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Preliminary design and CFD analysis of a radial inflow turbine and the turbine seal for an organic Rankine cycle using zeotropic mixture

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ENERGY CONVERSION AND MANAGEMENT 2020年第0期209卷 112647-000页

作者： Xia, Jiaxi Zhou, Kehan Guo, Yumin Wang, Jiangfeng Lou, Juwei Dai, Yiping Xi An Jiao Tong Univ Inst Turbomachinery Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Sci & Technol Reactor Syst Design Technol Lab Chengdu 610041 Peoples R China

Zeotropic mixtures exhibit great potential for further investigation of organic Rankine cycle (ORC) in the field of low temperature heat utilization because of the characteristics of varying temperature evaporation in two-phase region. However, few studies are contributed to the design of zeotropic mixture turbine and turbine seal. In this paper, the system optimization of ORC by means of genetic algorithm is conducted for different mixtures to obtain the optimal mixture working fluid and initial design parameters of turbine. The thermal design of the mixture ORC radial inflow turbine is carried out, and the CFD simulation is performed to investigate the threedimensional flow characteristic of the designed turbine. Meanwhile, the helical groove seal of the turbine shaft is designed and analyzed through CFD method. Results show that the mixture ORC radial inflow turbine is well designed with an isentropic efficiency of 83.71%, and CFD results basically match with the thermal design results. What's more, the CFD simulation result for the differential pressure of the helical groove seal has an only -5.83% deviation compared with the designed one, and the helical groove seal is well designed with desirable sealing performance.

关键词： Organic Rankine cycle Zeotropic mixtures Radial inflow turbine Helical groove seal CFD analysis

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Modulating the Electronic Metal-Support Interactions in Single-Atom Pt1-CuO Catalyst for Boosting Acetone Oxidation

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ANGEWANDTE CHEMIE-INTERNATIONAL EDITION 2022年第28期61卷 e202200763-e202200763页

作者： Jiang, Zeyu Tian, Mingjiao Jing, Meizan Chai, Shouning Jian, Yanfei Chen, Changwei Douthwait, Mark Zhen, Lirong Ma, Mudi Song, Weiyu Liu, Jian Yu, Jiaguo He, Chi Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Natl Univ Singapore Dept Chem Singapore 117543 Singapore China Univ Geosci Fac Mat Sci & Chem Lab Solar Fuel Wuhan 430074 Peoples R China China Univ Petr State Key Lab Heavy Oil Proc Beijing 102249 Peoples R China Cardiff Univ Max Planck Cardiff Ctr Fundamentals Heterogeneous Sch Chem Cardiff CF10 3AT Wales Chinese Acad Sci Inst High Energy Phys Beijing 100049 Peoples R China Univ Chinese Acad Sci Natl Engn Lab VOCs Pollut Control Mat & Technol Beijing 101408 Peoples R China

The development of highly active single-atom catalysts (SACs) and identifying their intrinsic active sites in oxidizing industrial hazardous hydrocarbons are challenging prospects. Tuning the electronic metal-support interactions (EMSIs) is valid for modulating the catalytic performance of SACs. We propose that the modulation of the EMSIs in a Pt-1-CuO SAC significantly promotes the activity of the catalyst in acetone oxidation. The EMSIs promote charge redistribution through the unified Pt-O-Cu moieties, which modulates the d-band structure of atomic Pt sites, and strengthens the adsorption and activation of reactants. The positively charged Pt atoms are superior for activating acetone at low temperatures, and the stretched Cu-O bonds facilitate the activation of lattice oxygen atoms to participate in subsequent oxidation. We believe that this work will guide researchers to engineer efficient SACs for application in hydrocarbon oxidation reactions.

