Abstract
The consequences of H2 enrichment on the laminar burning velocity (LBV) of various liquefied petroleum gas (LPG) blends have been studied experimentally and numerically. The study was carried out at various equivalence ratios (ϕ) (from 0.8 to 1.3 in steps of 0.1). Experiments were conducted on various LPG blends, by adding hydrogen up to 60% by volume in steps of 20, using the heat flux method (HFM) experimental setup. A detailed computational study was conducted using a PREMIX code to predict the LBV and to explain the flame structure of LPG–hydrogen–air mixtures. LBV predictions using two different chemical kinetic mechanisms such as Aramco Mech 2.0 and USC Mech II mechanism were compared with experimental results of the LBV for all the fuel mixture compositions studied. The LBV predicted by the Aramco Mech 2.0 mechanism matched well with the present experimental results. The LBV of the LPG–air mixture was observed to be increasing upon hydrogen addition. A linear increase in the LBV upon hydrogen addition was observed until 40% H2 addition in the fuel mixture. The effect of hydrogen addition was found to be more significant at 60% H2, showing a nonlinear increase in the LBV from 40 to 60% H2 addition. The effect of hydrogen addition on the LBV was observed to be prominent in the rich mixture side. The variation in the LBV with hydrogen enrichment was found to be dependent on the concentration of C3H8 in the fuel mixture. The effect of the composition of propane and butane on the LBV of LPG was also studied. The laminar burning velocity at elevated temperatures was measured using a diverging channel setup for LPG (60% C4H10–40% C3H8) at various H2 compositions. The temperature exponent was found to be decreasing with the hydrogen addition. The minimum value of the temperature exponent for all the studied mixture compositions was observed at ϕ = 1.1.