Home
Back
Nusselt Number Formula:
| From: | To: |
The Nusselt Number represents the ratio of convective to conductive heat transfer at a boundary in a fluid. For a horizontal plate with constant wall temperature, this specific correlation provides an accurate estimation of heat transfer characteristics in natural convection scenarios.
The calculator uses the Nusselt Number formula:
Where:
Explanation: This correlation specifically applies to natural convection heat transfer from horizontal plates with constant wall temperature, where the product of Grashof and Prandtl numbers falls within the laminar flow regime.
Details: Accurate Nusselt Number estimation is crucial for designing heat transfer systems involving horizontal surfaces, predicting heat transfer rates, and optimizing thermal performance in various engineering applications including electronics cooling, HVAC systems, and industrial heat exchangers.
Tips: Enter Grashof Number and Prandtl Number as positive dimensionless values. Ensure the input values are within the valid range for this correlation (typically for laminar natural convection flows).
Q1: What is the range of validity for this correlation?
A: This correlation is valid for natural convection from horizontal plates with constant wall temperature in the laminar flow regime, typically for Gr×Pr values between 10^4 and 10^7.
Q2: How does wall temperature affect the Nusselt Number?
A: For constant wall temperature conditions, the temperature difference between the plate and ambient fluid drives the natural convection flow, directly influencing the Grashof number and consequently the Nusselt number.
Q3: What are typical values for Grashof and Prandtl numbers?
A: Grashof numbers typically range from 10^4 to 10^9 for natural convection, while Prandtl numbers range from 0.7 (air) to large values for oils (up to 100,000).
Q4: Can this correlation be used for turbulent flow?
A: No, this specific correlation is designed for laminar flow conditions. Different correlations exist for turbulent natural convection from horizontal plates.
Q5: How does plate orientation affect the Nusselt Number?
A: Plate orientation significantly affects natural convection patterns. Horizontal plates (facing upward or downward) have different flow characteristics and heat transfer coefficients compared to vertical plates, requiring specific correlations for each orientation.