关键词： Acetone Oxidation Electronic Metal-Support Interactions Intrinsic Mechanism Single-Atom Catalysts

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Numerical Study on the Thermal Hydraulic Characteristics in a Wire-Wrapped Assembly of LFRs

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FRONTIERS IN ENERGY RESEARCH 2020年 8卷

作者： Li, Jun Fang, Di Guo, Chao Wang, Mingjun Deng, Jian Tian, Wenxi Qiu, Suizheng Su, G. H. Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Shaanxi Key Lab Adv Nucl Energy & Technol SchNucl Sci & Technol Xian Peoples R China Nucl Power Inst China Sci & Technol Reactor Syst Design Technol Lab Chengdu Peoples R China

The concept of wire-wrapped assembly has been widely adopted in liquid metal-cooled reactors to enhance the capability of flow and heat transfer. The detailed 3D thermal hydraulic behaviors of liquid metal in the wire-wrapped assembly directly affect the safety of the reactor. In the present work, a numerical study on a 19-pin wire-wrapped assembly cooled by a lead-bismuth eutectic was carried out using the CFD method. The geometrical model is referred to in the test section in KIT's 19-pin experiments, which is a scaled test assembly based on the MYRRHA reactor. The established CFD model was validated against experimental data and results showed that the SST k-omega model accompanied with the modified Pr-t was appropriate for the current problem. Then the numerical models were extensively used in the modeling of the blocked assembly flow with a cylindrical blockage. Also, the influences of blockage longitude, position, and porosity on the thermal hydraulic characteristics in the assembly were evaluated in detail. This work is meaningful for the deep understanding of safety features under the condition of assembly blockage operation in LFRs.

关键词： CFD sub-channel blockage fuel assembly lead-bismuth eutectic wire-wrapped assembly

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Numerical study on the turbulent mixing in channel with Large Eddy Simulation (LES) using spectral element method

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NUCLEAR engineering AND DESIGN 2019年第Jul.期348卷 169-176页

作者： Ju, Haoran Wang, Mingjun Chen, Chong Zhao, Xiaohan Zhao, Minfu Tian, Wenxi Su, G. H. Qiu, Suizheng Xi An Jiao Tong Univ Sch Nucl Sci & Technol State Key Lab Multiphase Flow Power Engn Xian 710049 Shanxi Peoples R China China Inst Atom Energy POB 275-59 Beijing 102413 Peoples R China

Turbulent mixing is an important thermal hydraulic phenomenon in the reactor core rod bundles and it leads to strong momentum and energy transfer among adjacent subchannels in fuel assembly. Generally, turbulent mixing coefficient is usually referred to describe turbulent effect, which commonly sets to a constant or calculated utilizing Reynolds number dependent fitting correlations based on experimental data. In this paper, a high-scalable and high-performance spectral element method combining with high passed filtered Large Eddy Simulation (LES) model has been proposed to simulate the turbulent flow through parallel wall channel and square channel with a cylindrical rod for single-phase flow. In the parallel wall channel case, mesh sensitivity analysis and model validation were accomplished by comparing the simulation data with DNS references utilizing key parameters such as velocity profile and stresses in the near wall region. Meanwhile, for the square channel with a cylindrical rod case, instantaneous lateral velocity monitored in the gap center has been compared with the experimental data with different Reynolds numbers and geometric conditions. From the simulation approach, both the absolute oscillation amplitude and the oscillation frequency increase with the pitch diameter ratio. Finally, the simulation results of turbulent mixing coefficient dependent on Reynolds number were validated with both experimental and theoretic references to demonstrate the feasibility of spectral element method combining with LES model. The root mean square (RMS) value of lateral fluctuating velocity was adopted to reflect the effective mixing capability, predicting the turbulent mixing phenomena with a reasonable degree of accuracy from the specific calculation strategy. Fast Fourier Transform (FFT) also performed and got an agreement with reference data.

