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flow Fluctuations and flow Friction Characteristics of Lead-Bismuth Eutectic in a Vertical Tube Under Rolling Conditions

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SSRN 2022年

作者： Liu, Zhipeng Zhao, Yafeng Tian, Wenxi Wang, Chenglong Qiu, Suizheng Su, Guanghui H. School of Nuclear Science and Technology Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

The effects of rolling motion on the flow characteristics of lead-bismuth eutectic in a vertical circular tube are investigated experimentally. The results show that the pressure drop and flow rate of the forced LBE circulation fluctuate under rolling conditions. The effect of rolling motion on the flow characteristics decreases with the increase of the corresponding static Reynolds number. The rolling motion may increase the time-averaged frictional resistance coefficient of the LBE when flow rate is low. The critical value of the impact Reynolds number is about 125,000. As a result, the time-averaged flow rate decreases. The analysis shows that it is mainly the transverse additional force caused by the rolling motion increases the frictional resistance of the LBE. An empirical correlation is established to predict the frictional resistance coefficient under rolling conditions. This study may be useful in the thermal-hydraulic analysis of LBE as a working fluid under moving conditions. © 2022, The Authors. All rights reserved.

关键词： Reynolds number

Simulation Study on Heat Exchangers Characteristics of Solar Thermal Steam System Based on Aspen Plus

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Simulation Study on Heat Exchangers Characteristics of Solar...

Algorithms, High Performance Computing and Artificial Intelligence (AHPCAI), International Conference on

作者： Pengfei Chen Kang Chen Huaiwu Peng Yanlong Zhang Baercheng Bawaa Qiuyang Zhao Institute of Solar Engineering Technology Northwest Engineering Corporation Limited Power China Xi'an China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an China

In the thermal recovery project of thick oil, there are high standards for steam temperature and flow rate. The solar thermal steam supply system can convert unstable solar energy into stable and efficient carrier heat, which can be used to transfer heat to low-temperature water to produce high-temperature steam and achieve a clean and low-carbon steam supply. The rated pressure of steam and the split ratio of molten salt in the heating system have a great influence on the demand area and heat load of solar panels. In this paper, a simulation is made on the solar thermal steam supply system based on Aspen Plus. The simulation result shows that the increase in pressure will cause a growth in the area of the photothermal concentrator field but will reduce the area used for photovoltaic panels. At the same time, it reduces the heat load of the evaporator and extends its service life. The split ratio affects the molten salt temperature at the outlet of the superheater and the reheater. When the split ratio increases, the heat transfer temperature difference between the two ends of the superheater heat flow decreases, and the heat transfer temperature difference of the reheater grows bigger. Therefore, the molten salt temperature flowing out of the reheater rises.

关键词： Water Temperature Costs Oils Simulation Water heating Solar heating

Thermal-Hydraulic Characteristics of Helical Cruciform Single Rod Based on Cfd Investigation

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SSRN 2024年

作者： Chen, Yiwen Zhang, Dalin Jiang, Dianqiang Deng, Jian Zhang, Xisi Wang, Xinan Tian, Wenxi Qiu, Suizheng Su, Guanghui State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China China Institute of Atomic Energy Beijing611731 China

To increase power density in nuclear reactors, the helical cruciform fuel (HCF) is designed as a fundamental element. HCF takes advantages of strong mixing effects, self-supporting features, and strengthened heat transfer, potential to increase the fuel performance in nuclear reactors. In this paper, friction factor and heat transfer coefficient empirical correlations of HCF single rod cooled by water were proposed using a geometric dimensionless number based on numerical simulation. The velocity field, and temperature distribution were obtained to discuss influences of geometric sizes on the fuel performance. Finally, correlations with a geometric dimensionless number were validated with various cases, whose application conditions were also proposed and discussed. This paper provides a guide for study of heat transfer and fluid flow in helical structures, and a reference for establishment of reactor system model using helical cruciform fuels. © 2024, The Authors. All rights reserved.

