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Abstract :
In the operation of the entrained-flow gasifier, it is necessary to seek the optimal coal blending plan to regulate the melting and flow characteristics of coal ash. The SiO2-Al2O3-AAEM(CaO+MgO+Na2O+K2O) pseudo-ternary isotherm was used to analyze the melting characteristics of Ningdong coal ash with different compositions, and combined with X-ray diffraction (XRD) to explore the mineral transformation law of ash in the melting process. It is found that the melting temperature presents a U-shaped distribution in the pseudo-ternary isotherm; when the mass fractions of SiO2, Al2O3 and AAEM are 37.5%,25.0%and 37.5%, respectively, the melting temperature of coal ash is the lowest, and the flowing temperature is 40 lower than that of Ningdong coal ash. The analysis of mineral transformation during ash melting indicates that the mineral transformation reaction between quartz and calcium oxide in the process of melting can finally produce feldspar and gehlenite with low melting point, significantly promoting ash melting. The analysis of the viscosity-temperature characteristic curves of liquid molten slags generated after ash melting indicates that ash samples at this ratio has the lowest critical viscosity-temperature (TCV=1107 ) and the lowest activation energy of viscous flow (Ea=282.86 kJ/mol), which can effectively reduce the operating temperature of gasifiers. The study shows that the pseudo-ternary isotherm can guide the preparation of coal blending plans for feedstock gasification. © 2023 Science Press. All rights reserved.
Keyword :
Activation analysis Activation energy Alumina Aluminum oxide Blending Coal Coal ash Feldspar Lime Magnesia Melting point Silica Slags Sodium compounds Viscosity
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GB/T 7714 | Kan, Haoyong , Li, Ping , Chen, Cai et al. Study on Melting and Flowing Characteristics of Ningdong Coal Ash at High Temperatures Based on Pseudo-ternary Isotherm Diagrams [J]. | Acta Petrolei Sinica (Petroleum Processing Section) , 2023 , 39 (1) : 134-141 . |
MLA | Kan, Haoyong et al. "Study on Melting and Flowing Characteristics of Ningdong Coal Ash at High Temperatures Based on Pseudo-ternary Isotherm Diagrams" . | Acta Petrolei Sinica (Petroleum Processing Section) 39 . 1 (2023) : 134-141 . |
APA | Kan, Haoyong , Li, Ping , Chen, Cai , Niu, Yanqing . Study on Melting and Flowing Characteristics of Ningdong Coal Ash at High Temperatures Based on Pseudo-ternary Isotherm Diagrams . | Acta Petrolei Sinica (Petroleum Processing Section) , 2023 , 39 (1) , 134-141 . |
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Abstract :
To understand the influence of hydrogen addition on the auto-ignition characteristics of ammonia fuel, the experimental, simulation and theoretical studies on the ignition delay times of ammonia/hydrogen mixtures were carried out. The ignition delay times of stoichiometric ammonia/ hydrogen mixtures were measured in a shock tube at 1 MPa, 1124∼1695 K, and 0%, 5%, 30% and 70% hydrogen blending ratio. Based on the experimental data, the prediction performances of existing ammonia kinetic models on ignition delay times were evaluated, the chemical kinetic interaction of ammonia/hydrogen ignition was analyzed by using the Otomo model. It is found that the ignition delay of ammonia decreases nonlinearly with the increase of hydrogen blending ratio; the chemical equilibrium of NH3 + H ⇔ NH2 + H2 can be reversed by 5% hydrogen doping; with the increase of hydrogen mixing ratio, the inhibition effect of ammonia -related reaction on ignition is enhanced, and the promotion effect of hydrogen addition on the ignition delay time is weakened. © 2023, Science Press. All right reserved.