关键词： Turbulent mixing LES Spectral element method CFD validation

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Metabolically versatile Rhodobacter sphaeroides as a robust biocatalyst for H2 production from lignocellulose-derived mix substrates

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FUEL 2021年 302卷 121108-121108页

作者： Hu, Jun Wei, Wenwen Li, Qing Cao, Wen Zhang, Anlong Wang, Xueqing Ni, Yonghao Guo, Liejin Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Shaanxi Univ Sci & Technol Coll Bioresources Chem & Mat Engn Xian 710021 Peoples R China Univ New Brunswick Dept Chem Engn Fredericton NB E3B 5A3 Canada

Biological hydrogen production has received much attention and it is of practical interest to produce H2 biologically using low-cost lignocellulose-derived mix substrates, usually containing various compounds, such as arabinose, formate, acetate, furfural, HMF, in addition to glucose and xylose. Herein, we systematically evaluated impacts of single/mixed model compounds, and energy sorghum hydrolysate on H2 production by Rhodobacter sphaeroides. We found (i) obvious cell growth was observed for all single substrates including formate, furfural and HMF, which for the first time, were reported in R. sphaeroides;(ii) cultures pairing acetate with a mixture of glucose and xylose remarkably improved H2 production compared to that without acetate;(iii) arabinose/ formate had limited effects on the mixed-sugar photo-fermentation;(iv) furfural/HMF degradation was expedited by co-utilization with glucose and xylose. The results support the conclusion that photo-fermentation with hydrolysate achieved comparable, or even advantageous H2 production over that of model compound mixtures. Metabolic diversity in R. sphaeroides enables the well-performed degradation of complex substrates for biofuel production.

关键词： Lignocellulose Rhodobacter sphaeroides Mixed-substrate utilization H2 production Metabolic diversity

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Light to enhance CO₂ capture by a flexible heterostructure

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CHEMICAL engineering AND PROCESSING-PROCESS INTENSIFICATION 2021年 159卷 108210-108210页

作者： Yu, Yunsong Zhang, Chen Sharif, Maimoona Zhang, Zaoxiao Wei, Jinjia Wang, Geoff G. X. Xi An Jiao Tong Univ Sch Chem Engn & Technol 28 Xianning West Rd Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn 28 Xianning West Rd Xian 710049 Peoples R China Univ Queensland Sch Chem Engn St Lucia Qld 4072 Australia

Based on photovoltaic effect and annealing,a flexible liquid-solid heterostructure of PANI and PyBIG based on carbon nano-tube (CNT) is prepared to drive the low temperature (343 K-363 K) CO2 desorption intensified by the light. By the DFT and experiment, the reaction mechanism is determined as electron and hole produced by the light, deprotonization, electron and hole transport, and CO2 release. The flexible characteristic of the heterostructure is identified as interface slip, transport channel change and stretching phenomenon in the nanoscale. The repelling effect between water molecule and oil molecule enhances the COO-H bond breaking and NH2 production. The stretching phenomenon makes the electron and hole transport along the line rather than in a circle. The CO2 desorption reaction energy is determined as low as 11.42 kJ/mol. The energy consumption of heterostructure to drive the CO2 desorption at 343 K-363 K is determined as 0.89 GJ/t-1.12 GJ/t, which is much lower than the conventional 2.2 GJ/t-2.8 GJ/t.

关键词： Energy consumption Heterostructure Carbon dioxide Sunlight Annealing

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Understanding Platinum Ionomer Interface Properties of Polymer Electrolyte Fuel Cells

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JOURNAL OF THE ELECTROCHEMICAL SOCIETY 2022年第6期169卷 064512-064512页

作者： Qi, Yongzhen Morimoto, Yu Shibata, Masao Suzuki Gao, Ziliang Sabarirajan, Dinesh C. Haug, Andrew T. Zenyuk, Iryna, V Univ Calif Irvine Dept Mech & Aerosp Engn Irvine CA 92717 USA Univ Calif Irvine Adv Power & Energy Program Irvine CA 92717 USA Univ Calif Irvine Dept Chem & Biomol Engn Irvine CA 92717 USA Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Int Res Ctr Renewable Energy Xian 710049 Shaanxi Peoples R China Tufts Univ Dept Mech Engn Medford MA 02155 USA 3M Co 3M Ctr St Paul MN USA

