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Prediction of flow boiling heat transfer coefficient in horizontal channels varying from conventional to small-diameter scales by genetic neural network

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NUCLEAR engineering AND TECHNOLOGY 2019年第8期51卷 1897-1904页

作者： Zhang, Jing Ma, Yichao Wang, Mingjun Zhang, Dalin Qiu, Suizheng Tian, Wenxi Su, Guanghui Xi An Jiao Tong Univ Shaanxi Key Lab Adv Nucl Energy & Technol Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Dept Nucl Sci & Technol State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Three-layer back propagation network (BPN) and genetic neural network (GNN) were developed in this study to predict the flow boiling heat transfer coefficient (HTC) in conventional and small-diameter channels. The GNN has higher precision than BPN (with root mean square errors of 17.16% and 20.50%, respectively) and other correlations. The inputs include vapor quality x, mass flux G, heat flux q, diameter D and physical parameter phi, and the predicted flow boiling HTC is set as the outputs. Influences of input parameters on the flow boiling HTC are discussed based on the trained GNN: nucleate boiling promoted by a larger saturated pressure, a larger heat flux and a smaller diameter is dominant in small channels;convective boiling improved by a larger mass flux and a larger vapor quality is more significant in conventional channels. The HTC increases with pressure both in conventional and small channels. The HTC in conventional channels rises when mass flux increases but remains almost unaffected in small channels. A larger heat flux leads to the HTC growth in small channels and an increase of HTC was observed in conventional channels at a higher vapor quality. HTC increases inversely with diameter before dry out. (C) 2019 Korean Nuclear Society, Published by Elsevier Korea LLC.

关键词： Back propagation network (BPN) Genetic neural network (GNN) flow boiling heat transfer coefficient Conventional channel Small channel

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Control and thermal analysis for SCWR startup

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ANNALS OF NUCLEAR ENERGY 2019年 134卷 27-37页

作者： Yuan, Yuan Shan, Jianqiang Wang, Li Zhang, Xiaoying Sun Yat Sen Univ Sino French Inst Nucl Engn & Technol Zhuhai Guangdong Peoples R China Xi An Jiao Tong Univ Sch Nucl Sci & Technol State Key Lab Multiphase Flow Power Engn Xian Shaanxi Peoples R China

Startup system, the design of startup sequences analysis is an important part of SCWR design. A thermal hydraulic system analysis code for supercritical water reactor named SCTRAN is used to model the entire startup system based on the circulation loop for startup and once-through direct cycle. The problem of the heat transfer coefficient (HTC) does not accurately capture deterioration phenomenon, the HTC is calculated as a discontinuity in the mode transfer region, its low prediction accuracy above the quasi-critical region have been solved by the new wall heat transfer model. Especially, the look-up table would not be used to obtain the HTC and achieves high prediction accuracy across the critical region, unless the pressure is higher than 19 MPa. After that, to get a smooth recirculation variable pressure startup process, the system model integrates the control system which can controls the temperature, the steam drum water level, the thermal power, and the coolant flow rate. Based on the CSR1000 core and entire once-through direct cycle and circulation loop for startup, four stages under control systems, from low pressure to full power condition in recirculation startup process, were analyzed with code SCTRAN and wall heat transfer model was modified. The calculation results show that the recirculation system can startup from subcritical state to full power state without issue of CHF. The control system can control the parameters quite well and maximum cladding temperature (MCST) can be limited under 650 degrees C in the startup process. The modified SCTRAN code in this paper can further expand the computational range and computational accuracy. The full-scale control system can meet the needs of parameters expected response. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Supercritical water reactor Code development Control system Recirculation pressure startup

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In situ electrochemical synthesis of graphene-poly(arginine) composite for p-nitrophenol monitoring

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JOURNAL OF HAZARDOUS MATERIALS 2022年 421卷 126718-126718页

作者： Li, Yiwei Ma, Yaohong Lichtfouse, Eric Song, Jin Gong, Rui Zhang, Jinheng Wang, Shuo Xiao, Leilei Qilu Univ Technol Biol Inst Shandong Acad Sci Jinan 250103 Peoples R China Shandong Prov Key Lab Biosensors Jinan 250103 Peoples R China Chinese Acad Sci Yantai Inst Coastal Zone Res Key Lab Coastal Biol & Biol Resources Utilizat Yantai 264003 Peoples R China Chinese Acad Sci Yantai Inst Coastal Zone Res CAS Key Lab Coastal Environm Proc & Ecol Remediat Yantai 264003 Peoples R China Aix Marseille Univ CNRS IRD INRAColl FranceCEREGE Ave Louis Philibert F-13100 Aix En Provence France Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Chinese Acad Sci CAS Ctr Excellence Biomacromol Inst Biophys Natl Lab Biomacromol 15 Datun Rd Beijing 100101 Peoples R China

