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Dittus-Boelter Equation for Heating:
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The Dittus-Boelter equation is an empirical correlation used to calculate the Nusselt number for turbulent flow in smooth circular pipes. The heating version (with exponent 0.4 for Prandtl number) is used when the fluid is being heated.
The calculator uses the Dittus-Boelter equation for heating:
Where:
Explanation: This empirical correlation relates the convective heat transfer coefficient (through Nu) to flow conditions (Re) and fluid properties (Pr) for turbulent flow in pipes.
Details: The Nusselt number is crucial for determining convective heat transfer rates in engineering applications, particularly in heat exchanger design, HVAC systems, and various thermal engineering problems.
Tips: Enter Reynolds number and Prandtl number as positive dimensionless values. The equation is valid for turbulent flow (Re > 4000) in smooth circular pipes.
Q1: What is the range of validity for this equation?
A: The Dittus-Boelter equation is valid for turbulent flow (Re > 4000) in smooth circular pipes with 0.6 ≤ Pr ≤ 160 and moderate temperature differences.
Q2: What's the difference between heating and cooling versions?
A: For heating, the Prandtl number exponent is 0.4; for cooling, it's 0.3 to account for different boundary layer development.
Q3: When should I use this equation?
A: Use for preliminary design calculations of heat transfer in turbulent pipe flow with moderate temperature differences and common fluids.
Q4: What are the limitations of this equation?
A: Not suitable for very high Prandtl numbers, large temperature differences, rough pipes, or non-circular conduits without modification.
Q5: Are there more accurate correlations available?
A: Yes, the Gnielinski correlation and Petukhov equation provide better accuracy for a wider range of conditions but are more complex.