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作者： Cai, Benan Zhang, Qi Weng, Yu Gu, Hongfang Wang, Haijun State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Pipelines such as the surge line and main pipe are easily subjected to thermal stratification and thermal fatigue as a result of the nonuniform temperature distribution in the nuclear power plants. When the surge line or main pipe subjected to thermal stratification and thermal fatigue keeps operating for long time, the pipe leakage may happen due to the existence of pipeline crack. When the fluids with high temperature and pressure leak in the crack, the water will evaporate quickly, which means this process belongs to spray flash evaporation process. The flash evaporation related to pipe leak was experimentally studied in the paper. The experiment was carried out under high temperature and high pressure with low spray rate. The temperature and relative humidity (T&H) variations over time were monitored in the experiment with installing T&H detectors. The T&H variations at different measurement positions and with different spray rates were analyzed, respectively. In addition, the effect of the dimensionless parameters including the Weber number and Jakob number was also investigated. Results indicated that the response speed increased with the increase of the spray flow rate. Higher Weber number and higher Jakob number led to higher evaporation rate. The slight pipe leakage can be predicted by using the (T&H) in the hazardous areas. Copyright © 2020 by ASME

关键词： Nuclear fuels

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flow and Thermal Analysis of the Transition Scheme between Micro-Channel and Micro-Jet Cooling Solution

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SSRN 2022年

作者： Guo, Yuming Fan, Liang-Liang Zhao, Liang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Xi'an Jiaotong University Xi'An China

With the rapid development of high-power electronics, the thermal management of these emerging devices is challenging due to the danger of ultra high heat flux and uneven temperature distribution. In this perspective, as promising cooling technologies, micro-channel and micro-jet cooling designs have been extensively investigated. In the past decade, certain heat-dissipation technologies based on micro-channel and micro-jet cooling have utilized geometrically identical heat sinks;however, their corresponding flow and thermal characteristics are dissimilar including micro-channel cooling technologies often have large temperature gradients as well as high heat transfer coefficients, while microjet technologies are more advantageous in terms of temperature distribution uniformity but larger pressure drop penalty. To characterize the enhanced heat-transfer mechanism driving this dissimilitude, a transition scheme between micro-channel and micro-jet was designed, featuring a gap on the channel fins top to provide extra flow area, and investigated experimentally and numerically. By controlling the volumetric flow ratio of the channel and jet, the flow and thermal characteristics of the transition scheme could be interchangeably transformed between the micro-channel and micro-jet. Moreover, we investigated the effect of the vortex generated by the jet impingement on channel bottom and fins top, an important factor causing the distinctions between the two schemes. The results revealed that the vortex in the stagnation zone enhanced the local heat-transfer coefficient corresponding to the channel bottom and promoted temperature uniformity;however, it caused the thermal boundary layer on the fins top to thicken. Although the vortex was favorable for the forced convection in the acceleration zone, the vortex intersections formed by adjacent jets introduced a greater pressure-drop penalty and flow blockage, which were not conducive to enhancing the heat transfer. Subsequently,

关键词： Vortex flow

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Dynamic modeling of an air-cooling supercritical power plant under temp oral variant ambient conditions 7

Dynamic modeling of an air-cooling supercritical power plant...

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7th International Conference on power engineering, ICOPE 2019

作者： Yan, Wenchen Han, Xiaoqu Chen, Nana Wu, Wenxiang Zhou, Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Air-cooling systems are widely used in coal-fired power plants, especially in areas rich in coal resources and short of water. To prompt its economic and safe operation, dynamic modeling is urgently required to acquire the power plant's characteristics under complex working conditions. In particular, the condensing pressure of the air-cooling unit is significantly affected by the ambient temperature, and the thermal power plant is a complicated energy system with serious nonlinearity. In many cases, it is difficult to establish the mathematical model of the system by traditional analytical methods. In the present work, a 1000 MW supercritical power plant thermal system was modeled and simulated by GSE simulation software. The model was developed according to the structural characteristics, incorporating boiler system, steam turbine system and direct air-cooling system. The simulation results were compared with the actual operation data of the power plant to validate the model. The relative errors of the simulation models under steady-state conditions were less than 3%, which indicates that the models have high accuracy. On this basis, the influence of condensing pressure on the standard coal consumption rate was obtained. It was shown that when the condensing pressure ranged between 5 kPa and 20 kPa, the coal rate increased by 1.6 g/kW∙h with 1 kPa increase in the condensing pressure. Then the boundary conditions of the system were changed. When the parameters changed, the changes of condensing pressure and power were monitored, so as to study the dynamic characteristics of the system. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Coal

