PROCEEDINGS OF THE COMBUSTION INSTITUTE
·
2018
·Vol. 37
·期 1
·565-573
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IF 5.336
Xiaoyuan Zhang,Yuyang Li,Chuangchuang Cao,Jiabiao Zou,Yan Zhang,Wei Li,Tianyu Li,Jiuzhong Yang,Philippe Dagaut
The kinetics of propanal oxidation was studied in a jet-stirred reactor (JSR) at atmospheric pressure. The investigated temperature range is from 450 to 800 K at two different equivalence ratios (0.35 and 4.0). Thanks to the synchrotron vacuum ultraviolet photoionization mass spectrometry (SVUV-PIMS), critical intermediates were identified, including methylperoxy, methyl hydroperoxide , ethylperoxy, ethyl hydroperoxide, α-lactone, β-propiolactone and ketohydroperoxides. A kinetic model for propanal oxidation was also developed and validated against the present experimental results, as well as those available from the literature. Main chain-branching pathways under the investigated conditions were analyzed based on present experimental data and kinetic model . The O 2 addition reaction to the propanoyl radical and subsequent oxidation reactions play an important role in determining the oxidation rate of propanal under fuel-lean conditions, especially in the low-temperature oxidation region. Under fuel-rich conditions, the decomposition of the propanoyl radical is predominant and C 2 H 5 relevant reactions consequently determine the kinetics of oxidation of propanal.
研究领域:
物理化学
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燃烧化学
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反应动力学
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分析化学
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能源化学
✓ 已验证
DOI
高影响因子
OCEAN & COASTAL MANAGEMENT
·
2016
·
IF 1.696
Dongmei Song,Lin Zang,Chunxiao Liu,Xuefa Shi,Huisheng Wu
The estuarine and coastal vulnerability around the world is increasing day by day, due to climate warming and sea level rise . And the resource-environmental pressure, caused by population expansion, also has been increasing. In a word, human interventions have caused lots of irreparable damages to the sensitive ecosystems in estuarine and coastal regions. Therefore, to carry out evaluations about ecological state and environmental bearing capacity is of great significance for environmental protection, as well as resource utilization. In this study, we constructed an indices system, which was based on a PSR model, to be used for the geologic bearing capacity assessment in coastal zones. There is no doubt that determination of indices weights is very important in the evaluation process, even it is a key factor restricting the ecological evaluation accuracy. Based on the above, we proposed a new weight determining method by fusing non-structural fuzzy number weighting and triangular fuzzy number weighting in the basis of the theories of fuzzy mathematics and named it as unstructured triangular fuzzy number weight determining method. In this new method, judgment matrix is used to calculate the relative importance among those indices included in the evaluation system with unstructured binary tone operators and rules of triangular fuzzy number. Therefore, this new method accords with the cognitive law of decision makers from macro to micro, and that three different experience attitudes (pessimistic, neutral, and optimistic) are fully considered can make the one-sidedness caused by a single attitude be avoided effectively. In addition, a new consistency test method entitled hierarchical sorting consistency test method was proposed to check the consistency of judgment matrix. This study took the coastal area around Laizhou Bay in Shandong Province of China for example and assessed the geologic bearing capacity here. The results indicate the geologic bearing capacity here is gradually increasing from the coast to the inland, and that the proposed weighting model is effective for eco-geological environment evaluation.
研究领域:
环境地质学
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海洋地理学
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生态学
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资源环境评价
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模糊数学应用
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海岸带管理
✓ 已验证
DOI
高影响因子
COMBUSTION AND FLAME
·
2021
·
IF 4.185
Jizhen Zhu,Sixu Wang,Mohsin Raza,Yuan Feng,Jing Li,Yebing Mao,Liang Yu,Yong Qian,Xingcai Lu
Methanol is an attractive oxygenate increasingly used as primary fuel for dual-fuel combustion technology yielding beneficial thermal-efficiency and emissions in modern engines. As such, it is significant to fundamentally understand the autoignition behavior of methanol/diesel mixtures. This study measured the ignition delay times (IDTs) of methanol/diesel blends with different mixing ratios (30%, 50%, 70% methanol by mol.) on a heated shock tube and a heated rapid compression machine at temperatures of 650−1450 K, pressures of 6−20 bar, and equivalence ratios of 0.5, 1.0 and 2.0. The typical two-stage ignition characteristics with the negative temperature coefficient response were observed for dual-fuel mixtures. In general, both the total and first-stage IDTs decrease with the increment of pressure and equivalence ratio as well as diesel proportion in mixtures. The simulation results performed with a published detailed mechanism in conjunction with a tri-component diesel surrogate demonstrate generally good agreement with the experimental data at all test conditions. Moreover, a crossover of IDTs occurs at a higher temperature (~1500 K) for varying equivalence ratios, and experiment and simulation both exhibit a non-linear mixing effect of methanol addition on diesel ignition. Interestingly, simulation results clearly suggest a crossover (~940 K) for mixtures with varying methanol content at an intermediate-temperature, where the IDT of the mixture with a lower methanol ratio becomes longer as the temperature is higher than that of the crossover. Furthermore, brute-force sensitivity analyses assisted with reaction path analysis were conducted to gain deeper insights into the autoignition chemistry of dual-fuel mixtures, especially for the chemical interaction between both fuels during the low-temperature oxidation process . It is found that methanol hardly generates •OH, whereas •OH is mainly produced by the low-temperature reaction pathways of diesel. Thus, •OH is the bridge for both fuels during the ignition process. At the high methanol ratio, the H-abstraction of diesel is mainly via •HO 2 while CH 3 OH consumes a large percentage of •OH. Consequently, the competition between methanol and diesel for •OH radicals inhibits the overall reactivity of reaction network. In addition, the original data reported here lay a foundation for the development and validation of more accurate and robust dual-fuel kinetic schemes.
研究领域:
燃烧化学
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燃料科学
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化学动力学
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内燃机工程
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替代燃料技术
✓ 已验证
DOI
高影响因子
THERMOCHIMICA ACTA
·
2016
·
IF 1.938
Lipeng Wang,Fucheng Zhang,Yongping Bai,Liping Ding
The kinetic of non-isothermal crystallization of Poly (ethylene terephthalate-co-sodium-5-sulfo- iso -phthalate) (PETI) was investigated using differential scanning calorimetry (DSC). Various macrokinetic models namely the Avrami, Tobin, Ozawa, and Ziabicki were used to describe the non-isothermal crystallization process of PETI. Both of the Avrami crystallization rate constant and the Tobin crystallization rate constant were observed to increase with increasing cooling rate. The Avrami model is better than the Tobin model to describe the non-isothermal crystallization process of PETI. The Ozawa crystallization rate K O was found to decrease with increasing cooling rate, while Ziabicki’s kinetic crystallizability parameter G Z was found to increase with increasing cooling rate. The effective energy barrier △E for non-isothermal crystallization process of PETI, analyzed based on the differential iso-conversional method of Friedman, was found to be an increasing function of the relative crystallinity.
研究领域:
高分子化学
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材料科学
·
物理化学
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热分析
·
聚合物结晶
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）