NTUBES_VDI

This function estimates tube count from bundle diameter using VDI Heat Atlas correlations for specified pass count and tube layout. It is an approximate method useful for rapid sizing checks.

The calculation follows a correlation structure N = f(D_{bundle}, N_{tp}, D_o, p, \theta).

Excel Usage

=NTUBES_VDI(DBundle, Ntp, Do, pitch, angle)

DBundle (float, required): Outer diameter of tube bundle (m).
Ntp (int, required): Number of tube passes (-).
Do (float, required): Tube outer diameter (m).
pitch (float, required): Tube pitch (m).
angle (int, optional, default: 30): Tube layout angle (degrees).

Returns (int): Estimated number of tubes (-).

Example 1: VDI tube count example

Inputs:

DBundle	Ntp	Do	pitch	angle
1.184	2	0.028	0.036	30

Excel formula:

=NTUBES_VDI(1.184, 2, 0.028, 0.036, 30)

Expected output:

966

Example 2: VDI tube count with 90 degree layout

Inputs:

DBundle	Ntp	Do	pitch	angle
1.1	4	0.025	0.03125	90

Excel formula:

=NTUBES_VDI(1.1, 4, 0.025, 0.03125, 90)

Expected output:

901

Example 3: VDI tube count for small bundle

Inputs:

DBundle	Ntp	Do	pitch	angle
0.7	1	0.01905	0.025	45

Excel formula:

=NTUBES_VDI(0.7, 1, 0.01905, 0.025, 45)

Expected output:

603

Example 4: VDI tube count with six passes

Inputs:

DBundle	Ntp	Do	pitch	angle
1.3	6	0.025	0.03125	30

Excel formula:

=NTUBES_VDI(1.3, 6, 0.025, 0.03125, 30)

Expected output:

1472

Python Code

Show Code

from ht.hx import Ntubes_VDI as hx_Ntubes_VDI

def Ntubes_VDI(DBundle, Ntp, Do, pitch, angle=30):
    """
    Estimate tube count from bundle diameter using the VDI method.

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

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

    Args:
        DBundle (float): Outer diameter of tube bundle (m).
        Ntp (int): Number of tube passes (-).
        Do (float): Tube outer diameter (m).
        pitch (float): Tube pitch (m).
        angle (int, optional): Tube layout angle (degrees). Default is 30.

    Returns:
        int: Estimated number of tubes (-).
    """
    try:
        result = hx_Ntubes_VDI(DBundle=DBundle, Ntp=Ntp, Do=Do, pitch=pitch, angle=angle)
        return int(result)
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

DBundle *

Outer diameter of tube bundle (m).

Ntp *

Number of tube passes (-).

Do *

Tube outer diameter (m).

pitch *

Tube pitch (m).

angle

Tube layout angle (degrees).