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Experimental Investigation on Ejector Performance Using R134a as Refrigerant

Journal of Thermal Science 2019年第4期28卷 727-735页

作者： DAI Zhengshu YU Bo LIU Pengpeng CHEN Guangming ZHANG Hua School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China State Key Laboratory of Air-conditioning Equipment and System Energy Conservation Zhuhai 519070China Institute of Refrigeration and Cryogenics Zhejiang UniversityHangzhou 310027China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China

Ejector refrigeration has the advantage of low capital cost,simple design,reliable operation,long lifespan and almost no *** only weakness is the low efficiency and its intolerance to deviations from design operation condition.R134 a used in ejector refrigeration system gives better performance in comparison with many other environmental friendly refrigerants as the generation temperature is from 75℃to 80℃.The present work experimentally investigated the on-design and off-design performance of the ejector with fixed geometry using R134 a as refrigerant,and cycle performance of the ejector refrigeration *** experimental prototype was constructed and the effects of primary flow inlet pressure,secondary flow inlet pressure and ejector back pressure on ejector performance and cycle performance were investigated *** operation conditions are:primary flow inlet pressure from 2.2 MPa to 3.25 MPa,secondary flow inlet pressure from 0.36 MPa to 0.51 MPa,ejector back pressure from 0.45 MPa to 0.67 *** were drawn from the experimental results,and the experimental data can be used for validation of theoretical model for both critical and subcritical mode.

关键词： ejector performance refrigeration R134a experiment

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fEffect of alkali and alkaline metals on gas formation behavior and kinetics during pyrolysis of pine wood

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Fuel 2021年 290卷

作者： Li, Jinhu Burra, Kiran G. Wang, Zhiwei Liu, Xuan Gupta, Ashwani K. The Combustion Laboratory Department of Mechanical Engineering University of Maryland College ParkMD20742 United States Faculty of Engineering China University of Geosciences WuhanHubei430074 China College of Environmental Engineering Henan University of Technology Zhengzhou450001 China State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China

This study examines the acid and alkaline treatment of pine wood to help understand the effect of alkali and alkaline earth metals (AAEMs) content on the pyrolysis behavior at different temperatures. Acid and alkali pretreatment of pine wood were conducted to modify AAEMs content by ion-exchanging method. Thermal kinetic behavior of the pretreated samples was first conducted by a thermogravimetric analyzer (TGA) at different heating rates that provided activation energies of pyrolysis. Gas formation behavior of the samples for different extents of conversion was carried out in a fixed-bed reactor at two different temperatures of 823 K and 1073 K. Evolutionary behavior of the gas components during pyrolysis, including flow rate, and yield and their energy content were measured and compared. Results showed that the values of activation energies increased with the extent of conversion for all the pretreated samples examined. The effect of AAEMs on pyrolysis behavior of biomass varied with the extent of conversion. The presence of AAEMs in biomass decreased the decomposition energy at low conversion while it greatly improved under high conversion. Besides, alkali treated sample with higher AAEM content enhanced the gas and char yield while it reduced the bio-oil production at low temperature with low conversion. However, at high temperature the opposite trend was observed. Presence of AAEMs was favorable for the generation of H2, CO, CO2 and CnHm at low temperature, while it showed an inhibition effect on CO and CnHm yield and syngas energy at high temperature. The catalytic mechanism of AAEMs on the pyrolysis behavior at different temperatures was discussed based on activation energy and gaseous formation. Results revealed decomposition of carboxylate at low temperature and formation of stable biomass-Na (BM-Na) structure at high temperature that led to the variation of activation energy and changed gaseous products yield and syngas energy. Acid washing pretreatment wa

关键词： Activation energy

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Experimental Investigation on Critical Heat Flux for Water flowing in a Vertical Uniformly Heated Rifled Tube under Near-critical Pressures

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Journal of Thermal Science 2018年第6期27卷 527-540页

作者： XIE Haiyan YANG Dong ZHAO Yunjie JIANG Huiqing QU Mofeng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

