Why formula instead of chart lookup
The 1982 Chinese edition of Obana’s handbook (upper volume, Chapter 9, pp. 419–427) gives fouling factors referenced to TEMA tables and a chart (Fig. 9-1) relating two operating points. This tool implements the exponential law r = r₀[1 − exp(−Bθ)] (Eq. 9.17), solves r₀ from two field measurements, extrapolates to a design month, then applies flow/diameter exponents in Eq. 9.19–9.20. Chart interpolation can deviate materially from the same inputs; the calculator uses the handbook formulas only. No chart image is shown in the UI.
Model assumptions
- Time unit is the engineering month (30 d) as in the handbook worked example.
- Fouling resistance default unit h·m²·°C/kcal matches the 1982 worked tables; SI m²·K/W is available in unit pickers.
- Uf = 1/r is the fouling-resistance reciprocal only — not Uc or Ud from Eq. 9.1–9.2 unless you combine externally.
- Listing Obana (1982) and TEMA references is provenance only; not a standard endorsement.
References
- H. Obana, Heat Exchanger Design Handbook, upper volume, Petroleum Industry Press, 1st ed., 1982, Chapter 9 (fouling factors, pp. 419–427).
- TEMA fouling factors (cited in Obana; modern cross-check: TEMA standards RGP fouling resistance tables).
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FAQ
- Why do results differ from reading Fig. 9-1?
- The chart is a graphical solution of the same exponential law. Closed-form evaluation avoids interpolation and reading error; differences of tens of percent have been observed on sample points.
- Is Uf the overall heat-transfer coefficient?
- No. Uf here is 1/r for the fouling resistance only. Overall Ud still requires clean-side resistances from Eq. 9.1–9.2.
- Does data leave my browser?
- No. Calculations are client-side only.
Extended copy on this page (headings, assumptions, references, 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.