Keyword :
Ammonia Blending Hydrogen Ignition Kinetics Shock tubes
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GB/T 7714 | Chen, Jundie , Jiang, Xue , Zhang, Rui et al. Experimental and Chemical Kinetic Study on High Temperature Auto-Ignition Characteristics of Ammonia/Hydrogen [J]. | Journal of Engineering Thermophysics , 2023 , 44 (1) : 250-256 . |
MLA | Chen, Jundie et al. "Experimental and Chemical Kinetic Study on High Temperature Auto-Ignition Characteristics of Ammonia/Hydrogen" . | Journal of Engineering Thermophysics 44 . 1 (2023) : 250-256 . |
APA | Chen, Jundie , Jiang, Xue , Zhang, Rui , Qin, Xiaokang , Huang, Zuohua . Experimental and Chemical Kinetic Study on High Temperature Auto-Ignition Characteristics of Ammonia/Hydrogen . | Journal of Engineering Thermophysics , 2023 , 44 (1) , 250-256 . |
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Rapidly growth of organic solid waste (OSW) has caused serious social and environmental problems. Incineration as one of the most good public acceptance and environmentally friendly method attains increasing attention. In this study, the co-combustion characteristics of OSW and lignite, including the ignition and burnout temperature, ash melting and slagging propensity were studied. The experimental results show that the ignition temperature almost remains stable while the burnout temperature of the blends decreases as the increase of the OSW blending ratio, since the heat release during volatile combustion is beneficial for the burnout of coal char, but the polymer may melt and block the pores of the coal char at high temperature when the OSW blending ratio is higher than 30%. Besides, the slagging propensity of blending fuel is severe when the OSW blending ratio is 30%, and special attention should be paid to avoid slagging during the combustion process. © 2022 Energy Institute
Keyword :
Blending Coal combustion Ignition Lignite Polymer blends Waste incineration
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GB/T 7714 | Liu, Hu , Wang, Yancheng , Xue, Jingwen et al. Experimental study on combustion, ash fusibility and slagging propensity during co-combustion of organic solid waste and lignite [J]. | Journal of the Energy Institute , 2023 , 106 . |
MLA | Liu, Hu et al. "Experimental study on combustion, ash fusibility and slagging propensity during co-combustion of organic solid waste and lignite" . | Journal of the Energy Institute 106 (2023) . |
APA | Liu, Hu , Wang, Yancheng , Xue, Jingwen , Zhang, Yankang , Yu, Pengfei , Che, Defu . Experimental study on combustion, ash fusibility and slagging propensity during co-combustion of organic solid waste and lignite . | Journal of the Energy Institute , 2023 , 106 . |
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The oxy-fuel combustion allows the large-scale CO2 capture from coal-fired power plant, which is an effective approach to reduce CO2 emission and achieve carbon neutrality. The ultra-low volatile carbon-based fuels (LVFs, mainly including gasification residual carbon and pyrolyzed semi-coke) generated from the coal chemical industry cannot be directly disposed effectively, but co-firing with other fuels (bituminous coal for example) is a potential option. However, many nitrogen oxides (NOx) are possibly generated with the absence of combustion stability. Here, the present study aimed at co-combusting LVFs with bituminous coal under oxy-fuel condition to take advantages of oxy-fuel technology to deeply reduce NOx and realize large-scale CO2 capture. The effects of atmosphere and fuel property on co-combustion performances were numerically investigated. The simulation results of co-combustion demonstrate that the NOx emission increases as the mass fraction of bituminous coal falls. The effects of oxidizing gas distribution method on the co-combustion characteristics are highly related to the properties of co-firing fuels. The premixed combustion for bituminous coal/semi-coke co-combustion and in-furnace blending (residual carbon injected from the E layer) for bituminous coal/residual carbon co-combustion could yield less NOx. It is recommended that the oxy-fuel O2 concentration could be kept between 27% and 30% considering the balance between NOx generation and combustion behavior. The 50% bituminous coal/50% semi-coke co-combustion is applicable to co-fire using premixed combustion and appropriate reduction of secondary oxidizing gas flow in the semi-coke layers. The present research will contribute to a further understanding of the efficient and environmentally-friendly utilization of LVFs, as well as better knowledge of CO2 capture and carbon neutrality during electricity generation. © 2022 Elsevier Ltd
Keyword :
