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Performance Prediction and Geometry Optimization of Ejector in Pemfc System Using Coupled Cfd-Bpnn and Genetic Algorithm

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SSRN 2024年

作者： Pang, Zihui Han, Jiquan Feng, Jianmei Diao, Anna Yao, Yanchen Peng, Xueyuan School of Energy and Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China Shanghai Marine Diesel Engine Research Institute Shanghai Shanghai201108 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

The ejector is a promising hydrogen recirculation device in proton exchange membrane fuel cell (PEMFC) systems. However, the limited entrainment performance of the ejector at wide operating conditions hinders its development and widespread application in PEMFC systems. To address this challenge and design a high-performance ejector adapted to the wide power range of PEMFC systems, a backpropagation artificial neural network (BPNN) model with computational fluid dynamics (CFD) simulation data is developed. The sensitivity analysis of geometric parameters based on the CFD model reveals that the nozzle throat diameter (Dt) and the mixing chamber diameter (Dm) exert the most pronounced impact on the entrainment performance, with average influence rates of 24% and 57%, respectively. Furthermore, two advanced multi-objective genetic algorithms (LWGA and NSGA-II methods) are applied to improve ejector performance. The LWGA method proves effective in elevating the overall ejector performance, achieving a remarkable enhancement in entrainment performance of up to 7.9%. On the other hand, the NSGA-II method is favorable for expanding the operational power range of the ejector by 30%, as well as a 4.5% increase in overall ejector performance. This work provides a robust framework for designing and optimizing high-performance ejectors in high power PEMFC systems. © 2024, The Authors. All rights reserved.

关键词： Sensitivity analysis

Experimental Investigation on flow and Heat Transfer Characteristics of Helium in Rectangular Narrow Slit Channel

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SSRN 2024年

作者： Li, Changzhong Wang, Chenglong Sun, Yanyu Chen, Ronghua Tian, Wenxi Su, Guanghui Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering China Department of Nuclear Science and Technology Shaanxi Key Lab. of Advanced Nuclear Energy and Technology Xi’an Jiaotong University Shaanxi Xi’an710049 China China Nuclear Power Engineering Co. Ltd. Beijing100840 China

Helium is utilized as coolant in high temperature gas cooled reactors. Rectangular narrow slit channels are commonly present in the core. The flow and heat transfer properties of helium significantly affect the core temperature and flow distribution. This paper experimentally investigates the flow and heat transfer properties of high temperature helium in rectangular narrow slit channel. The Reynolds numbers ranged from 468 to 5327, the temperature ratio of wall to bulk from 0.91 to 1.22, the helium outlet temperature up to 944 K, and the maximum heat flux density up to 0.101 MW/m². In the experiment, the total and local convective heat transfer coefficients, along with the friction factors, are measured. Correlation equations for the Nusselt number and friction factor with respect to Reynolds number are derived. The primary findings are as below: the friction factors of helium in rectangular narrow slit channels are significantly larger than those calculated by current empirical correlations. In the turbulent zone, the measured local Nusselt numbers are in excellent accordance with the Gnielinski correlation;however, a significant discrepancy exists in the laminar zone. New flow heat transfer correlation equations are proposed on the bases of experimental data. Upon comparison, the total Nusselt numbers fall in the error of 10%, and almost all local Nusselt numbers and the friction factors fall in the error of 20%. © 2024, The Authors. All rights reserved.

关键词： Helium

A new strategy to produce calcium carbide-acetylene from integrated multi-level low carbon construction driven by biomass

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A new strategy to produce calcium carbide-acetylene from int...

作者： Wang, Hongxia Li, Xiaoli Wu, Zhen Shen, Wei Chen, Kai Hong, Bingqing Zhang, Zaoxiao School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi'an710049 China Co. Ltd Level 10-15 Block A Sunland International No.999 Zhouhai Road Pudong New Zone Shanghai200131 China