A well-designed cathode catalyst layer with optimal ionomer distribution is critical to minimizing amount of Platinum (Pt) content in polymer electrolyte fuel cells (PEFCs). The impact of Pt loading, ionomer content and carbon support types on the catalyst/ ionomer interface were also investigated at dry and wet conditions. Higher Pt loadings resulted in higher double layer capacity (C-dl) and similar electrochemical surface area (ECSA) due to well dispersed ionic phase material. Higher ionomer content resulted in higher ionic conductivity but also showed similar SO3- group coverage. High surface area (HSA) carbon support had larger ECSA and C(dl )at both dry and wet conditions, as less agglomerated Pt was well dispersed in the meso-pores of the support. Lower SO3- group coverages were observed for HSA carbon than for Vulcan carbon due to Pt particles being buried within the porous HSA carbon support. The effect of cell conditioning and voltage recovery on the PEFC cathode catalyst layer was shown to have minimal impact on SOT group coverage despite a decrease in Cap and ECSA due to the size increase of Pt particles. At dry condition, a significant increases in SO3- group coverage were observed for all MEAs due to higher adsorptivity of ionomer in dry conditions. (C) 2022 The Author(s). Published on behalf of The Electrochemical Society by IOP Publishing Limited.

关键词： Ionomers

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Investigation of fuel volatility on the heat transfer dynamics on piston surface due to the pulsed spray impingement

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INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 2021年 170卷 121008-121008页

作者： Zhou, Zhi-Fu Liang, Lin Murad, Safwan Hanis Mohd Camm, Joseph Davy, Martin Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Univ Oxford Dept Engn Sci Oxford OX1 3PJ England Canterbury Christ Church Univ Sch Engn Technol & Design Canterbury CT1 1QU Kent England

The fuel spray in a gasoline direct injection (GDI) engine can impinge on the piston surface to form a liquid film, which leads to a decrease of the combustion efficiency and the increase of particulate emissions. The dynamic heat transfer process resulting from the impingement has an important effect on the evaporation of the liquid film and its residence time. In this study, two pure component fuels (methanol and n-pentane), and three fuel blends with different initial boiling points and enthalpies of vaporization marked as Fuel B, Fuel C and Fuel D, are designed to investigate the effect of the fuel volatility on heat transfer dynamics of pulsed spray impingement with different: injection temperatures (T-inj), injection pressures (P-inj), piston temperatures (T-pis) and injection distances (D-inj). The results show that the spray a transient heat transfer induced by different fuel sprays are very sensitive to changes of T-i(nj) and D-inj, and also depend on their boiling points and enthalpies of vaporization. The impinging and cooling intensities are greatly reduced when the pressure ratio of ambient pressure to saturation pressure (P-a/P-sat) decreases, as a result of increasing T-inj The maximum surface temperature drop (Delta T-s, (max)) and peak heat flux (q(max)) on the impinging surface are reduced greatly by over 60% for fuels with low enthalpy of vaporization such as n-pentane, Fuel B, Fuel C and Fuel D, while they are only reduced by less than 15% for methanol with highest enthalpy of vaporization when T-inj increases from 25 degrees C to 140 degrees C. Exponential equations are proposed to describe the relationship between q(max) and P-a/P-sat. When D-inj increases from 50 mm to 70 mm, q(max) is reduced by over 10% for fuels such as n-pentane, methanol, Fuel B and Fuel C with low initial boiling points, whereas q(max) is increased slightly by 7% for Fuel D with the highest boiling point. On the other hand, the transient heat transfer of different fuels

关键词： Spray impingement Fuel volatility Transient heat transfer GDI engine Flash boiling

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Towards enhanced catalytic reactivity in CO2-assisted gasification of polypropylene

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FUEL 2021年 284卷 119076-119076页

作者： Wang, Zhiwei Liu, Xuan Burra, Kiran G. Li, Jinhu Zhang, Mengju Lei, Tingzhou Gupta, Ashwani K. Univ Maryland Dept Mech Engn Combust Lab College Pk MD 20742 USA Energy Res Inst Co Ltd Henan Acad Sci Zhengzhou 450008 Peoples R China Henan Key Lab Biomass Energy Zhengzhou 450008 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Sch Energy & Power Engn Xian 710049 Peoples R China China Univ Min & Technol Sch Safety Engn Xuzhou 221116 Jiangsu Peoples R China

