LHV_FROM_HHV

This function converts a higher heating value into a lower heating value by removing the latent heat associated with condensing the water formed during combustion. It is appropriate when combustion products are assumed to leave with water remaining in the vapor phase instead of being fully condensed.

The conversion is:

LHV = HHV + H_{vap} N_{H_2O}

where H_{vap} is the molar enthalpy of vaporization of water used by the underlying library and N_{H_2O} is the number of water molecules produced per mole of fuel burned.

Excel Usage

=LHV_FROM_HHV(HHV, N_H_two_O)

• HHV (float, required): Higher heating value [J/mol].
• N_H_two_O (int, required): Number of water molecules produced per molecule burned.

Returns (float): Lower heating value [J/mol].

Example 1: Methanol LHV

Inputs:

HHV	N_H_two_O
-726024	2

Excel formula:

=LHV_FROM_HHV(-726024, 2)

Expected output:

-638001

Example 2: Methane LHV from HHV

Inputs:

HHV	N_H_two_O
-890604	2

Excel formula:

=LHV_FROM_HHV(-890604, 2)

Expected output:

-802581

Example 3: Propane LHV from HHV

Inputs:

HHV	N_H_two_O
-2220500	4

Excel formula:

=LHV_FROM_HHV(-2220500, 4)

Expected output:

-2044450

Python Code

Show Code

from chemicals.combustion import LHV_from_HHV

def lhv_from_hhv(HHV, N_H_two_O):
    """
    Returns the lower heating value (LHV) of a chemical given the higher heating value (HHV) and number of water molecules formed.

    See: https://chemicals.readthedocs.io/chemicals.combustion.html

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

    Args:
        HHV (float): Higher heating value [J/mol].
        N_H_two_O (int): Number of water molecules produced per molecule burned.

    Returns:
        float: Lower heating value [J/mol].
    """
    try:
        return float(LHV_from_HHV(HHV, N_H_two_O))
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

HHV *

Higher heating value [J/mol].

N_H_two_O *

Number of water molecules produced per molecule burned.