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Synchronized Measurement Method of Burning Rate and Combustion Temperature of Solid Propellant Specimen

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SSRN 2023年

作者： Ni, Hu Fan, Rong Hu, Haihang Yang, Bin Wang, Zhixin Cao, Di Yang, Yang Shi, Zhiquan School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Space Propulsion Technology Research Institute Shanghai201109 China

To characterize solid propellant combustion, the measurement method of burning rate and combustion temperature of solid propellant specimen is developed that simultaneously combines shadow and radiation imaging methods. Shadow and radiation images of solid propellant specimen combustion are simultaneously captured by using light splitting and wavelength filtering imaging measurement system. Burning rate and combustion temperature of solid propellant specimen are synchronized obtained by burning surface identification and radiation image temperature measurement algorithm. Measurement accuracies of burning rate and combustion temperature of solid propellant specimen are validated by other independent measurement methods. Compared with target-line measurement method, the burning rate measurement relative deviation is less than 3.1%. Compared with thermocouple measurement, the temperature measurement relative deviation is less than 1.7%. On this basis, the synchronized measurements of burning rate and combustion temperature of different formulations of solid propellant specimens under different working conditions are carried out. The results show that burning rate and combustion temperature are important characterization parameters of solid propellant combustion performance. For a certain formula solid propellant specimen, the burning rate can be greatly increased by increasing the pressure, but the combustion temperature is not much increased. Therefore, the synchronized measurement of burning rate and combustion temperature can provide more direct data support for the evaluation of solid propellant combustion performance. © 2023, The Authors. All rights reserved.

关键词： Solid propellants

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Numerical study on drop-on-demand droplet formation dynamics 7

Numerical study on drop-on-demand droplet formation dynamics

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7th International Conference on power engineering, ICOPE 2019

作者： Zhu, Maoguo Chong, Daotong Zhao, Quanbin Chen, Weixiong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Inkjet printing technology has been applied in many industrial fields for its significant usefulness. The drop-on-demand droplet formation dynamics was studied numerically based on the VOF and CSF method. Droplet formation was modeled by imposing a vertical velocity pulse waveform perturbation. The effects of printhead geometry and fluid properties on droplet ejection stability were analyzed. Simulation results make clear that choosing an appropriate printing fluid with relatively lower density and viscosity or higher surface tension can improve the droplet ejection stability. Designing the printhead with a larger inclination of outlet is also a key way to improve the droplet ejection stability. In addition, droplet ejection stability becomes better as Z increased or Ca decreased. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Stability

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Selectivity catalytic reduction of NO by CO over Fe-Cu oxides supported on rice hull Ash(Rha) 7

Selectivity catalytic reduction of NO by CO over Fe-Cu oxide...

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7th International Conference on power engineering, ICOPE 2019

作者： Teng, Zhaohui Fu, Liang Li, Na Zhou, Qulan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xian710049 China

The present work contains the studies of catalytic reduction of NO with CO over 20 wt.% bimetallic Fe-Cu transition metal oxides supported on rice hull ash (RHA) and γ-Al2O3, which were prepared by various procedures. All catalysts contained CuO and Fe2O3 alongside with CuFe2O4. The catalytic activity kinetics for NO and CO reduction reaction mechanism was obviously improved over the synthesized RHA when compared to alumina support. And bimetallic metal catalyst Fe2Cu1/RHA demonstrated a high conversion of NO at all the temperatures examined. This was due to the strong interaction of Cu-Fe with the amorphous silica and activated carbon in RHA and high dispersion on the supporter. NO was almost reacted to N2 over Fe2Cu1/RHA from room temperature to 500℃ and O2 has little influence on it in our experiment conditions. About 100% CO was oxidized after 150℃ over Fe2Cu1/RHA. All the materials showed an unchanged stability over the period of 20h. Metallic copper and iron were the active species. The present results suggest that bimetallic Fe-Cu transition metal oxides supported on rice hull ash (RHA) can be used as an applicable catalyst to selectively reduce NO and CO. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Reduction

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Studies on high temperature corrosion behavior of water wall materials under cyclic temperature 7

Studies on high temperature corrosion behavior of water wall...