Bituminous coal Blending Carbon dioxide Chemical industry Coal combustion Coal fired power plant Coal industry Flow of gases Fossil fuel power plants Nitrogen oxides
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GB/T 7714 | Wang, Chang'an , Hou, Yujie , Feng, Qinqin et al. Numerical simulation on co-firing ultra-low volatile carbon-based fuels with bituminous coal under oxy-fuel condition [J]. | Fuel , 2023 , 332 . |
MLA | Wang, Chang'an et al. "Numerical simulation on co-firing ultra-low volatile carbon-based fuels with bituminous coal under oxy-fuel condition" . | Fuel 332 (2023) . |
APA | Wang, Chang'an , Hou, Yujie , Feng, Qinqin , Wang, Chaowei , Gao, Xinyue , Che, Defu . Numerical simulation on co-firing ultra-low volatile carbon-based fuels with bituminous coal under oxy-fuel condition . | Fuel , 2023 , 332 . |
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Abstract :
Hydrogen blending in natural gas is an effective way of carbon reduction. The effect of hydrogen blending on the reaction pathway of NOx emission from natural gas combustion in industrial furnaces is studied by chemical kinetic calculations. To ensure the reliability of kinetic calculation, the NOx prediction accuracy of the mechanisms GRI and PG2018 were compared by validation with corresponding experiments. It is found that the PG2018 mechanism is more accurate for NOx prediction than GRI 2.11 and GRI 3.0, especially for N2O-intermediate and NNH pathways. The effect of hydrogen blending on the chemical pathways of NOx production was obtained based on PSR reactor and burner stabilized laminar flame with a well-controlled temperature profile. The results show that in the PSR reactor, N2O-intermediate and thermal NOx are predominating pathways for NOx formation. NOx emissions of unit fuel heating value first rise with the increase of blending ratio and then reduces rapidly while the blending ratio is greater than 50%, which is mainly due to the suppression of thermal NOx and the increase of N2O-intermediate NOx. It can be found from calculation results of burner stabilized flame that the prompt NOx decreases dramatically in the laminar flame and the NOx production via NNH increases slightly as hydrogen blending ratio increases. With increasing hydrogen blending ratio, thermal NOx is suppressed, and the N2O-intermediate pathway is suppressed also at the flame sheet but enhanced in the flue gas due to the increment of the H2O content. NOx emission decreases with increasing hydrogen blending ratio in laminar flame at a given combustion temperature. © 2022 Hydrogen Energy Publications LLC
Keyword :
Blending Combustion Gases Industrial emissions Kinetics Natural gas Nitrogen oxides
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GB/T 7714 | Pan, Hejitian , Geng, Sajie , Yang, Huan et al. Influence of H2 blending on NOx production in natural gas combustion: Mechanism comparison and reaction routes [J]. | International Journal of Hydrogen Energy , 2023 , 48 (2) : 784-797 . |
MLA | Pan, Hejitian et al. "Influence of H2 blending on NOx production in natural gas combustion: Mechanism comparison and reaction routes" . | International Journal of Hydrogen Energy 48 . 2 (2023) : 784-797 . |
APA | Pan, Hejitian , Geng, Sajie , Yang, Huan , Zhang, Guohong , Bian, Hao , Liu, Yinhe . Influence of H2 blending on NOx production in natural gas combustion: Mechanism comparison and reaction routes . | International Journal of Hydrogen Energy , 2023 , 48 (2) , 784-797 . |
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Abstract :
Due to the high content of volatile nitrogen in sewage sludge, co-combustion of coal and sewage sludge easily leads to high emission of nitric oxides (NOx). To solve this problem, we applied the high-temperature preheating technology to promote the advance conversion of fuel-nitrogen into N2 so as to reduce NOx emission. In this study, a two-stage drop-tube furnace system was employed. The effects of sludge proportion, excess air ratio in the preheating zone (λ1), preheating temperature, and combustion temperature on NO emission and burnout were investigated. Our results showed that with the preheating treatment, increasing the sludge proportion reduced NOx emission and promoted char burnout. NO emission was the lowest when λ1 increased to 0.5. Under this condition, 62% of the fuel nitrogen could be converted to the gaseous species, in which the portion of N2 was 89.7%. By controlling λ1 to 0.5 and sludge proportion to 15%, the maximum NO reduction of 62% was achieved. The emitted NO and unburnt carbon in fly ash were reduced by 48.3% and 43.2%, respectively, when the preheating temperature increased to 1200 °C. The effect of combustion temperature strongly depended on the stoichiometry ratio. In oxygen-deficient regions, NO emission decreased with the increase of temperature, while an opposite trend appeared in oxygen-rich regions. The critical excess air ratio in our experiments was around 0.8. © 2022 Elsevier Ltd
