Wobbe Index for Gaseous Fuels

In the particular case of gaseous fuels when, for technical or economical reasons, it is necessary to replace one gas by another using the same burner piping and control, several parameters, such as the heat content, burner stability, and oxidant, must remain unchanged to ensure safe interchangeability. The Wobbe index (WI) expressed in MJ.m is used especially to evaluate the interchangeability of two gaseous fuels with respect to mass and heat flow rate. It is defined as follows  

When both the original and substitute fuels have the same Wobbe index no major change in gas handling equipment and piping is necessary. 

Finally, combustion calculations regarding common hydrocarbons and other organic fuels require accurate experimental data. Therefore, the usual data required for these computations are reported in Table 17.3. 

References Cox, J.D. Wagman, D.D. Medvedev, V.A. (1984) CODATA Key Values for Thermodynamics. Hemisphere Publishing Corp., New York, 1984 Chase, M.W., Jr. (1998) NIST-JANAF Themochemical Tables, 4th.ed. J. Phys. Chem. Ref. Data, Monograph 9, Springer, New York. 

Having described the main physical quantities related to the combustion of fuels, the description of the most important groups of fuels is presented in the following paragraphs. 

---