NU_PLATE_KUMAR

This function computes Nusselt number for single-phase flow in well-designed chevron plate heat exchangers using the Kumar correlation. The model uses empirical coefficients selected by Reynolds-number and angle ranges, with an optional viscosity wall correction.

A common representation is:

Nu = C_1 Re^m Pr^{0.33}\left(\frac{\mu}{\mu_{wall}}\right)^{0.17}

where the viscosity ratio term is applied when both bulk and wall viscosities are supplied. The result is a hydraulic-diameter-based Nusselt number for heat transfer estimation.

Excel Usage

=NU_PLATE_KUMAR(Re, Pr, chevron_angle, mu, mu_wall)

Re (float, required): Reynolds number with respect to hydraulic diameter of the channels (-).
Pr (float, required): Prandtl number calculated with bulk fluid properties (-).
chevron_angle (float, required): Plate chevron angle relative to flow direction (degrees).
mu (float, optional, default: null): Viscosity at bulk temperature (Pa*s).
mu_wall (float, optional, default: null): Viscosity at wall temperature (Pa*s).

Returns (float): Nusselt number with respect to hydraulic diameter, or error message if invalid.

Example 1: Example without wall correction

Inputs:

Re	Pr	chevron_angle
2000	0.7	30

Excel formula:

=NU_PLATE_KUMAR(2000, 0.7, 30)

Expected output:

47.7578

Example 2: Example with wall correction

Inputs:

Re	Pr	chevron_angle	mu	mu_wall
2000	0.7	30	0.001	0.0008

Excel formula:

=NU_PLATE_KUMAR(2000, 0.7, 30, 0.001, 0.0008)

Expected output:

49.6043

Example 3: Low Reynolds number case

Inputs:

Re	Pr	chevron_angle
300	2	45

Excel formula:

=NU_PLATE_KUMAR(300, 2, 45)

Expected output:

16.5498

Example 4: Higher Reynolds number case

Inputs:

Re	Pr	chevron_angle
5000	0.9	60

Excel formula:

=NU_PLATE_KUMAR(5000, 0.9, 60)

Expected output:

41.5623

Python Code

Show Code

from ht.conv_plate import Nu_plate_Kumar as ht_Nu_plate_Kumar

def Nu_plate_Kumar(Re, Pr, chevron_angle, mu=None, mu_wall=None):
    """
    Calculate Nusselt number for a well-designed chevron plate heat exchanger (Kumar correlation).

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

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

    Args:
        Re (float): Reynolds number with respect to hydraulic diameter of the channels (-).
        Pr (float): Prandtl number calculated with bulk fluid properties (-).
        chevron_angle (float): Plate chevron angle relative to flow direction (degrees).
        mu (float, optional): Viscosity at bulk temperature (Pa*s). Default is None.
        mu_wall (float, optional): Viscosity at wall temperature (Pa*s). Default is None.

    Returns:
        float: Nusselt number with respect to hydraulic diameter, or error message if invalid.
    """
    try:
        result = ht_Nu_plate_Kumar(
            Re=Re,
            Pr=Pr,
            chevron_angle=chevron_angle,
            mu=mu,
            mu_wall=mu_wall,
        )
        return float(result)
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

Re *

Reynolds number with respect to hydraulic diameter of the channels (-).

Pr *

Prandtl number calculated with bulk fluid properties (-).

chevron_angle *

Plate chevron angle relative to flow direction (degrees).

Viscosity at bulk temperature (Pa*s).

mu_wall

Viscosity at wall temperature (Pa*s).