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Show Multivariate Study of the Effects of Geometric Design Parameters on Furnace Performance A. Chang and G.S. Samuelsen UCI Combustion Laboratory University of California, Irvine Irvine, C A 92697-3550 USA ABSTRACT In low-NOx burner designs, small changes in burner geometry can significantly increase, or reduce, N O x and C O emissions. Of interest is the optimal design for a given configuration. Rather than testing all possible burner configurations, a design of experiments (DoE) can be used to optimize the testing process by systematically varying the parameters. The statistics-based analysis of variance (ANOVA) can then be used to analyze the results to identify effects of parameters on the responses or interactions between parameters. In the present case, a specially designed (for parametric flexibility) practical burner was utilized The parameters and their ranges include: a) flame holder angle (30°, 90°); b) fuel injection hole diameter (0.1", 0.3"); c) fuel injection hole location (1.25", 4.25" from base of flame holder); and d) swirl angle (30°, 60°). Results show that C O concentrations and combustion efficiency are not affected by the hardware changes. However, N O x emissions are affected by an interaction between the fuel injection hole diameter and the swirl angle. In particular, in the present case, lower N O x emissions are achieved by either a combination of smaller fuel injection hole diameter and larger swirl angle or a combination of larger fuel injection hole diameter and smaller swirl angle. INTRODUCTION Oxides of nitrogen (NOx) formed during the combustion process have been seen as a major air pollution problem before the inception of E P A a little less than three decades ago. NOx, which includes nitric oxide (NO), nitrogen dioxide (NO2) and nitrous oxide (N2O) is an important pollutant family for several reasons. N O x is a primary contributor to ozone non-attainment, and it contributes to acid deposition, forest damage, and visibility problems. N O x from stationary combustion sources contributes significantly to total emissions, and regulation and control of these emissions can result in significant improvements to the environment (USEPA, 1995). Air quality degradation and intensifying health concerns serve to increase the stringency of the regulations. The 1990 Clean Air Act Amendments include major programs designed to affect ozone (O3) attainment through a reduction in the emissions of N O x . Because of its role in the formation of photochemical oxidants (e.g., ozone), N O x is targeted by 1 |