A highly efficient and clean biomass energy-based calcium carbide-acetylene production system, including low-carbon energy supply, solid waste recycling and cascade utilization of waste heat, has been developed for the conventional energy-intensive and highly polluting fossil fuel-dependent calcium carbide industry. This system supplies the carbide-acetylene production plant with energy from the gasification of biomass and converts the plant's solid waste carbide slag into the calcium feedstock required by the plant. The waste heat from the plant's high-temperature exhaust gases is recycled and used via the multi-stage heat exchange, so that the energy cascade conversion and utilization is achieved. A simulation model of the plant is created in Aspen Plus, and a mathematical model for the biomass gasification process and cycle compensation of the calcium source through the Fortran language is written and embedded. When calculating the carbon consumption and CO2e emissions of the system, it was found that the carbon consumption and CO2e emissions of the conventional process were 5.43 t Coal·t−1C2H2 and 2.25 t CO2e·t−1C2H2, respectively. However, the carbon consumption of the new process was reduced by 65.19%, and carbon emissions by 27.24% in comparison. The energy analysis shows that the energy efficiency of the system is 36.21% for the conventional process and 44.82% for the new processes. The exergy analysis of the effective energy shows that the exergy efficiency of the new process is 73.20%, which is 52.98% better than that of the conventional process. Introduction of an index, the levelized income of acetylene product (LIOA), to characterize the product income of the system. When the price of acetylene is between 2.23 $/kg and 4.19 $/kg, the LIOA for the conventional and the new processes are 1.41 $/kg to 3.38 $/kg and − 1.28 $/kg to 0.68 $/kg, respectively. It is worth noting that the critical price (PCC2H2) for products generating net revenue from the new pro

关键词： Biomass

Experimental research on the characteristics of steam-water counter-current flow in the Pressurizer Surge Line assembly

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Experimental Thermal and Fluid Science 2018年 96卷 180-191页

作者： Jiangtao Yu Dalin Zhang Leitai Shi Zhiwei Wang Wenxi Tian G.H. Su S.Z. Qiu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University 28 Xianning West Road Xi’an 710049 China Shaanxi Key Lab. of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University 28 Xianning West Road Xi’an 710049 China

To investigate Counter-Current flow (CCF) characteristics in the Pressurizer Surge Line (PZR SL) assembly of the large advanced passive nuclear reactors, steam-water CCF experiments are carried out on a stainless steel test section, which is a 1:4 scaled-down model of the AP1000 PZR SL assembly. The inner diameter of the test PZR SL pipe is 90 mm, which also belongs to the large-diameter pipes, as same as the prototype PZR SL pipe, in the field of Counter-Current flow Limitation (CCFL) researches. The present steam-water CCFL experiments are conducted under normal pressure and saturated temperature, with the PZR simulator collapse water level ranging from 350 to 900 mm. CCFL becomes severer at higher steam flow rate, and the most limiting CCFL effect locates between the PZR simulator bottom head and the vertical part of PZR SL pipe. The onset of CCFL and zero liquid penetration (ZP) are two critical conditions in the CCF development process, dividing the process into three stages: Before-CCFL, Partial-CCFL, and CCFL-ZP. According to the local CCFL conditions, the development of the CCFL process is also divided into four-regions since onset of CCFL. The present steam-water CCF data are well normalized in terms of dimensionless Kutateladze (Ku) numbers, and a Ku-type empirical partial CCFL correlation is developed. The comparisons of the present CCF data and partial CCFL correlation with the CCF data and correlations of former experiment researches validate that the present empirical partial CCFL correlation is conservative to predict steam-water partial CCFL in the prototype PZR SL assembly of the large advanced passive nuclear reactors.

关键词： Steam-water counter-current flow Partial CCFL correlation Pressurizer surge line assembly Advanced passive nuclear reactors ADS Automatic Depressurization System ADS1-3 First to Third Stages of ADS ADS4 Fourth Stage of ADS CCF Counter-Current flow CCFL Counter-Current flow Limitation CCFL-1 The 1st grade of CCFL region CCFL-2 The 2nd grade of CCFL region CCFL-3 The 3rd grade of CCFL region CCFL-L Local CCFL at the T-junction of HL pipe and PZR SL pipe CCFL-S Local CCFL along the PZR SL pipe CCFL-U Local CCFL at the location between the PZR simulator bottom head and vertical part of PZR SL pipe CCFL-ZP Zero liquid penetration region or stage CMT Core Makeup Tank COCF Co-Current flow HL Hot Leg IRWST In-containment Refueling Water Storage Tank Ku Kutateladze PRHR Passive Containment Cooling System PWRs Pressurized Water Reactors PZR SL Pressurizer Surge Line RC Reactor Core RCS Reactor Coolant System RPV Reactor Pressure Vessel SBLOCAs Small-Break Loss-of-Coolant Accidents ZP zero liquid penetration