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7th International Conference on power engineering, ICOPE 2019

作者： Liu, Zhuhan Wu, Zhengyu Li, Na Zhou, Qulan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

In this study, the corrosion behavior of water wall materials under cyclic temperature was studied. Corrosion products (XRD and EDS), corrosion morphology (SEM detection) and corrosion effects on residual matrix metal (SEM detection) were compared after different corrosion times to obtain the corrosion behavior under cyclic temperature conditions. There is no significant difference between the corrosion products of the sample at the circulating temperature and the corrosion products at the constant temperature. The corrosion surface layer is iron oxide, but according to the cross-sectional morphology it can be clearly observed that under the cyclic temperature condition, there is a certain increase in the corrosion layer thickness and the corrosion scales is broken with less protection. As the composition of T23, Cr didn't participate in the corrosion reactions to form a protective Cr2O3 protective layer, which is different in other materials. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： High temperature corrosion

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Conducting Polymers Meet Lithium-Sulfur Batteries:Progress,Challenges,and Perspectives

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Energy & Environmental Materials 2023年第5期6卷 159-182页

作者： Xin Chen Chengcheng Zhao Kai Yang Shiyi Sun Jinxin Bi Ningrui Zhu Qiong Cai Jianan Wang Wei Yan Department of Environmental Science and Engineering State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China Xi'an Key Laboratory of Solid Waste Recycling and Resource Recovery Department of Environmental EngineeringXi'an Jiaotong UniversityXi'an 710049China Advanced Technology Institute University of SurreyGuildfordSurrey GU27XHUK College of Arts College of Landscape Architecture Fujian Agriculture and Forestry UniversityFuzhou 350108China Department of Chemical&Process Engineering Faculty of Engineering and Physical Sciences University of SurreyGuildford GU27XHUK

Lithium-sulfur(Li-S)batteries have attracted increased interest because of the high theoretical energy density,low cost,and environmental *** polymers(CPs),as one of the most promising materials used in Li-S batteries,can not only facilitate electron transfer and buffer the large volumetric change of sulfur benefiting from their porous structure and excellent flexibility,but also enable stronger physical/chemical adsorption capacity toward polysulfides(LiPSs)when doped with abundant heteroatoms to promote the sulfur redox kinetics and achieve the high sulfur *** review firstly introduces the properties of various CPs including structural CPs(polypyrrole(PPy),polyaniline(PANi),polyethylene dioxothiophene[PEDOT])and compound CPs(polyethylene oxide(PEO),polyvinyl alcohol(PVA)and poly(acrylic acid)[PAA]),and their application potential in Li-S ***,the research progress of various CPs in different components(cathode,separator,and interlayer)of Li-S batteries is systematically ***,the application perspective of the CPs in Li-S batteries as a potential guidance is comprehensively discussed.

关键词： conducting polymers Li-S batteries modified materials polysulfides

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Ventilation and cooling of wind generator: A numerical study and experimental verification 7

Ventilation and cooling of wind generator: A numerical study...

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7th International Conference on power engineering, ICOPE 2019

作者： Ao, Yunjin Li, Na Zhou, Qulan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

In the wind generator, a large amount of heat is generated during the operation, which usually causes severe temperature rise and decrease of efficiency. By coupling fluid dynamics and heat transfer, a numerical method has been developed to calculate the velocity filed and temperature distribution of a common air-cooled doubly-fed wind generator. The numerical results have been verified by the experiments. The results show that the flow resistance is higher in the center in the axial direction, thus the temperature is much higher than the ends. In the height direction, there locate the most dangerous points and the temperature rise is about 110K. In the circumference direction, there are regularity of fluctuation and can assist in finding the dangerous points. The variations of heat source and cooler power as well as rotation speed all affect the temperature rise of the generator. The regularity and method of this study can be applied to similar generators or generators of other forms, thus advice can be given for the design, manufacture, operation and maintenance of wind generators. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Temperature distribution

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Experimental study on preparation of amorphous SiO2 by fluidized bed combustion of rice husk 7

Experimental study on preparation of amorphous SiO2 by fluid...

引用

7th International Conference on power engineering, ICOPE 2019

作者： Yao, Yashu Xu, Heng Tan, Jingkao Hu, Zhengtao Zhou, Qulan Li, Na State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The rice husk ash (RHA) contains a large amount of amorphous silica having a large specific surface area and high activity, but after combustion of the rice husk the SiO2 is easily crystallized, which deteriorate the performance. Therefore, it is necessary to study the crystallization process of silica in combustion for the preparation of excellent rice husk ash. On the self-built fluidized bed experimental system, the combustion characteristics of rice husk and the pore characteristics of RHA under different excess air coefficients were studied. It was found that when the excess air ratio was between 0.8 and 0.9, the silica remained unchanged, and the specific surface area of rice husk ash is larger. Meanwhile, the furnace temperature is higher, which is conducive to the utilization of heat;when the excess air ratio is greater than 1, the crystallization of rice husk ash is more serious. In conclusion, it should be burned when the excess air ratio is less than 1 in order to prepare RHA with large specific surface area by direct combustion method. © ICOPE 2019 - 7th International Conference on power engineering, Proceedings. All rights reserved.

关键词： Silica

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