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7th International Conference on power engineering, ICOPE 2019

作者： Feng, Qinqin Wang, Chang'an Lv, Qiang Zhao, Lin Du, Yongbo Wang, Pengqian Zhang, Jingwen Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China

Oxy-fuel combustion is clean and efficient combustion technology, which not only benefits the large-scale capture of CO2 but also reduces NOx emission, and then promotes the efficient and clean utilization of carbon-based solid fuels. This study mainly aimed at the oxy-fuel co-combustion of semi-coke and coal in utility boiler with special insight into NOx emission and combustion efficiency. The simulation results showed that when the blending ratio of semi-coke was 45%, the NOx concentration at the furnace outlet under oxy-fuel condition was increased with the oxygen content. The flue gas circulation modes ("dry" versus "wet") had insignificant impact on the NOx emission when the initial oxygen concentration was set as 24% and 27%. When the blending ratio of semi-coke was 70%, the differences of NOx emission between "dry" and "wet" flue gas circulation modes were enlarged with rise in oxygen content under oxy-fuel condition. For oxy-fuel cases, despite of the growth of burnout ratio, the carbon content in fly ash first increased and then decreased with the rise of oxygen content. With the oxygen concentration increased to 30%, lower carbon content in fly ash and higher burnout ratio could be observed in comparison to the cases under air condition. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Fly ash

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Laminar flame speeds of iso-octane/n-butanol blends-air mixtures at elevated temperatures

Laminar flame speeds of iso-octane/n-butanol blends-air mixt...

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9th Asia-Pacific Conference on Combustion, ASPACC 2013

作者： Zhang, Xinyi Yu, Huibin Tang, Chenglong Gong, Jing Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China

In this work, laminar flame speed of iso-octane/n-butanol-air mixtures was studied using the outwardly expanding spherical flame method and high-speed schlieren photography technique over a wide range of equivalence ratios and blending ratios at elevated initial temperatures. To interpret the dependence of the laminar flame speed on volume fraction of n-butanol in fuel blends (f vb), mechanistic interpretation was attempted through examining thermodynamic property, diffusive property and oxidation kinetics of the mixtures. Furthermore, the measured laminar flame speeds were fitted as a function of equivalence ratio, initial temperature and n-butanol fraction so as to provide some engineering merits.

关键词： Speed

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Experimental Investigation on Sodium Migration and Mineral Transformation in Ash Deposit During Gasification of Zhundong Coal Using a Drop Tube Furnace 9th

Experimental Investigation on Sodium Migration and Mineral T...

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9th International Symposium on Coal Combustion, ISCC 2019

作者： Liu, Chengchang Wang, Chang’an Wang, Chaowei Du, Yongbo Tang, Guantao Li, Guangyu Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9789811616563

Zhundong coal has attracted an ever-increasing concern due to its super-huge reserve but high content of alkali metals. Volatilized into the gaseous phase during the gasification process, alkali metals are extremely unfavorable for coal utilization. Gasification technology can promote the large-scale utilization of high-alkali coal. However, few efforts, if any, have been conducted on gasification of Zhundong coal. The present study aimed to elucidate the sodium migration and mineral transformation characteristics in coal ash deposition process under different gasification conditions, while the behavior of sodium migration and mineral transformation were further analyzed using Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-OES), X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. In this paper, the sodium migration characteristics in gasification process under different conditions were investigated by adding three sodium salts (NaCl, Na2CO3 and Na2SO4), kaolin and diatomite into coal, respectively. The effects of ash deposition time on sodium migration and mineral transformation characteristics in ash were also explored. The experimental results showed that the addition of sodium salt could increase the sodium content in the ash to a large extent. Kaolin and diatomite could solidify alkali metals in the gaseous phase during gasification process. As the ash accumulation time increased, the minerals such as chlorine, sulphur, and iron in the gaseous phase were easily bonded to the surface of the ash and reacted to form other crystal phases. The present study can provide guidance for the utilization of Zhundong coal and benefit the development of clean coal technology. © 2022, Tsinghua University Press.

关键词： Coal

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Experimental Study on the Characteristics of Liquid Layer and Disturbance Waves in Horizontal Annular flow

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Journal of Thermal Science 1999年第4期8卷 235-242页

作者： Li Weidong Zhou Fangde Li Rongxian Zhou Lixing Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China

The mechanism for transporting liquid from the bottom of the pipe to the top still to be established in the prediction of the film thickness distribution in horizontal annular two-phase flow. To resolve this issue, using five parallel-wire conductance probes, time records of local liquid film thickness at five circumferential positions were collected. The characteristics of circumferential liquid film thickness profiles and its variation with gas and liquid velocities were obtained. The basic features of probability distribution function, probability density function, auto-correlation, cross-correlation and power spectrum density function of the disturbance waves in angular flow were studied respectively. The characteristics of circumferential profiles of disturbance waves and its variation with gas and liquid velocities were presented.