Carbon Exergy Footprint to Evaluate the Greenhouse Impact of Operating Units

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Energy Procedia 2017年 105卷 3179-3184页

作者： Zhen Qin Xiaomei Wu Zaoxiao Zhang School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an 710049 P.R. China

Increasingly serious global warming caused by greenhouse gases has urged more and more focus on the sustainability. Exergy and carbon footprint are generally considered as two separate indicators to assess the greenhouse effect and sustainability of industrial production. In this paper we propose carbon exergy footprint (CEF) for quantitatively associating carbon footprint with exergy to evaluate the greenhouse effect of operating units. The indicator synthesizes the advantages of exergy and carbon footprint. Specific physical meaning for this novel indicator is illustrated on the basis of the second law of thermodynamics and life cycle assessment. The process of water-gas shift is chosen as the case for elaborating the behavior of CEF. Results show that CEF is competent for the objective evaluation for the greenhouse effect of the operating units. Additionally, CEF also maintains consistency with the conventional exergy analysis in terms of sustainability.

关键词： Carbon exergy footprint operating unit greenhouse impact indicator

Sensitively Detection of Ascorbic Acid in Orange Samples with Ionic Liquid Functionalized Carbon Dots and Lanthanide Complexes

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SSRN 2024年

作者： Li, Ying Xia, Ji-Ji Lu, Jia-Zhen Wang, Zi-Long Wang, Mi-Tang School of Materials and Chemistry University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China

In the food industry, ascorbic acid (AA) is widely used as an antioxidant. However, the concentration of AA is influenced by various factors, including temperature, time, and pH value during food preparation and storage, leading to its instability in content. This makes the accurate detection of AA content particularly important. Precise determination of AA content in food and pharmaceuticals is crucial for ensuring the adequate intake of essential vitamins and maintaining good health. Herein, we have developed a successful preparation method of an imidazole-based ionic liquid functionalized CDs hybrids APM-CDs. A novel photo functional hybrid probe Eu3+@APM-CDs was obtained via an ion-exchange reaction between APM-CDs and lanthanide complex Eu(DPA)3. The obtained hybrid probe was extensively characterized in detail. What’s more, the results show that the FL intensity of Eu3+@APM-CDs has a good linear response to AA concentrations in the range of 0-500 μM (R2 = 0.99), with a detection limit of 80 nM. The fluorescence probe demonstrates good selectivity and sensitivity toward AA and has the potential for significant application in AA detection by simplifying procedures and reducing interference from impurities. © 2024, The Authors. All rights reserved.

关键词： Probes

Depth from Defocus Technique for High Number Densities and Non-Spherical Particles

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SSRN 2024年

作者： Xu, Rixin Huang, Zuojie Gong, Wenchao Zhou, Wu Tropea, Cameron School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering Shanghai China Institute for Fluid Mechanics and Aerodynamics Technical University of Darmstadt Darmstadt Germany

The Depth from Defocus (DFD) imaging technique for measuring the size and number concentration of particles in a dispersed two-phase flow has up to now been restricted to relatively sparse particle densities and to identifying only spherical particles. The present study examines two advancements to the technique, widening its range of application significantly. The first advancement introduces an image processing procedure which can identify and size particle images which are overlapping. This increases the tolerable number concentration of particles which can be identified and processed within the measurement volume. The second advancement explores the possibility of determining the size and position of non-spherical particles within an observation volume. These enhancements are experimentally validated using a dedicated apparatus in which particles of known size, shape and degree of overlapping images can be systematically varied. This experimental setup provides benchmark data to quantify the accuracy and limitations of the processing algorithms. © 2024, The Authors. All rights reserved.