Keyword :
Blending Coal combustion Fly ash Nitric oxide Nitrogen Nitrogen oxides Oxygen Preheating Sewage sludge Waste incineration
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GB/T 7714 | Lv, Zhaomin , Xiong, Xiaohe , Ruan, Renhui et al. NO emission and burnout characteristics in co-combustion of coal and sewage sludge following high-temperature preheating [J]. | Fuel , 2023 , 331 . |
MLA | Lv, Zhaomin et al. "NO emission and burnout characteristics in co-combustion of coal and sewage sludge following high-temperature preheating" . | Fuel 331 (2023) . |
APA | Lv, Zhaomin , Xiong, Xiaohe , Ruan, Renhui , Wang, Yibin , Tan, Houzhang . NO emission and burnout characteristics in co-combustion of coal and sewage sludge following high-temperature preheating . | Fuel , 2023 , 331 . |
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Abstract :
The co-gasification of coal and biomass through fluidized bed gasifier is a promising technology for the improvement of the utilization efficiency of fossil fuels and the development of renewable energy. In this work, a coarse-grained computational fluid dynamics-discrete element method (CFD-DEM) simulation is performed to investigate the co-gasification process in a bubbling fluidized bed gasifier. The effects of particle size distribution and operating pressure on the hydrodynamics, heat transfer, and co-gasification performance are analyzed. The results show that the increase of sand particle size distribution (PSD) width slightly affects the particle concentration distribution, particle residence time distribution, and co-gasification performance. The heat transfer rate of convection is an order of magnitude higher than those of conduction and radiation. At higher PSD width, the formation of the vertical solid temperature gradient at the bed bottom is attributed to the deteriorated solid mixing. As the operating pressure increases, the bed temperature decreases apparently. In addition, the variation of the convective heat transfer rate dominates the heat transfer efficiency as the operating pressure changes. The application of elevated operating pressure benefits to the thermal-chemical conversion of blend fuel since the char conversion reaction is accelerated. © 2022 Elsevier Ltd
Keyword :
Blending Chemical reactors Computational fluid dynamics Fluid catalytic cracking Fluidized bed furnaces Fluidized beds Fossil fuels Heat convection Light transmission Particle size Particle size analysis Residence time distribution Size distribution Supersaturation
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GB/T 7714 | Du, Shaohua , Wang, Jiahao , Yu, Yaxiong et al. Coarse-grained CFD-DEM simulation of coal and biomass co-gasification process in a fluidized bed reactor: Effects of particle size distribution and operating pressure [J]. | Renewable Energy , 2023 , 202 : 483-498 . |
MLA | Du, Shaohua et al. "Coarse-grained CFD-DEM simulation of coal and biomass co-gasification process in a fluidized bed reactor: Effects of particle size distribution and operating pressure" . | Renewable Energy 202 (2023) : 483-498 . |
APA | Du, Shaohua , Wang, Jiahao , Yu, Yaxiong , Zhou, Qiang . Coarse-grained CFD-DEM simulation of coal and biomass co-gasification process in a fluidized bed reactor: Effects of particle size distribution and operating pressure . | Renewable Energy , 2023 , 202 , 483-498 . |
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Abstract :
Ammonia is identified as a promising fuel, because of the advantages of its carbon-free nature and well-established carriage and storage technique. However, NH3 fuel is still facing several challenges which mainly include the difficulties to stabilize flames and the unacceptable huge NOx emissions. In this study, the reacting flow fields and the flame structures of NH3/air flames as well as NH3/CH4/air flames on low CH4 blending ratio were measured. The turbulence intensity of two kinds of flames shows difference at the flame positions. The turbulence intensity of 90%NH3 flame is higher than that of NH3 flame. At the same bulk velocity, the effect of equivalence ratio on the NH3 flame structure is mainly concentrated on the change of the flame height. A gas analyzer was used to measure the emissions. The addition of CH4 increases the unburned NH3 emission during equivalent ratio over 1.0, and also causes large CO and CO2 emissions. The NOx emissions of 90%NH3 flame is higher than that of NH3 flame. At the condition near equivalent ratio of 1.1, all emissions are relatively low, and the low methane blending ratio does not have a significant impact on this low emission position. © 2022, Science Press. All right reserved.
