Experimental study of a laminar premixed LFG/air flame in a slot burner using Mach-Zehnder interferometry

Abstract

An experimental study was conducted to investigate the influence of Reynolds number and equivalence ratio on flame temperature field and thermal flame height of laminar premixed landfill gas fuel. Mach-Zehnder interferometry technique is used to obtain an insight to the overall temperature field. The slot burner with large aspect ratio, length of 60 mm and width of 6 mm, was used to eliminate the three-dimensional effect of temperature field. Two kinds of mixed fuels, LFG 70 (70% CH 4-30% CO 2 on volume basis) and LFG 50 (50% CH 4-50% CO 2) were used to investigate flame characteristics under the test conditions of 100 ≤ Re ≤ 600 and 0.7 ≤ φ ≤ 1.3. The present measurement reveals that the variation of maximum flame temperature with increment of Reynolds number is mainly due to heat transfer effects and is negligible. On the other hand, the equivalence ratio and fuel composition have a noticeable effect on flame temperature. In addition, the results show that the landfill gas flames compared to the CH 4 ones have a lower flame temperature. With increment of CO 2 volume fraction at lean combustion, thermal flame height is augmented while at stoichiometric and rich combustion, its value reduced. Thermal flame height augments linearly by Reynolds number increase, while its increment at rich mixture is higher and the effect of Reynolds number at lean mixtures is insignificant. For validation of experimental results from Mach-Zehnder Interferometry, K-type thermocouples are used at peripherally low and moderate isotherm lines.