关键词： Two phase flow

Microwave-assisted synthesis of bimetallic NiCo-MOF-74 with enhanced open metal site for efficient CO 2 capture

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Environmental Functional Materials

Environmental Functional Materials 2022年第3期1卷 253-266页

作者： Changwei Chen Mohammadreza Kosari Meizan Jing Chi He State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi PR China Department of Chemical and Biomolecular Engineering Faculty of Engineering National University of Singapore 10 Kent Ridge Crescent 119260 Singapore Department of Chemistry Key Laboratory of Organic Optoelectronics & Molecular Engineering of Ministry of Education Tsinghua University Beijing PR China National Engineering Laboratory for VOCs Pollution Control Material & Technology University of Chinese Academy of Sciences Beijing 101408 PR China

Metal–organic frameworks (MOFs) containing two different inorganic metal nodes (known as bimetallic MOFs) could exhibit enhanced CO 2 adsorption compared to their monometallic counterparts. Herein, a series of bimetallic NiCo-MOF-74 synthesized by microwave-assisted method were investigated for CO 2 adsorption. It was revealed that narrow micropore channel with open metal site (OMS) of the bimetallic NiCo-MOF-74 influence CO 2 binding affinity and CO 2 /N 2 adsorption. The CO 2 uptake of Ni 1 Co 1 -MOF-74 at 0 °C and 1 bar (100 kPa) was 8.30 mmol g −1 which is higher than those of Ni-MOF-74 (3.99 mmol g −1 ), Ni 6 Co 1 -MOF-74 (3.62 mmol g −1 ), Ni 1 Co 6 -MOF-74 (6.40 mmol g −1 ) and Co-MOF-74 (5.03 mmol g −1 ). While this could be related to the high specific surface area of Ni 1 Co 1 -MOF-74, Ni 1 CO 2 -MOF-74 with relatively low specific surface areas still shows good CO 2 adsorption capacity up to 5.70 mmol/g, which is higher than those of adsorbents Ni-MOF-74, Ni 6 Co 1 -MOF-74 and Co-MOF-74, indicating that adsorption performance mainly relies on coordinated metals. Ni 1 Co 1 -MOF-74 showed remarkable recyclability performance, ranking selectivity of CO 2 /N 2 reach up to 34, and suitable isosteric heat (31–23 kJ mol −1 ), manifesting a great probability for industrial CO 2 capture. As revealed, incorporated Ni 2+ /Co 2+ nodes within Ni 1 Co 1 -MOF-74, which are acting as active and open sites for CO 2 capture, led to the synergetic effects comprising of micropores as well as dense dual-metal sites.

关键词： Bimetallic metal–organic frameworks NiCo-MOF-74 Microwave-assisted synthesis Open metal site CO 2 capture

Removal of gaseous elemental mercury and nitrogen oxides in bubbling reactors with sodium hypochlorite aqueous solution

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Removal of gaseous elemental mercury and nitrogen oxides in ...

International Conference on power engineering, ICOPE 2015

作者： Li, Na Chen, Lu Zhou, Qulan Shen, Jizhao State Key Laboratory of Multiphase Flow in Pow er Engineering Xi'an Jiaotong University Xi'an City Shaanxi Province710049 China Collaborative Research Center for Energy Energy Engineering Institute of Industrial Science University of Tokyo 4-6-1 Komaba Meguro-ku Japan Yangzhou Chenguang Special Equipment Co. Ltd. Yangzhou225800 China

The conditions for sodium hypochlorite aqueous solution (NaClO(aq)) o xidizing and absorbing gaseous elemental mercury (Hg0(g)) and nitrogen oxides (NOx(g)) were examined. First, some chemical thermodynamic parameters for NaClO(aq) removing Hg0(g) and NOx(g) were calculated, including the standard Gibbs free energy change ΔGθ, standard equilibrium constant Kθ, standard enthalpy change ΔHθ, to theoretically prove the possibility for NaClO(aq) removing Hg0(g) and NOx(g). Next, the idea fo r NaClO(aq) simultaneously removing Hg0(g) and NOx(g) was propounded. And a technical scheme fo r simultaneously removing Hg0(g) and NOx(g) in flue gas was designed. Then, to check the feasibility of this technical scheme, an experiment for NaClO(aq) removing Hg0(g) and NOx(g) was carried out, a mass transfer model based on bubbling reactors for calculating overall mass transfer coefficient was established, the effects of NaClO(aq) concentration, NaClO(aq) temperature, NaClO(aq) pH on Hg0(g) and NOx(g) removal efficiencies and their mass transfer processes were investigated, Hg0(g) and NOx(g) removal processes and mechanisms were analyzed. © 2015 The Japan Society of Mechanical Engineers.

关键词： Mass transfer