Para-Nitrophenol (p-nitrophenol) is a common industrial pollutant occurring widely in water bodies, yet actual monitoring methods are limited. Herein we proposed a fully electrochemically in situ synthesized graphenepolyarginine composite functionalized screen printed electrode, as a novel p-nitrophenol sensing platform. The electrode was characterized by morphologic, spectrometric and electrochemical techniques. p-nitrophenol in both pure aqueous solution and real water samples was tested. Results show a detection limit as low as the nanomolar level, and display a linear response and high selectivity in the range of 0.5-1250 mu M. Molecular simulation reveals a detailed synergy between graphene and poly-arginine. The preferable orientation of nitrophenol molecules on the graphene interface in the presence of poly-arginine induces H- and ionic binding. This sensor is an ideal prototype for p-nitrophenol quantification in real waters.

关键词： P-nitrophenol Graphene Poly-arginine Electrochemical analysis Wastewater monitoring

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Isolation of a highly efficient phenol-degrading fungus and the preparation of an effective microbial inoculum for activated sludge and its enhancement for hydrogen production

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2019年第30期44卷 16004-16014页

作者： Wang, Xueqing Wang, Ye Zhang, Anlong Duo, Chen Zhao, Chengxin Xie, Fei Shaanxi Univ Sci & Technol Coll Bioresources Chem & Mat Engn Coll Environm Sci & Engn Xian 710021 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

A phenol-degrading fungal strain Magnusiomyces capitatus QWD1 was isolated from activated sludge that was used to treat papermaking wastewater. Through parameters optimization, the optimal degradation conditions were found to encompass (NH4)(2)SO4 as nitrogen source (14 mmol/L), inoculum concentration of 15%, pH 7 and a temperature of 35 degrees C. Four different materials were used as carriers for the preparation of the microbial inoculum and the effect of storage temperatures on inoculum viability was investigated. With the prepared bioaugmentation inoculum addition to activated sludge, it was found to markedly increase the original system's treatment efficiency of phenol-containing wastewater. A high-throughput sequencing-based analyze approach revealed that the phenol-degrading inoculum addition can increase the abundance and diversity of fungi in the treatment system, which supports the development of a stable microbial ecosystem. The H-2 production of photosynthetic bacteria with the bioaugmented QWD1 inoculum was 32.4% higher than the control without inoculum addition when using the phenol-containing wastewater. (C) 2018 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.

关键词： Phenol degradation Fungi Microbial inoculum Activated sludge Hydrogen production

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BiVO4 charge transfer control by a water-insoluble iron complex for solar water oxidation

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APPLIED CATALYSIS A-GENERAL 2023年 652卷

作者： Benko, Timea Shen, Shaohua Nemeth, Miklos Su, Jinzhan Szamosvolgyi, Akos Kovacs, Zoltan Safran, Gyorgy Al-Zuraiji, Sahir M. Horvath, Endre Zsolt Sapi, Andras Konya, Zoltan Pap, Jozsef Sandor Ctr Energy Res Surface Chem & Catalys Dept Konkoly Thege ut 29-33 H-1121 Budapest Hungary Xi An Jiao Tong Univ Int Res Ctr Renewable Energy IRCRE State Key Lab Multiphase Flow Power Engn MFPE Xian 710049 Shaanxi Peoples R China Univ Szeged Interdisciplinary Excellence Ctr Dept Appl & Environm Chem Rerrich Bela ter 1 H-6720 Szeged Hungary Inst Tech Phys & Mat Sci Ctr Energy Res Konkoly Thege ut 29-33 H-1121 Budapest Hungary Ctr Energy Res CER KFKI CampusKonkoly Thege Mikl ut 29-33 H-1121 Budapest Hungary

Photoelectrochemical water splitting can become efficient by grafting co-catalysts on semiconductors that improve the interfacial oxygen evolution reaction. We applied a simple non-noble metal pre-catalyst, [FeII(PBI)(3)](2+) (PBI is 2-(2'-pyridyl)benzimidazole ligand) for this purpose on a nanopyramidal BiVO4 semiconductor that was morphologically optimal for efficient light harvesting, but its performance suffered from Vpoor surface recombination sites. The [FeII(PBI)(3)](2+) in situ transformed to a-Fe2O3 nanoparticles on V-vacant areas of BiVO4 mending their photocurrent-limiting effect. Photoelectrochemistry at pH 8.2 confirmed that the a-Fe2O3 co-catalyst improved the charge transfer efficiency by an order of magnitude, suppressed the recombination in the bulk and reduced the charge transfer resistance. Overall, the a-Fe(2)O(3 )suppressed the recombination on the V-poor surface, while at high potentials it provided high-valent centers for the oxygen evolution. The resulting photocurrent density far exceeding that of BiVO4 or samples modified by FeCl3 or Fe(NO3)3 underlines the metallochaperone-like effect of the PBI ligand.