关键词： Heat transfer coefficients

Under-Deposit Corrosion Behavior and Dynamic Deliquescence Properties of Ammonium Salts Covered on Pipelines and Components in a Crude Oil Distillation Column: Experimental and Theoretical Studies

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SSRN 2022年

作者： Li, Ruidong Chen, Jukai Wang, Yueshe State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi'An710049 China School of Chemical Engineering & Technology China University of Mining and Technology Xuzhou221116 China

Electrochemical experiments based on the interdigital electrodes of SAE 1020 steel and atomic simulation were performed to investigate the under-deposit corrosion behavior and dynamic deliquescence properties of ammonium salts. In-situ electrochemical measurements demonstrate that the deliquescence of ammonium salts affects the evolution of the interface, and the surface characterization results proved that the critical state of moisture absorption leads to the most severe corrosion. Additional ab initio molecular dynamics simulations suggest that the H transport chain impacted by the hydrolysis of NH4+ leads to a variation in the charge state of the system, which may triggering corrosion. © 2022, The Authors. All rights reserved.

关键词： Steel corrosion

Low-energy and accelerated hydrogen release from MgH2–5 wt% NaTiOxH catalyzed hydrogen storage reactor by graphite responsive microwave

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Journal of Magnesium and Alloys 2025年

作者： Wang, Bofei Wu, Zhen Liu, Honghao Yang, Fusheng Zhang, Zaoxiao Yao, Jing Li, Qian Cao, Hujun Li, Bo State Key Laboratory of Fluorine & Nitrogen Chemicals School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow for Power Engineering Xi'an Jiaotong University Xi'an710049 China National Engineering Research Center for Magnesium Alloys Chongqing University Chongqing400044 China Dalian National Laboratory for Clean Energy Dalian Institute of Chemical Physics Chinese Academy of Sciences Dalian116023 China Faculty of Engineering Electrical Energy Management Group University of Bristol BristolBS8 1QU United Kingdom

Owing to high thermal stability and large reaction enthalpy, MgH2 has high reaction temperatures and sluggish reaction kinetics in the dehydrogenation process, which consumes lots of energy. To achieve hydrogen release with low energy consumption, accelerated reaction rate, and high heating uniformity, this paper proposes a novel method of graphite responsive microwave-assisted thermal management with NaTiOxH catalyst. A multi-physics model of the 5 wt% NaTiOxH catalyzed MgH2 reactor integrated with a microwave generator is developed to investigate the reaction, heat and mass transfer process of hydrogen release. It is found that the graphite responsive microwave heating method could improve the temperature uniformity of reaction bed, reduce the energy consumption by at least 10.71% and save the hydrogen release time by 53.49% compared with the traditional electric heating method. Moreover, the hydrogen desorption thermodynamics could be improved with the increase of microwave power. The hydrogen release time is shortened by 19.55% with the increase of 20 W microwave power. Meanwhile, it is also concluded that the microwave excitation frequency of 2.1 GHz and the graphite content of 2 wt% have better heating performance. Therefore, it can be verified that the graphite responsive microwave heating helps to low-energy and accelerated hydrogen release from MgH2 hydrogen storage reactor. © 2025

关键词： Reaction rates

Zif-L(Co) Derived Cobalt Doped In2o3 Hollow Nanofibers with High Surface Activity for Efficient Formaldehyde Gas Sensing

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SSRN 2023年

作者： Zhu, Lei Wang, Jianan Liu, Jianwei Wang, Ze Sun, Shiyi Li, Mingtao Yan, Wei Xi’an Key Laboratory of Solid Waste Resource Regeneration and Recycling State Key Laboratory of Multiphase Flow Engineering Xi’an Jiaotong University Xi’an710049 China School of Physics and Electrical Engineering Weinan Normal University Chaoyang Street Weinan714099 China School of Chemistry and Chemical Engineering Xi’an University of Science & Technology Xi’an710054 China