The role of catalyst (Ni/Al2O3) position on improved gasification of polypropylene (PP) in CO2 atmosphere using a fixed bed reactor at 900 degrees C was examined and the results compared with non-catalytic gasification. The catalytic gasification included in-situ and quasi-in-situ (with feedstock located close to but not directly in contact with the catalyst) configuration. Results are reported on the evolutionary behavior and yield of carbon monoxide (CO), hydrogen (H-2), hydrocarbons (CmHn) and total syngas. Compared to non-catalytic gasification, in-situ, and quasi-in-situ catalytic gasification produced higher H-2 by 120.5% and 137.1%, higher CO by 38.2% and 24.0%, higher CmHn by 57.1% and 98.2%, and higher total syngas by 44.1% and 43.8%, respectively. CO2-assisted gasification of PP with Ni/Al2O3 catalyst significantly enhanced the gases evolution rate and improved the syngas yield. Results revealed better catalytic activity with quasi-in-situ configuration in the thermal decomposition of PP into H-2 and CmHn than in-situ catalytic configuration. However, in-situ catalytic configuration provided more CO under similar gasification conditions. Approximately 0.8, 1.1 and 1.0 kg of CO2 could be consumed per kg of PP feedstock to generate syngas energy yield of 27.5, 43.1 and 48.1 MJ with non-catalytic, in-situ and quasi-in-situ catalytic configuration, respectively, suggesting efficient utilization of both CO2 and PP waste for clean and efficient energy production.

关键词： CO2-assisted gasification Polypropylene (PP) In-situ catalytic Quasi-in-situ catalytic Syngas evolution

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Numerical approach to study the thermal-hydraulic characteristics of Reactor Vessel Cooling system in sodium-cooled fast reactors

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PROGRESS IN NUCLEAR ENERGY 2019年 110卷 213-223页

作者： Song, Ping Zhang, Dalin Feng, Tangtao Wang, Shibao Chen, Jing Wang, Xin'an Xue, Xiuli Zhang, Yapei Wang, Mingjun Qiu, Suizheng Su, G. H. Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Sch Nucl Sci & Technol 28 Xianning West Rd Xian 710049 Shaanxi Peoples R China China Inst Atom Energy Beijing Peoples R China

The main vessel plays an important role in containing the entire primary sodium for pool-type sodium-cooled fast reactors (SFRs). The Reactor Vessel Cooling System (RVCS) has great effect on cooling the main vessel. However, little attention has been given to the study on transient characteristics of RVCS in the previous SFR research. Thus, a home-made one-dimensional (1-D) code named Reactor Vessel Cooling system Analysis Code for Sodium-cooled fast reactor (VEGAS) is proposed to evaluate the thermal-hydraulic characteristics for SFR. The detailed models of the developed VECAS are presented in this paper. Moreover, the developed models have been validated against an experimental study. Numerical data of the main vessel cooling circuit are compared with the measurements of the Demonstration Fast Breeder Reactor (DFBR). The simulation results are in good agreement with the experimental data. Furthermore, the validated VECAS is coupled with the Transient Thermal-Hydraulic Analysis Code for Sodium-cooled fast reactors (THACS). The transient characteristics of RVCS in China Experimental sodium-cooled Fast Reactor (CEFR) are simulated by the coupled code. Steady analysis shows that the main vessel is cooled effectively. The peak temperature appears at the top of the main vessel lower than the permissible upper temperature limit. During the transient analysis, VECAS has predicted a reverse flow in RVCS, which contributes to the core cooling. Furthermore, sensitivity analysis of the main parameter has also been performed. Therefore, it can be concluded that coupled VECAS has the ability to evaluate the thermal-hydraulic characteristics as well as the decay heat removal capacity of RVCS. The coupled code could provide references and technical supports for the design and optimization of the pool-type sodium-cooled fast reactor.

关键词： Reactor vessel cooling system Code development Sodium-cooled fast reactor Sensitivity analysis

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