关键词： Fe-complex BiVO4 semiconductor Solar water splitting Photoelectrochemical water oxidation

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Effect of Swirl on Gasification Characteristics in an Entrained-flow Coal Gasifier

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INTERNATIONAL JOURNAL OF CHEMICAL REACTOR engineering 2020年第3期18卷

作者： Li, Rongbin Xie, Mingzhuang Jin, Hui Guo, Liejin Liu, Fengqin Univ Sci & Technol Beijing Sch Met & Ecol Engn Beijing 100083 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

The three-dimensional (3-D) comprehensive mathematical model was developed to simulate the coal gasification process in an entrained flow gasifier with a swirl burner. The models employed or developed includes the coal devolatilization model, the char combustion and gasification model, the gas homogeneous reaction model, the random-trajectory model, gas turbulence model, and the P-1 radiation model. The solution of models was executed based on the computational fluid dynamics (CFD). By qualitatively comparing the results at different swirl number, the significant influences of swirl on characteristics of coal gasification such as flow distributions, gas temperature and product composition including hydrogen (H-2), carbon monoxide (CO), etc., and on the performance of coal gasification such as averaged exit product composition, carbon conversion rate and cold gas efficiency, were in detail discussed. Especially, a proper swirl number (S <= 0.65) in favor of gasification was found for the investigated gasifier in this paper.

关键词： swirl coal gasification CFD entrained flow

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A fully coupled model of hydrodynamic -chemical -electrochemical processes for CO 2 uniform corrosion in multi -physics environment

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JOURNAL OF PETROLEUM SCIENCE AND engineering 2020年 193卷 107436-107436页

作者： Wang, Kai Li, Chenpei Li, Yanhui Lu, Jinling Wang, Yueshe Luo, Xingqi Xian Univ Technol State Key Lab Ecohydraul Northwest Arid Reg 5 Jinhua South Rd Xian 710048 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn 28 Xianning West Rd Xian 710049 Peoples R China

Carbon dioxide uniform corrosion occurs widely in the petroleum industry and threatens the safe production and transportation of petroleum resources. It is a complex issue involving a variety of physical, chemical and elec- trochemical processes in multiple temporal and spatial scales. A fully coupled model, taking into account all involved processes in a coupled fashion, such as fluid flow, multi -ion transport, multi -component chemical/ electrochemical reactions, is established to comprehensively investigate the mechanism of CO 2 corrosion in multi -physics environment. The reliability of this model is validated by the good consistency between the pre- dicted corrosion rates and the experimental results in the literature, and this model performs better in corrosion rate prediction than the previous models due to the explicit solution for the convective mass transfer. Based on this fully coupled model, the corrosion mechanism in the multi -physics coupled environments is revealed in terms of the time -dependent ion concentration field, mass transfer and electrode reaction kinetics. The inter- relationship between the corrosion kinetics and the flow effect is explored. The results indicate that the time - dependent corrosion behavior is determined by the combined effect of the solution chemistry and electrical field. By accelerating the mass transport of corrosive species and the involved multi -component reactions, the fluid flow can significantly promote the corrosion process, while the promotion effect weakens gradually at higher flow velocities. Additionally, the flow effect at lower pH values is much more pronounced due to the transformation of the predominant controlling factors for electrode kinetics.

关键词： CO 2 uniform corrosion Multi-physics model flow effect Multi-ion transport Multi-component reactions

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Quantifying the sources of synergistic effects in co-pyrolysis of pinewood and polystyrene

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APPLIED ENERGY 2021年 302卷 117562-117562页

作者： Burra, Kiran Raj G. Liu, Xuan Wang, Zhiwei Li, Jinhu Che, Defu Gupta, Ashwani K. Univ Maryland Dept Mech Engn Combust Lab College Pk MD 20742 USA Hunan Univ Coll Environm Sci & Engn Key Lab Environm Biol & Pollut Control Minist Educ Changsha 410082 Hunan Peoples R China Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Henan Univ Technol Coll Environm Engn Zhengzhou 450001 Peoples R China Anhui Univ Sci & Technol Coll Safety & Engn Huainan 232001 Peoples R China