关键词： two-phase flow annular flow liquid layer disturbance wares.

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Comparative study on PM emission of gasoline/propanol isomers

Comparative study on PM emission of gasoline/propanol isomer...

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9th Asia-Pacific Conference on Combustion, ASPACC 2013

作者： Gong, Jing Huang, Bin Gu, Xiaolei Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China

Propanol isomers are oxygenated fuels that have the potential to reduce the emission of engines. Particulate matter (PM) emissions of gasoline/propanol isomers blends have been comparatively investigated at different blending ratios of propanol isomers (0%, 10%, 20%, 40% and 100%) and EGR (Exhaust Gas Recirculation) rates (0% and 10%). Pure propanol isomers show significantly different emission characteristics compared to the other blends. PM number concentration decreases when EGR is introduced while little variation of PM mass concentration is observed. N-propanol mixtures produce higher PM number concentration than those of iso-propanol mixtures at the same blending ratio caused by their distinctively molecular structures and properties. The present study shows iso-propanol gives better performance as a gasoline additive compared to n-propanol.

关键词： Mixtures

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Pool boiling heat transfer enhancement by γ-Al2O3 /FC-72 nanofluids on a smooth surface 15

Pool boiling heat transfer enhancement by γ-Al2O3 /FC-72 na...

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15th International Heat Transfer Conference, IHTC 2014

作者： Kong, Xin Wei, Jinjia Ding, Jie Zhang, Yonghai State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong Uniersity Xi'an Shaanxi710049 China

The influence of γ-Al2O3/FC-72 nanofluids on pooling boiling heat transfer with a smooth surface was experimentally investigated. The fluorocarbon surfactant FSO-100 was also used in the experiment. In order to distinguish the effects of surfactant, four groups of contrast tests were designed as follows: base fluids (FC-72), base fluids with nanoparticles (γ-Al2O3+FC-72), base fluids with surfactant (FC-72+FSO-100) and nanofluids with surfactant (γ-Al2O3/FC-72+FSO-100). The results of nanofluids with surfactant showed that the heat transfer performance is enhanced compared with base fluid, but will weaken with the increase of particle concentration. In general, nanofluids can enhance the boiling heat transfer to some extent, and the enhancement is affected by the adjunction of surfactant and the sedimentation of nano-particules. Nanofluids prepared with only nanoparticles were not stable due to nonuniform distribution of the particles. The adjunction of surfactant (without nanoparticules) will lead to a significant deterioration in both heat transfer coefficient and CHF (Critical Heat Flux), but it can keep nanofluids stable and homogeneous to some degree for heat transfer enhancement.

关键词： Nanoparticles

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Numerical Simulation on Combustion Characteristics of Co-Firing Biomass Syngas and Coal in a 660 MW Utility Tower Boiler 9th

Numerical Simulation on Combustion Characteristics of Co-Fir...

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9th International Symposium on Coal Combustion, ISCC 2019

作者： Ma, Shihao Zhang, Yan Zhu, Zhengrong Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9789811616563

Utilize the biomass energy and adopt carbon capture and storage technologies could reduce the CO2 emission effectively. Biomass gasification is an effective ways to use the biomass. Co-firing biomass syngas with pulverized coal under oxy-fuel condition in utility boiler can combine the two advantages to reduce the CO2 emission. In this paper, a new proposed combustion mechanism was used to investigate the combustion characteristics of co-firing different types biomass syngas and coal in a 660 MW double reheat tower boiler. The influence of syngas composition and oxy-fuel condition on temperature distributions and flue gas components was analyzed when total input heat of the boiler was steady. The results show that the temperature and the emission of the NO and CO2 decrease in co-firing conditions, the NO mass concentration reduced up to 10.2% in co-firing cases. Biomass syngas with higher H2 and less CO and CH4 composition contributes to lower CO2 emission and higher boiler temperature, which can improve plant performance. The oxy-fuel condition also affects the combustion characteristics to some extent. With the increase of O2 volume fraction, the temperature increases and the O2 consumption decreases. Moreover, the NO mass concentration increases in oxy-fuel combustion when co-firing biomass syngas and coal with a mixing ratio of 0.1. This study offers reference for boiler’s operation and design optimization for biomass syngas co-firing. © 2022, Tsinghua University Press.

