MCNELLY

This function computes nucleate boiling heat transfer coefficient with the McNelly correlation using fluid properties, pressure, and either excess wall temperature or heat flux.

A representative form is:

h = f\left(\rho_l, \rho_g, k_l, C_{p,l}, H_{vap}, \sigma, P, \Delta T_e\right) \; \text{or} \; h=f(\cdots,q)

It is commonly used for pool-boiling estimation when detailed property inputs are available.

Excel Usage

=MCNELLY(rhol, rhog, kl, Cpl, Hvap, sigma, P, Te, q)

rhol (float, required): Density of the liquid (kg/m^3).
rhog (float, required): Density of the produced gas (kg/m^3).
kl (float, required): Thermal conductivity of liquid (W/m/K).
Cpl (float, required): Heat capacity of liquid (J/kg/K).
Hvap (float, required): Heat of vaporization of the fluid (J/kg).
sigma (float, required): Surface tension of liquid (N/m).
P (float, required): Saturation pressure of fluid (Pa).
Te (float, optional, default: null): Excess wall temperature (K).
q (float, optional, default: null): Heat flux (W/m^2).

Returns (float): Heat transfer coefficient (W/m^2/K), or an error message if invalid.

Example 1: Water boiling with excess temperature

Inputs:

Te	P	Cpl	kl	sigma	Hvap	rhol	rhog
4.3	101325	4180	0.688	0.0588	2250000	958	0.597

Excel formula:

=MCNELLY(4.3, 101325, 4180, 0.688, 0.0588, 2250000, 958, 0.597)

Expected output:

533.806

Example 2: Water boiling with heat flux

Inputs:

q	P	Cpl	kl	sigma	Hvap	rhol	rhog
20000	101325	4180	0.688	0.0588	2250000	958	0.597

Excel formula:

=MCNELLY(20000, 101325, 4180, 0.688, 0.0588, 2250000, 958, 0.597)

Expected output:

2377.42

Example 3: Higher pressure with excess temperature

Inputs:

Te	P	Cpl	kl	sigma	Hvap	rhol	rhog
6	200000	3900	0.62	0.05	2100000	1000	1.1

Excel formula:

=MCNELLY(6, 200000, 3900, 0.62, 0.05, 2100000, 1000, 1.1)

Expected output:

1278.46

Example 4: Moderate heat flux with typical properties

Inputs:

q	P	Cpl	kl	sigma	Hvap	rhol	rhog
15000	150000	3800	0.6	0.055	2100000	980	0.9

Excel formula:

=MCNELLY(15000, 150000, 3800, 0.6, 0.055, 2100000, 980, 0.9)

Expected output:

1861.15

Python Code

Show Code

from ht.boiling_nucleic import McNelly as ht_McNelly

def McNelly(rhol, rhog, kl, Cpl, Hvap, sigma, P, Te=None, q=None):
    """
    Compute nucleate boiling heat transfer coefficient using the McNelly correlation.

    See: https://ht.readthedocs.io/en/latest/ht.boiling_nucleic.html

    This example function is provided as-is without any representation of accuracy.

    Args:
        rhol (float): Density of the liquid (kg/m^3).
        rhog (float): Density of the produced gas (kg/m^3).
        kl (float): Thermal conductivity of liquid (W/m/K).
        Cpl (float): Heat capacity of liquid (J/kg/K).
        Hvap (float): Heat of vaporization of the fluid (J/kg).
        sigma (float): Surface tension of liquid (N/m).
        P (float): Saturation pressure of fluid (Pa).
        Te (float, optional): Excess wall temperature (K). Default is None.
        q (float, optional): Heat flux (W/m^2). Default is None.

    Returns:
        float: Heat transfer coefficient (W/m^2/K), or an error message if invalid.
    """
    try:
        return ht_McNelly(
            rhol=rhol,
            rhog=rhog,
            kl=kl,
            Cpl=Cpl,
            Hvap=Hvap,
            sigma=sigma,
            P=P,
            Te=Te,
            q=q,
        )
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

rhol *

Density of the liquid (kg/m^3).

rhog *

Density of the produced gas (kg/m^3).

kl *

Thermal conductivity of liquid (W/m/K).

Cpl *

Heat capacity of liquid (J/kg/K).

Hvap *

Heat of vaporization of the fluid (J/kg).

sigma *

Surface tension of liquid (N/m).

P *

Saturation pressure of fluid (Pa).

Excess wall temperature (K).

Heat flux (W/m^2).