Co-processing of biomass and plastic wastes via pyrolysis and gasification for feed-flexibility revealed the presence of synergistic enhancement of H-2 and syngas yield and lowering of char and tar yields. However, an understanding of the source of these interactions and their quantification is lacking. To address this, we investigated the co-pyrolysis of pinewood (PW) and polystyrene (PS) blends at 900 degrees C using uniquely arranged sample-loading configurations in a fixed-bed reactor with online product gas and energy consumption analysis. Quantification of interactions such as volatiles-volatiles, volatiles-feedstock, and volatiles-char interactions in comparison with weighted results from individual pyrolysis of PW and PS provided deconvoluted information on the synergistic effects. Volatiles-volatiles interaction accounted for a 33% increase in H-2, while PS volatiles-PW intermediates interaction accounted for 17% increase, and inhibitive PW volatiles-PS intermediates interaction led to 8% decrease. This deconvolution also revealed another 20% increase associated with the evenly mixed copyrolysis of PW and PS that was not accounted for from the volatiles-feedstocks interaction. The co-pyrolysis of PS with PW char also revealed the catalytic activity of PW char on plastics decomposition which was found to be restricted by the capacity of PS melt to block the char's active sites during their direct contact. Cracking of PS volatiles on these catalytic active sites led to the increased yields of CH4 and H-2. These results provide quantified insight into the sources of interaction between biomass and plastics to enhance synergy, develop component compatibility, and gain prediction capability for sustainable and feed-flexible gasifier development.

关键词： Co-pyrolysis Polystyrene Synergistic effects Volatiles interaction Catalytic char Feed-flexible

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Unsynchronized motion of inner and outer membranes of compound capsules in shear flow

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PHYSICS OF FLUIDS 2020年第12期32卷 127115-127115页

作者： Xu, Han Bai, Bo Feng Xi An Jiao Tong Univ Dept Bldg Environm & Energy Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

Despite its significance in understanding behaviors of biological cells with nucleus or designing functions of complex artificial capsules in applications, the dynamics of elastic capsules enclosing complicated internal structures in flow is still largely unexplored. In this study, by using our own three-dimensional front-tracking finite-difference model, we present a numerical investigation into the dynamics of a compound capsule in a simple shear flow whose inner and outer membranes have the same prolate ellipsoidal shape at the rest state. Particular interest is focused on the unsynchronized motion of the inner and outer membranes. Regarding the dynamical regime, both the inner and outer capsules can undergo either synchronized or unsynchronized dynamical regimes (i.e., swinging or tumbling), which strongly depends on the inner-to-outer capillary number ratio Ca-in/Ca-out, the inner-to-outer volume ratio phi, and the prolate aspect ratio a/b. Particularly, via establishing a phase diagram based on a/b and phi at Ca-in/Ca-out = 1, we find that the inner and outer membranes can exist simultaneously in different dynamical regimes, even if they have the same deformability and the same shape. More importantly, if the detailed oscillation behavior is also concerned besides the capsule's dynamical regime, such as the transient shape and the oscillating period, unsynchronization is always obvious between the inner and outer capsules. Specifically, the inner capsule exhibits a slower oscillation than the outer capsule no matter if they lie in the swinging or tumbling regime.

关键词： Shear flow

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Performance of V-Cone flowmeter applied to cryogenic fluid measurement considering cavitation 29

Performance of V-Cone flowmeter applied to cryogenic fluid m...

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29th IAHR Symposium on Hydraulic Machinery and Systems (IAHR)

作者： He, Denghui Bai, Bofeng Chen, Senlin Zhang, Jie Guo, Pengcheng Xian Univ Technol State Key Lab Ecohydraul Northwest Arid Reg Xian 710048 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

The V-Cone flowmeter is a promising differential pressure flowmeter for metering the cryogenic fluid for its many advantages. When the cryogen velocity increases to a certain value, the cavitation may occur in flowmeter, which may significantly affect the performance of V-Cone flowmeter. However, the effect of cavitation on performance of V-Cone flowmeter remains unclear and there are no published studies to our knowledge on this issue. Here we investigate the performance of V-Cone flowmeter when measuring the cryogenic fluids, especially the effects of cavitation on the discharge coefficient and pressure loss coefficient of the flowmeter. Two cryogenic fluids are investigated, including liquid nitrogen (LN2) and liquid hydrogen (LH2). For comparison, the water is also investigated. The realizable kappa-epsilon model is used to describe the turbulence. The Schnerr-Sauer cavitation model is used to investigate the effect of cavitation on the performance of the V-Cone flowmeter. The results show that there was little effect of cavitation on the discharge coefficient and pressure loss coefficient at the initial stage of cavitation. When the cloud cavitation occurred downstream of V-Cone, the discharge coefficient decreases rapidly with Reynolds number increasing, while the pressure loss coefficient rises quickly. The average discharge coefficient is almost the same for different fluids in the stable region;while the cryogenic fluids have wider stable Reynolds number ranges than the water. The lower limits of the Reynolds number for the constant discharge coefficient is very close for three fluids, however, for the upper limits of Reynolds number are quite different. We conclude that measurement range of the cryogenic fluid is much larger than that of the water, which shows that the V-Cone flowmeter exhibits great potential in the measurement of cryogenic fluid. This study provides insights into the effect of cavitation on the measurement of V-Cone flowmeter and opens a

关键词： Cavitation

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