文献类型：期刊文献

英文题名：Explosion characteristics of argon/nitrogen diluted natural gas-air mixtures

作者：Zhang, Bo[1,2];Xiu, Guangli[1];Bai, Chunhua[2]

机构：[1]E China Univ Sci & Technol, State Environm Protect Key Lab Environm Risk Asse, Shanghai 200237, Peoples R China;[2]Beijing Inst Technol, State Key Lab Explos Sci & Technol, Beijing 100081, Peoples R China

年份：2014

卷号：124

起止页码：125

外文期刊名：FUEL

收录：;EI(收录号：20141017416410);WOS:【SCI-EXPANDED(收录号:WOS:000332403600016)】；

基金：This work is supported by the Fundamental Research Funds for the Central Universities (Grant No. 222201314030), Shanghai Post-doctoral Sustentation Fund, China (Grant No. 13R21411800), and the project of State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology (Grant No. KFJJ15-03M).

语种：英文

外文关键词：Natural gas; Flammability limits; Maximum explosion pressure; Maximum rate of pressure rise; Laminar burning velocity

摘要：This work was initiated to address safety concerns related to natural gas (NG)-air mixtures. NG, being an alternative fuel for vehicles and a chemical feedstock in the manufacture of organic chemicals, has been widely used in the industrial process in the past decade. NG is a flammable, gaseous fuel and thus presents a fire and explosion hazard. In this study, an investigation of the explosion characteristics including flammability limits, maximum explosion pressure (p(max)), maximum rate of pressure rise (dp/dt)(max), and laminar burning velocity (S-L) is carried out by systematically measuring the pressure histories in a standard 20-L spherical vessel. The dilution effects on the explosion characteristics are also explored through the addition of two diluents, i.e., argon (Ar) and nitrogen (N-2), into the NG-air mixture. The experimental results indicate that the flammability region ranges from 5.5% to 15% NG by volume at ambient conditions. It is found that reducing the initial pressure decreases the interval width of flammability limits. This is due to the distance between the molecules of the gas being shorter as the initial pressure increases and therefore, resulting in a higher probability of effective collision between molecules. Consequently, this effect in turn promotes the initial and subsequent chemical reactions. The results also show that increasing diluent ratio results in a narrower flammability region and that the effect of N-2 addition is more pronounced than Ar. The present results also confirm that the variation of pmax with the equivalence ratio of NG exhibits an inversely "U-shaped" behavior and p(max) decreases with decreasing initial pressure. In general, the addition of Ar and N-2 would decrease the value of p(max). However, it is observed in this study that the value of p(max) fluctuates when argon is added, especially for those mixtures with phi < 1. It is noted that increasing Ar dilution returns the mixture to an ignition condition and even reaches an optimal composition (i.e., close to the stoichiometric condition). On the other hand, the Ar dilution has a suppression effect on the explosion. These two competing effects with increasing Ar dilution therefore make p(max) remain relatively constant within an interval of dilution percentage for fuel lean mixtures (e. g., with fuel concentration C-NG equal to 5% and 6%). Finally, results also indicate that S-L decreases with an increase of initial pressure and the rate of decrease of S-L is faster when the mixture is diluted with N-2 compared to the effect of Ar. This can be explained by the fact that the density dominates over the retarding effect for S-L. (C) 2014 Elsevier Ltd. All rights reserved.