Keyword :
Ammonia Blending Combustion Fuel storage Gas emissions Methane Nitrogen oxides Turbulence
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GB/T 7714 | Wei, Xu-Tao , Wang, Jin-Hua , Zhang, Meng et al. Investigation on Flame Structure and NOx Emissions of Ammonia/methane/air Swirl Stabilized Flames [J]. | Journal of Engineering Thermophysics , 2022 , 43 (4) : 1108-1115 . |
MLA | Wei, Xu-Tao et al. "Investigation on Flame Structure and NOx Emissions of Ammonia/methane/air Swirl Stabilized Flames" . | Journal of Engineering Thermophysics 43 . 4 (2022) : 1108-1115 . |
APA | Wei, Xu-Tao , Wang, Jin-Hua , Zhang, Meng , Su, Li-Tian , An, Zhen-Hua , Huang, Zuo-Hua et al. Investigation on Flame Structure and NOx Emissions of Ammonia/methane/air Swirl Stabilized Flames . | Journal of Engineering Thermophysics , 2022 , 43 (4) , 1108-1115 . |
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Abstract :
To fill the gaps in domestic research on the hypergolicity of low vapor pressure fuels and nitrous oxide (NTO), the hypergolic characteristics of low vapor pressure fuels in NTO were studied using the dripping experimental device. The four low vapor pressure fuels selected in this paper are 1-ethyl-3-methylimidazolium thiocyanate, 1-butyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium dicyano amine and 1-methyl-imidazolborane. At the same time, the smoke delay time of low vapor pressure fuels and the ignition delay time of 1-methyl-imidazolborane blended with ethylene glycol and propylene glycol were analyzed. The results show that none of the three imidazole-based ionic liquids could spontaneously ignite with NTO, but 1-methyl-imidazolborane could spontaneously ignite with NTO. The hypergolic process is as follows: Droplets and NTO contact and mix; black smoke appears; flame appears. Among the four low vapor pressure fuels, 1-methyl-imidazolborane has the shortest smoke delay time. When the cations are the same, the smoke delay time for the anion being thiocyanate is less than that of dicyanamide. When the anions are the same, the longer the carbon chain is contained in the cation, the shorter the smoke delay time will be. The ignition delay time of the blended fuel is greater than that of 1-methyl-imidazolborane, and its ignition delay time first decreases and then increases with the increase of the molar ratio of additives. When the blending ratios of ethylene glycol and propylene glycol are greater than 0.4 and 0.5, respectively, it is difficult for the blended fuel to ignite spontaneously with NTO. When the molar ratio of ethylene glycol and propylene glycol added to 1-methyl-imidazolborane is the same, the ignition delay time of the former is shorter than that of the latter, indicating that the self-ignition effect of 1-methyl-imidazolborane added with ethylene glycol is better than that of 1-methyl-imidazolborane added with propylene glycol. © 2022, Editorial Board of Journal of Xi'an Jiaotong University. All right reserved.
