EFF_FROM_NTU

This function computes exchanger thermal effectiveness from number of transfer units, heat-capacity ratio, and flow configuration. It supports standard configurations such as counterflow, parallel flow, crossflow variants, and shell-and-tube arrangements.

The governing concept is \varepsilon = f(\mathrm{NTU}, C_r, \text{subtype}).

Excel Usage

=EFF_FROM_NTU(NTU, Cr, eff_subtype, n_shell_tube)

NTU (float, required): Thermal number of transfer units (-).
Cr (float, required): Heat capacity rate ratio Cmin/Cmax (-).
eff_subtype (str, optional, default: “counterflow”): Exchanger configuration subtype (-).
n_shell_tube (int, optional, default: null): Number of shell and tube exchangers in series (-).

Returns (float): Thermal effectiveness of the exchanger (-).

Example 1: Effectiveness for parallel flow

Inputs:

NTU	Cr	eff_subtype
5	0.7	parallel

Excel formula:

=EFF_FROM_NTU(5, 0.7, "parallel")

Expected output:

0.588116

Example 2: Effectiveness for crossflow

Inputs:

NTU	Cr	eff_subtype
5	0.7	crossflow

Excel formula:

=EFF_FROM_NTU(5, 0.7, "crossflow")

Expected output:

0.844482

Example 3: Effectiveness for counterflow

Inputs:

NTU	Cr	eff_subtype
5	0.7	counterflow

Excel formula:

=EFF_FROM_NTU(5, 0.7, "counterflow")

Expected output:

0.92067

Example 4: Effectiveness for shell and tube series

Inputs:

NTU	Cr	eff_subtype	n_shell_tube
5	0.7	S&T	50

Excel formula:

=EFF_FROM_NTU(5, 0.7, "S&T", 50)

Expected output:

0.920506

Python Code

Show Code

from ht.hx import effectiveness_from_NTU as hx_effectiveness_from_NTU

def eff_from_NTU(NTU, Cr, eff_subtype='counterflow', n_shell_tube=None):
    """
    Calculate effectiveness from NTU, capacity ratio, and configuration.

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

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

    Args:
        NTU (float): Thermal number of transfer units (-).
        Cr (float): Heat capacity rate ratio Cmin/Cmax (-).
        eff_subtype (str, optional): Exchanger configuration subtype (-). Valid options: Counterflow, Parallel, Crossflow, Crossflow Approximate, Crossflow Mixed Cmin, Crossflow Mixed Cmax, Boiler, Condenser, Shell and Tube. Default is 'counterflow'.
        n_shell_tube (int, optional): Number of shell and tube exchangers in series (-). Default is None.

    Returns:
        float: Thermal effectiveness of the exchanger (-).
    """
    try:
      result = hx_effectiveness_from_NTU(NTU=NTU, Cr=Cr, subtype=eff_subtype, n_shell_tube=n_shell_tube)
      return result
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

NTU *

Thermal number of transfer units (-).

Cr *

Heat capacity rate ratio Cmin/Cmax (-).

eff_subtype

Exchanger configuration subtype (-).

n_shell_tube

Number of shell and tube exchangers in series (-).