The abbreviation for High Heating Value. The amount of heat produced by the complete combustion of a unit quantity of fuel. The gross heating value is obtained when all products of the combustion are cooled down to the temperature before the combustion and the water vapor formed during combustion is condensed.
Common units used for heating value are:
1 Btu/lb = 2326.1 J/kg = 0.55556 kcal/kg
1 J/kg = 0.00043 Btu/lb = 2.39 × 10-4 kcal/kg
1 kcal/kg = 1.80 Btu/lb = 4187 J/kg