Experimental Study of Lean-burning Limits of Hydrogen-enriched LPG Intended for Domestic Use

The lean-burning limits of hydrogen-enriched Liquefied Petroleum Gas (LPG) have been studied using a Bunsen burner. The lean-burning limits under different conditions are important design considerations in developing gas-fired domestic appliances. In this study, the lean-burning limits of hydrogen-enriched LPG have been obtained across a wide range of Reynolds numbers (600 to 1800) and H2 volumetric fractions (0% to 25%). The results show that the lean-burning limit is increased, on average, by 4.0% to 7.2% for every 5% increment of H2 volumetric fraction under different Reynolds numbers. A numerical simulation carried out in CHEMKIN using the USC Mech II reaction mechanism, and the observation of flame characteristics show that the increase in lean-burning limit with increasing H2 content is due to the higher burning velocity of LPG-H2 mixtures compared with pure LPG. More fuel is required to offset the effect of increased burning velocity under the same Reynolds number, leading to an increase in the lean-burning limit. To facilitate the visualization of the variation of the lean-burning limit with increasing H2 volume fraction in the mixed fuel at different Reynolds numbers, a lean-burning limit map is developed based on correlations obtained. The results of this study provide reference values for the lean-burning performance of hydrogen-enriched LPG fuel for practical domestic use.