The eddy dissipation concept (EDC) model has the ability to incorporate detailed chemistry in turbulent combustion, which makes it attractive for simulating a wide range of industrial combustion systems. However, its application for modeling weakly turbulent reacting flows and slow chemistry poses a real challenge. The present study examines the influence of the EDC model’s coefficients, with respect to turbulent flow field characteristics. In order to assess the sensitivity of EDC model’s constants, simulations of two distinct jet flames covering weakly and highly turbulent flow conditions are performed. The predictions are compared with published experimental measurements. The findings of this study revealed that EDC predictions of the characteristics of weakly turbulent reacting flow can be improved by changing the model’s constants. The study also showed that, in comparison with the standard EDC, modifying the model’s coefficients produced improved predictions of the characteristics of highly turbulent reacting flow regions. The conclusions of the analysis carried out in this study are used to simulate the gas-phase combustion of a small-scale biomass furnace using the EDC model, which is presented in the companion paper for this study.

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Small-scale grate-firing biomass furnaces suffer from high levels of pollutant emissions caused mainly by a low level of air/fuel mixing and a short residence time for combustion as a result of their small volume. Reliable gas-phase combustion modeling is key for improving the design of these systems. The present work describes a computational fluid dynamics study of biomass combustion using the modified eddy dissipation concept (EDC) model. Part 1 (10.1021/acs.energyfuels.6b01947) of this study focused on examining the main challenges of the EDC model regarding its application for modeling weakly turbulent and slow-chemistry reacting flows. In addition, a sensitivity analysis was carried out on the constants of the model for modeling non-premixed combustion at weakly and highly turbulent reacting flow conditions. Using the conclusions of the analysis of part 1 (10.1021/acs.energyfuels.6b01947), gas-phase combustion of a small lab-scale grate-firing biomass furnace is simulated in the present paper (part 2). The results revealed that the modified EDC model produced reasonable predictions of the temperature and gas emissions.

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