Abstract
Exergy destructions in laminar premixed syngas flames, with varied fuel compositions and changed pressures, were numerically studied. Chemical reactions are found to be the dominant source for exergy destruction, followed by heat conduction and mass diffusion. As a result of the trade-off between the increased exergy destruction rates and narrowed flame thickness, the total exergy destruction increases by about 1% with hydrogen enrichment, but is nearly unchanged with pressure elevation. Specifically, with hydrogen enrichment, the exergy destruction from heat conduction decreases due to the narrowed flame thickness, whereas those from mass diffusion and chemical reactions increase because of higher diffusivity of H2, H and H2O and higher reactivity of H2 than CO, respectively. In contrast, with pressure elevation, the higher temperature gradient and mole fraction gradients result in increased exergy destruction from heat conduction, but the exergy destruction from chemical reactions decrease due to the narrowed flame thickness.
Published Version
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