Gas sensors based on semiconductor metal oxides are identified as a highly promising candidate for toxic gas detection, yet they still suffer from high operating temperature due to low surface activity at low temperature. To address this issue, we present an elaborate design for the homogeneous functionalization of ZIF-L(Co) derived cobalt (Co) catalysts into hollow In2O3 frameworks, aiming to highly activate the redox capacity and catalytic efficacy of the In2O3 sensor to HCHO gas. Benefiting from the Co catalysts doping boosts the catalytic activity and generates abundant oxygen vacancies, the optimized 1 wt% Co-doped In2O3 HNFs sensor exhibits a high response of 40.4 toward 100 ppm HCHO at a moderately low temperature of 180 ℃, which is 4 times higher than that of pristine In2O3 HNFs. Moreover, 1 wt% Co-doped In2O3 HNFs sensor has virtues of high selectivity and excellent long-term stability for HCHO sensing. This study highlights the important influence of Co catalyst on the modulation of surface active sites of metal oxides-based sensors, inspiring the development of cost-effective sensors for indoor hazardous gas monitoring. © 2023, The Authors. All rights reserved.

关键词： Cost effectiveness

Research on a Poly-Generation System for Gas-Biochar-Heat-Electricity by Supercritical Water Gasification of Biomass Waste

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SSRN 2024年

作者： Wang, Cui Jin, Hui School of Water and Environment Chang'an University Xi’an710054 China Key Laboratory of Subsurface Hydrology and Ecological Effect in Arid Region of the Ministry of Education Chang'an University Xi’an710054 China Key Laboratory of Eco-hydrology and Water Security in Arid and Semi-arid Regions of Ministry of Water Resources Chang’an University Xi’an710054 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China Ministry of Education of China Chongqing University Chongqing400044 China

Biomass energy is renewable and rich in the world, providing a solution for the shortage in fossil fuel and serious environmental pollution. Proposing efficient utilization method of biomass waste demands urgent attention. Supercritical water gasification (SCWG) process is a potential technology. In this work, a poly-generation system based on SCWG was developed to convert biomass waste to gas, biochar, heat and electricity. Firstly, mass, energy, and exergy flow were calculated at the typical condition. Subsequently, impact of various operating parameters, including gasification temperature, mass flowrate of preheated water, biomass concentration, on the hydrogen-rich syngas yield, generated electricity, thermodynamic performance of the system was investigated. The result demonstrated that the exergy loss primarily occurred on cooler, reactor, heat exchanger and preheater, accounting for more than 90% of total exergy loss under different conditions, arising from irreversible reaction, heat transfer and heat dissipation. Higher temperature, higher biomass concentration and more preheated water exerted a positive effect for hydrogen-rich gas production and supplied heat energy, while these parameters were disadvantageous to exergy efficiency. Biochar energy was primarily affected by biomass concentration. Energy efficiency increased with preheated water quantity and biomass concentration rising, and impact of biomass concentration was more significant. Conversely, evaluated gasification temperature displayed an adverse effect on energy efficiency. The maximal exergy efficiency reached about 58.3% at 550℃, biomass concentration of 33%, preheated water mass flowrate of 900 kg·h-1 © 2024, The Authors. All rights reserved.

关键词： Biomass

Dye visualization of the wake of a near-wall particle in response to a periodic oscillation

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Measurement: Sensors 2021年 13卷

作者： Li, Xing Zhang, Haibin Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'anShaanxi710049 China

In turbulent dispersed multiphase flows, the interaction between the particle wake and the ambient turbulent fluctuation can be crucial for the change of the multiphase system. This issue is extremely complex due to the chaotic nature of the turbulence. In this paper, the ambient turbulent fluctuation of certain frequency is simulated by the Karman vortex street behind a horizontally placed cylinder, and the response of the wake of a stationary near-wall particle to the oncoming oscillation is investigated. The dye visualization is used to mark the vortex structures of the wake and the oncoming oscillation, respectively, and power spectrum analysis is conducted to reveal the features in the frequency domain. Results show that at relatively low Rep, the oncoming oscillation has little effect on the wake. As Rep increases, the response of the wake to the oncoming oscillation is evident. High-frequency fluctuation dissipates very fast and only exists near the particle. On the contrary, the life span of the low-frequency fluctuation lasts for a much longer period and exists far downstream. In addition, the self-induced vortex shedding is not notable and is overwhelmed by the oncoming oscillation. © 2020 The Author(s)

关键词： Wakes

Numerical study on oxy-fuel co-combustion of semi-coke and coal in utility boiler: Insight into NOx emission and combustion efficiency 7

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Numerical study on oxy-fuel co-combustion of semi-coke and c...

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