R_CYLINDER

Computes conductive thermal resistance for a cylindrical wall from inner and outer diameters, conductivity, and length. This is the standard radial conduction form for pipes and cylindrical layers.

The cylinder resistance is:

R = \frac{\ln(D_o/D_i)}{2\pi Lk}

Excel Usage

=R_CYLINDER(Di, Do, k, L)

Di (float, required): Inner diameter (m).
Do (float, required): Outer diameter (m).
k (float, required): Thermal conductivity (W/m/K).
L (float, required): Length (m).

Returns (float): Thermal resistance of the cylinder (K/W).

Example 1: Example cylinder resistance

Inputs:

Di	Do	k	L
0.9	1	20	10

Excel formula:

=R_CYLINDER(0.9, 1, 20, 10)

Expected output:

0.0000838432

Example 2: Thin wall with high conductivity

Inputs:

Di	Do	k	L
0.95	1	45	5

Excel formula:

=R_CYLINDER(0.95, 1, 45, 5)

Expected output:

0.0000362826

Example 3: Short cylinder length

Inputs:

Di	Do	k	L
0.2	0.4	15	0.5

Excel formula:

=R_CYLINDER(0.2, 0.4, 15, 0.5)

Expected output:

0.014709

Example 4: Moderate dimensions and conductivity

Inputs:

Di	Do	k	L
0.5	0.8	12	2

Excel formula:

=R_CYLINDER(0.5, 0.8, 12, 2)

Expected output:

0.00311681

Python Code

Show Code

from ht.conduction import R_cylinder as ht_R_cylinder

def R_cylinder(Di, Do, k, L):
    """
    Compute thermal resistance of a cylindrical wall.

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

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

    Args:
        Di (float): Inner diameter (m).
        Do (float): Outer diameter (m).
        k (float): Thermal conductivity (W/m/K).
        L (float): Length (m).

    Returns:
        float: Thermal resistance of the cylinder (K/W).
    """
    try:
        return ht_R_cylinder(Di=Di, Do=Do, k=k, L=L)
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

Di *

Inner diameter (m).

Do *

Outer diameter (m).

k *

Thermal conductivity (W/m/K).

L *

Length (m).