A better estimate may be the Lower Heating Value (LHV) which is adjusted by adding the heat of vaporization of water, and heat required to raise the temperature of reactants to the combustion temperat...A better estimate may be the Lower Heating Value (LHV) which is adjusted by adding the heat of vaporization of water, and heat required to raise the temperature of reactants to the combustion temperature and products to 150 o C (an arbitrarily chosen standard). This is still different from the LHV because of the heat required to change the temperature of the reactants and products from the standard temperature (25 o C) to the combustion temperature.
