Enthalpy Of Evaporation To Nucleate Pool Boiling Calculator

Formula Used:

\[ \Delta H = \left( \frac{1}{Q} \times \mu_f \times \left( \frac{[g] \times (\rho_l - \rho_v)}{Y} \right)^{0.5} \times \left( \frac{C_l \times \Delta T}{C_s \times (Pr)^{1.7}} \right)^3 \right)^{0.5} \]

Heat Flux (Q):

W/m²

Dynamic Viscosity of Fluid (μf):

Pa·s

Density of Liquid (ρl):

kg/m³

Density of Vapour (ρv):

kg/m³

Surface Tension (Y):

N/m

Specific Heat of Liquid (Cl):

J/kg·K

Excess Temperature (ΔT):

Constant in Nucleate Boiling (Cs):

Prandtl Number (Pr):

Change in Enthalpy of Vaporization (ΔH):

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1. What is the Enthalpy of Evaporation to Nucleate Pool Boiling Formula?

The formula calculates the change in enthalpy of vaporization for nucleate pool boiling, which represents the energy required to transform a liquid into vapor during the boiling process. This is essential for understanding heat transfer in boiling systems.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

\( \Delta H \) — Change in Enthalpy of Vaporization (J/mol)
\( Q \) — Heat Flux (W/m²)
\( \mu_f \) — Dynamic Viscosity of Fluid (Pa·s)
\( [g] \) — Gravitational acceleration (9.80665 m/s²)
\( \rho_l \) — Density of Liquid (kg/m³)
\( \rho_v \) — Density of Vapour (kg/m³)
\( Y \) — Surface Tension (N/m)
\( C_l \) — Specific Heat of Liquid (J/kg·K)
\( \Delta T \) — Excess Temperature (K)
\( C_s \) — Constant in Nucleate Boiling
\( Pr \) — Prandtl Number

Explanation: The formula accounts for various physical properties and conditions that affect the boiling process and energy requirements for vaporization.

3. Importance of Enthalpy Calculation in Boiling

Details: Accurate calculation of enthalpy change is crucial for designing efficient heat exchange systems, predicting boiling behavior, and optimizing energy consumption in industrial processes involving phase change.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Ensure values are physically meaningful (positive values where applicable). The calculator will compute the change in enthalpy of vaporization.

5. Frequently Asked Questions (FAQ)

Q1: What is nucleate pool boiling?
A: Nucleate pool boiling is a type of boiling where bubbles form at discrete nucleation sites on a heated surface submerged in a stagnant liquid.

Q2: Why is the Prandtl number important in boiling calculations?
A: The Prandtl number represents the ratio of momentum diffusivity to thermal diffusivity, which affects heat transfer characteristics during boiling.

Q3: What factors influence the constant in nucleate boiling (Cs)?
A: The constant depends on the surface-fluid combination and surface characteristics such as roughness and wettability.

Q4: How does surface tension affect boiling?
A: Surface tension influences bubble formation, growth, and departure from the heating surface, which affects heat transfer efficiency.

Q5: What are typical values for change in enthalpy of vaporization?
A: Values vary significantly depending on the fluid and conditions. For water at atmospheric pressure, it's approximately 40.7 kJ/mol.