关键词： Coal

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Theoretical and experimental advances on heat transfer and flow characteristics of metal foams

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Science China(Technological Sciences) 2020年第5期63卷 705-718页

作者： WANG Hui GUO LieJin CHEN Kang School of Environmental Science and Engineering Donghua UniversityShanghai 201620China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Institute of Solar Engineering Technology Northwest Engineering Corporation LimitedPowerChinaXi’an 710065China

Open cell metal foam can be applied to greatly improve thermal performance of heat sink and heat exchanger,so that it has been widely used in the fields of thermal(or heat)control system of aerospace vehicle and energy utilization system and become a very important topic for research in the aerospace thermophysics field,and more and more attentions have been *** optimal design of metal foam heat transfer devices is based on the understanding the flow and heat transfer characteristics in metal *** article reviews some recent progresses of theoretical and experimental researches on heat transfer enhancement and flow characteristics of metal *** found that the pore cell simplification models of metal foams generally fall into four categories,among which the most commonly used cell model is Kelivin *** exploratory works performed by the current authors are also introduced,such as the effect of boundary conditions on the heat transfer enhancement;the theoretical modelling of interfacial convective heat transfer taking into account heat conduction between foam ligaments;and the flow characteristics under relatively high *** analytical results show that the flow characteristics of metal foam at relatively high speed are completely different from those at low speed,a further thorough study of the heat transfer and flow characteristics of metal foam is necessarily *** this paper,two types of partial filling techniques are *** heat transfer performance of partially filled tubes was evaluated by both the performance evaluation criteria and the performance evaluation plot of enhanced heat transfer techniques oriented for *** results show that the filling type of metal foam have a significant impact on its heat transfer enhancement ***,the filling method of metal foam should be further studied,in order to optimize the thermophysical properties of heat transfer devices.

关键词： metal foam effective thermal conductivity interfacial convective heat transfer coefficient heat transfer enhancement thermal radiation

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Simulation Investigation on NOx Emission Characteristics and Mechanisms During Co-combustion of Fossil Fuels with Different Fuel-Nitrogen Distributions via CHEMKIN 9th

Simulation Investigation on NOx Emission Characteristics and...

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9th International Symposium on Coal Combustion, ISCC 2019

作者： Wang, Chaowei Wang, Chang’an Zhao, Lin Yuan, Maobo Wang, Pengqian Du, Yongbo Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

ISBN: (纸本)9789811616563

There are over 100 million tons of semi-coke produced in China every year, and use of the semi-coke in utility coal-fired boilers is a promising approach. In this paper, a blending model of semi-coke and bituminous coal was established via CHEMKIN. The NOx emission was investigated by analyses of sensitivity and production rate, while the effects of stoichiometric ratio of main combustion zone, blending ratio, and combustion temperature on migration of fuel nitrogen were further elucidated. The simulation results showed that the conversion ratio of NOx increased monotonically with an increase in the stoichiometric ratio of main combustion zone. The temperature of plug flow reactor (PFR) I exhibited a significant effect on NOx emission, but other reactors had limited influences. The NOx conversion ratio was enlarged with the increase of semi-coke blending ratio. The influence of blending proportion on NOx emission was significant when the stoichiometric ratio of main combustion zone was small. Compared with high blending ratio, the main reactions with low blending ratio had stronger inhibitory effect on the formation of NO. The present study was of guiding significance for reducing NOx emission in the utility boilers co-firing semi-coke. © 2022, Tsinghua University Press.

关键词： Sensitivity analysis

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Synthesis of a novel ZnMoS4 photocatalyst and its performance for photocatalytic production of hydrogen

Synthesis of a novel ZnMoS4 photocatalyst and its performanc...

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16th World Hydrogen Energy Conference 2006, WHEC 2006

作者： Liang, Huirong Liu, Guanjie Zhang, Yaojun Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University 710049 Xi'an China

ISBN: (纸本)9781622765409

The production of hydrogen by photocatalytic decomposition of water using zinc tetrathiomolybdate catalyst was studied. Zinc tetrathiomolybdate catalyst was prepared by coprecipitation and hydrothermal method based on ZnSO 4 and self-prepared [NH4]2MoS4 crystal. It was characterized by XRD, XRF, BET and UV-Vis spectra. The photocatalytic activities of the catalysts were ascertained by the production of hydrogen in an aqueous Na2S-Na2SO3 solution under the ultraviolet and visible light irradiation. It was observed that the photocatalysts showed the visible-light photocatalytic activity, and the ZnMoS4 photocatalyst prepared under hydrothermal condition for about 24h had the highest activity.

关键词： Photocatalysts

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