Keyword :
Additives Blending Ethylene Ethylene glycol Hydrostatic pressure Ionic liquids Negative ions Nitrogen oxides Polyols Positive ions Propylene Smoke
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GB/T 7714 | Li, Yutong , Wang, Mei , Tan, Ziyang et al. Study on Hypergolic Characteristics of Low Vapor Pressure Fuels and Nitrous Oxide [J]. | Journal of Xi'an Jiaotong University , 2022 , 56 (6) : 34-39 . |
MLA | Li, Yutong et al. "Study on Hypergolic Characteristics of Low Vapor Pressure Fuels and Nitrous Oxide" . | Journal of Xi'an Jiaotong University 56 . 6 (2022) : 34-39 . |
APA | Li, Yutong , Wang, Mei , Tan, Ziyang , Pang, Yingran , Li, Yaxin , Gao, Zhongquan et al. Study on Hypergolic Characteristics of Low Vapor Pressure Fuels and Nitrous Oxide . | Journal of Xi'an Jiaotong University , 2022 , 56 (6) , 34-39 . |
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Abstract :
To fill the gaps in domestic research on the hypergolicity of ionic liquids and green oxidants, this paper studies hypergolic characteristics of imidazole thiocyanate ionic liquids in 90% hydrogen peroxide and analyzes the impact of droplet collision speed and different additives on the ignition delay time (IDT) of such liquids in hydrogen peroxide. The results show that the hypergolic process of such liquid in hydrogen peroxide is divided into three stages:liquid pits appear when droplet contacts and mixes with hydrogen peroxide; the central jet appears and the droplet separates from the top of the jet; the temperature rises, black smoke and fire cores appear. The IDT of the ionic liquid has a negative correlation with the collision speed. Due to the influence of factors such as viscosity and combustion limit, the reduction of IDT of 1-ethyl-3-methylimidazole thiocyanate ([EMIM][SCN]) decreases with the increase of collision speed, while 1-Butyl-3-methylimidazole thiocyanate ([BMIM][SCN]) is the opposite. At the same collision speed, the IDT of [BMIM][SCN] is shorter than [EMIM][SCN], indicating that[BMIM][SCN] has a good hypergolic ignition effect with 90% hydrogen peroxide. The IDT of the blended fuel increases with the increase of the molar ratio of the additives and is greater than the IDT of the ionic liquid. When [EMIM][SCN] was blended with ethylene glycol with a molar ratio of 0.8, [BMIM][SCN] was blended with ethylene glycol with a molar ratio of 0.9, and [EMIM][SCN] and [BMIM][SCN] blended with propylene glycol with a molar ratio of 0.7, it is difficult for hypergolic ignition at different collision speeds This indicates combustion performance of imidazole thiocyanate ionic liquid in 90% hydrogen peroxide cannot be improved by blending ethylene glycol or propylene glycol. © 2022, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.
Keyword :
Blending Drops Ethylene Ethylene glycol Fuel additives Hydrogen peroxide Ignition Ionic liquids Molar ratio Oxidation Polyols Propylene Smoke
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GB/T 7714 | Li, Yutong , Pang, Yingran , Gao, Zhongquan et al. Study on the Hypergolic Characteristics of Imidazole Thiocyanate Ionic Liquids and Hydrogen Peroxide [J]. | Journal of Xi'an Jiaotong University , 2022 , 56 (5) : 12-20 . |
MLA | Li, Yutong et al. "Study on the Hypergolic Characteristics of Imidazole Thiocyanate Ionic Liquids and Hydrogen Peroxide" . | Journal of Xi'an Jiaotong University 56 . 5 (2022) : 12-20 . |
APA | Li, Yutong , Pang, Yingran , Gao, Zhongquan , Tan, Ziyang , Chen, Pengfei , Tan, Yonghua et al. Study on the Hypergolic Characteristics of Imidazole Thiocyanate Ionic Liquids and Hydrogen Peroxide . | Journal of Xi'an Jiaotong University , 2022 , 56 (5) , 12-20 . |
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