 1221 (matches template); No = 1071 (outer Do); Nm uses log-mean Dm. Expand §2 intermediate rows for all three reverse-calculations. Γ and m₀ follow the effective N.
- Display precision: Cell display values (e.g. μf = 0.68, κf = 0.59) may differ from internal digits by ~0.1–1% on ho, ReL, or U while Γ and m₀ agree — not a formula defect.
- Prefer IAPWS-IF97 @ tf for shell film props, or enter μ/κ with 3–4 significant figures when reproducing spreadsheet numbers by hand.
Frequently asked questions
- Why separate liquid film load from dynamic viscosity?
- Both may display kg/(m·h), but Γ is mass flux per wetted perimeter while μ is a transport property. Separate unit categories prevent picking viscosity units for film-load rows.
- Why are tube-side ρ1, μ1, c1, and κ1 manual inputs?
- The handbook spreadsheet case supplies process-liquid properties as given data, separate from IAPWS shell steam props. Expand §5 intermediate rows to edit them.
- Why does the Excel cross-check show “display precision” notes?
- When Γ and m₀ match but ho, Ref, or U differ by ~0.1–1%, the template likely used higher-precision μ/κ internally while cells display 0.68 / 0.59. This is expected when typing displayed values — not a formula bug. Use IAPWS auto props or more significant digits, or read the cross-check badge.
- Why does the alumina template show N = 1221 tubes while No from area is 1071?
- The handbook case back-calculates tube count from area A using inner diameter Di: Ni = ROUNDUP(A/(π·L·Di)) = 1221; No = 1071 uses outer Do. §2 lets you pick Inner Di / Outer Do / Mean Dm / Custom; the alumina preset defaults to Inner Di. Γ and m₀ follow the effective N. Expand §2 intermediate rows for No/Ni/Nm side-by-side.
Extended copy on this page (headings, references, assumptions, FAQs) may be drafted or localized with AI assistance; engineering judgment and governing codes still apply. Numerical models run locally in your browser as implemented. For contract-critical work, cite primary standards and qualified review.