Dittus–Boelter Calculator
Water being heated in a 25 mm tube at Re = 50,000 and Pr = 5 has a film coefficient of 6035.36 W/(m²·K).
6035.3586481669 W/(m²·K)
Full answer, then cut to fewer decimals (not rounded):
- 6035.3586481669 W/(m²·K)
- 6035.358648166 W/(m²·K)
- 6035.35864816 W/(m²·K)
- 6035.3586481 W/(m²·K)
- 6035.358648 W/(m²·K)
- 6035.35864 W/(m²·K)
- 6035.3586 W/(m²·K)
- 6035.358 W/(m²·K)
- 6035.35 W/(m²·K)
- 6035.3 W/(m²·K)
- Nusselt number Nu
- 251.473277
- Validity
- within 10⁴ ≤ Re, 0.6 ≤ Pr ≤ 160
Step-by-step solution
- Nu = 0.023 Re^0.8 Pr^0.4 = 0.023 × 50000^0.8 × 5^0.4 = 251.473277
- h = Nu k / D = 251.473277 × 0.6 ÷ 0.025 = 6035.358648 W/(m²·K)
Dittus–Boelter Formula
Nu = 0.023 Re^0.8 Prⁿ
n = 0.4 when the fluid is heated, 0.3 when cooled; h = Nu k/D
Worked Example
Water being heated at Re = 50,000 and Pr = 5 in a 25 mm tube:
- Nu = 0.023 Re^0.8 Pr^0.4 = 0.023 × 50000^0.8 × 5^0.4 = 251.473277
- h = Nu k / D = 251.473277 × 0.6 ÷ 0.025 = 6035.358648 W/(m²·K)
Validity: within 10⁴ ≤ Re, 0.6 ≤ Pr ≤ 160
GATE tip
The h ∝ V^0.8 and D^−0.2 scaling appears in many GATE questions without numbers: work with ratios.
Frequently asked questions
How does h change if velocity doubles?
h ∝ Re^0.8, so it rises by 2^0.8 = 1.74 times.
How does h depend on tube diameter at the same mass flow?
At constant mass flow Re ∝ 1/D, so h ∝ D^−1.8.
Sources
- The International System of Units (SI), 9th edition (SI Brochure), Bureau International des Poids et Mesures .
Last reviewed: . Factors are stored exactly and computed with 50-digit decimal arithmetic. See how we verify conversion factors.
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APA
Scientific Converters. (2026, October 15). Dittus–Boelter Calculator. Retrieved October 29, 2026, from https://scientificconverters.com/calculators/dittus-boelter-calculator/
IEEE
Scientific Converters, "Dittus–Boelter Calculator," scientificconverters.com. Accessed: Oct. 29, 2026. [Online]. Available: https://scientificconverters.com/calculators/dittus-boelter-calculator/