Effect of H2/CO Composition on Extinction Strain Rates of Counterflow Syngas Flames
详细信息 查看全文
- 作者：A. B. Sahu ; R. V. Ravikrishna
- 刊名：Energy & Fuels
- 出版年：2015
- 出版时间：July 16, 2015
- 年：2015
- 卷：29
- 期：7
- 页码：4586-4596
- 全文大小：662K
- ISSN：1520-5029
文摘
This work presents a detailed experimental and numerical investigation of the effect of H2/CO composition on extinction characteristics of premixed and nonpremixed syngas flames. Experimental measurements of local and global extinction strain rates in counterflow diffusion flames have been reported at atmospheric pressure for six different compositions of syngas fuel. The concentration of H2 was varied from 5 to 20% with a 3% increment, and correspondingly, CO was decreased from 35 to 20% in steps of 3%. Particle imaging velocimetry has been used to determine the local extinction strain rates. Local extinction strain rates increased with an increase in the H2/CO ratio in both nonpremixed and premixed flames. The predicted extinction strain rates for both nonpremixed and premixed counterflow flames using five different mechanisms available in the literature were compared with measurements. The Davis H2/CO and Ranzi H2/CO mechanisms predicted extinction strain rates within 10% of experimental values irrespective of the H2/CO ratio. In the nonpremixed case, the C1 mechanism by Li et al., GRI 3.0, and the Ranzi H2/CO mechanism predicted extinction strain rates well for low H2/CO ratios (from 5:35 to 14:26) but deviated from experiments for higher H2/CO values (17:23 and 20:20). In addition to kinetics, preferential diffusion effects were found to affect the reaction zone significantly and create distinct localized reaction zone structures in nonpremixed flames, which could contribute to discrepancies in extinction predictions.