F_LMTD_FAKHERI

This function calculates the Fakheri correction factor for log-mean temperature difference in shell-and-tube heat exchangers with one or multiple shell passes. The factor adjusts ideal LMTD to account for exchanger pass arrangement.

The corrected driving force is \Delta T_{lm,\mathrm{corrected}} = F_t\,\Delta T_{lm}.

Excel Usage

=F_LMTD_FAKHERI(Thi, Tho, Tci, Tco, shells)

Thi (float, required): Hot inlet temperature (K).
Tho (float, required): Hot outlet temperature (K).
Tci (float, required): Cold inlet temperature (K).
Tco (float, required): Cold outlet temperature (K).
shells (int, optional, default: 1): Number of shell-side passes (-).

Returns (float): Log-mean temperature difference correction factor (-).

Example 1: Fakheri correction factor example

Inputs:

Tci	Tco	Thi	Tho	shells
15	85	130	110	1

Excel formula:

=F_LMTD_FAKHERI(15, 85, 130, 110, 1)

Expected output:

0.943836

Example 2: Fakheri correction factor with two shells

Inputs:

Tci	Tco	Thi	Tho	shells
20	80	140	100	2

Excel formula:

=F_LMTD_FAKHERI(20, 80, 140, 100, 2)

Expected output:

0.978933

Example 3: Fakheri correction factor with larger temperature span

Inputs:

Tci	Tco	Thi	Tho	shells
25	90	160	120	1

Excel formula:

=F_LMTD_FAKHERI(25, 90, 160, 120, 1)

Expected output:

0.931251

Example 4: Fakheri correction factor with smaller temperature span

Inputs:

Tci	Tco	Thi	Tho	shells
35	70	120	95	1

Excel formula:

=F_LMTD_FAKHERI(35, 70, 120, 95, 1)

Expected output:

0.949394

Python Code

Show Code

from ht.hx import F_LMTD_Fakheri as hx_F_LMTD_Fakheri

def F_LMTD_Fakheri(Thi, Tho, Tci, Tco, shells=1):
    """
    Compute the LMTD correction factor for shell-and-tube exchangers.

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

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

    Args:
        Thi (float): Hot inlet temperature (K).
        Tho (float): Hot outlet temperature (K).
        Tci (float): Cold inlet temperature (K).
        Tco (float): Cold outlet temperature (K).
        shells (int, optional): Number of shell-side passes (-). Default is 1.

    Returns:
        float: Log-mean temperature difference correction factor (-).
    """
    try:
        result = hx_F_LMTD_Fakheri(Thi=Thi, Tho=Tho, Tci=Tci, Tco=Tco, shells=shells)
        return result
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

Thi *

Hot inlet temperature (K).

Tho *

Hot outlet temperature (K).

Tci *

Cold inlet temperature (K).

Tco *

Cold outlet temperature (K).

shells

Number of shell-side passes (-).