A study on the interchangeability of LFG–LPG mixed fuels with LFG quality in domestic combustion appliances

The interchangeabilities of LFG–LPG mixed fuels with respect to application in domestic combustion appliances were investigated. Two kinds of mixed fuels (MF(WI) and MF(HV)) were produced so as to have a Wobbe index (WI) and a heating value (HV) nearly equivalent to those of LNG, respectively. In this study, the qualities of LFG used in making mixed fuels were considered by varying CH4 volume fraction in the LFG composition from 55% to 30%. The fundamental characteristics were estimated through comparisons of flame temperature, burning velocity, and the stability region of various fuels. It was found that All MF(WI)s have very similar stable flame zones regardless of the LFG quality, and these mixed fuels can substitute CH4 completely without any modification of the air entrainment device. On the other hand, the stable flame zone of MF(HV) is decreased to a lower fuel flowrate with a decrease of CH4 percentage in LFG. These fuels can substitute CH4 with some restrictions and the air inlet device must be adjusted to lower the air flowrate entrained by the fuel jet.