Heating Value of a Gas

The Heating Value of a Gas:

✔ The heating value of a gas is defined as the thermal energy per unit volume of the gas. 
✔ It is expressed in Btu/ft³
✔ For natural gas, it is approximately in the range of 900 to 1200 Btu/ft³
✔ There are two heating values used in the industry. These are the lower heating value (LHV) and higher heating value (HHV). 
✔ For a gas mixture, the term gross heating value is used. 
✔ It is calculated based upon the heating values of the component gases and their mole fractions using the following equation:

H_m = Σ(y_iH_i)

Where,

          H_m = Gross heating value of Mixture, Btu/ft³
          y_i  = Mole fraction or percent of gas component, i
          H_i = Heating Value of gas component, Btu/ft³