This study experimentally investigated the critical heat flux(CHF) of departure from nucleate boiling(DNB) of water flowing under near-critical pressures in a 2 m-long vertical upward rifled tube with the size of Φ35 × 5.67 mm. Operating conditions included pressures of 18–21 MPa, mass fluxes of 475–1000 kg·m^(-2)·s^(-1), inlet subcooling temperatures of 3–5°C, and wall heat fluxes of 40–960 kW·m^(-2). Tube wall temperature distribution and heat transfer performance in different test conditions were obtained. The effects of the operating parameters on CHF were analyzed. Four heat transfer coefficient correlations were evaluated against our experimental data for further investigation of the two-phase heat transfer characteristics. A heat transfer correlation based on Martinelli number utilized in two-phase region and two empirical correlations used to predict the CHF in rifled tube at near-critical pressures were proposed. Meanwhile, experimental CHF data in rifled tube were compared with six widely used correlations and a CHF look-up table. The CHF enhancement effect in rifled tube is obvious as compared with the CHF data in smooth tube. Results show that DNB occurs at low vapor quality and subcooled region in the rifled tube at near-critical pressures. The increase in pressure leads to the early occurrence of DNB and the decrease in CHF, whereas the increase in mass flux delays the occurrence of DNB and results in the increase in CHF. DNB presents a tendency to move toward the inlet of the rifled tube. At individual operating conditions, DNB and dryout coexist at different sections of the rifled tube.

关键词： critical heat flux near-critical pressure rifled tube DNB heat transfer

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Study of thermophysical properties of binary mixtures of N-phenyl ethanolammonium based protic ionic liquids with water and ethanol solvents

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Journal of Ionic Liquids 2022年第1期2卷

作者： Chennuri, Bharath Kumar Losetty, Venkatramana Sreenivasulu, K. Gardas, Ramesh L. Sivakumar, K. A.P. Tirupati517502 India Department of Chemistry VelTech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology Avadi Chennai600062 India Department of Chemistry State Key Laboratory of Multiphase Flow in Power Engineering Xian Jiaotong University Xian710049 China Department of Chemistry Indian Institute of Technology Madras Chennai600036 India

This work reveals that the physicochemical properties such as density, ρ and speed of sound, u for the binary mixtures of N-phenylethanolammonium formate ([NPEA][For]) and N-phenylethanolammonium acetate ([NPEA][Ace] with water and ethanol solvents were experimentally measured for the temperature ranges from 293.15 K to 318.15 K at atmosphere pressure. The apparent molar volume, VΦ and apparent molar isentropic compressibility, κs,Φ were estimated from the experimental data. Redlich-Mayer type empirical equation was applied to calculate the limiting apparent molar properties at infinite dilution (Vω∞ and k∞) and corresponding empirical parameters (Sv, Bv, Sk and Bk). The type of interaction either IL-solvent or IL-IL or solvent-solvent occurring in solution were determined from the data of empirical parameters. Furthermore, the temperature dependent apparent molar volume at infinite dilution, V∞ was used to calculate the apparent molar expansibility at infinite dilution, E∞. Moreover, these E∞ values of the studied binary solutions were found to be positive. The making and breaking structure ability of both PILs were analyzed at all experimental conditions. © 2021 The Authors

关键词： Dilution

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A Coupled Bioheat Transfer Model for Customized Whole-Eye Modeling in Retinal Laser Surgery

SSRN

引用

SSRN 2022年

作者： Zhao, P.H. Li, K. Zhang, H. Li, Dong Chen, B. Zheng, Y.P. Li, W.P. Wang, G.X. Fan, L.H. Yao, L. State Key Laboratory of Multiphase Flow in Power Engineering Xi 'an Jiaotong University Shaanxi Xi'An710049 China Department of Ophthalmology The Second Affiliated Hospital of Xi 'an Jiaotong University Shaanxi Xi'An710004 China The First Affiliated Hospital of Xi'an Joao Tong University Shaanxi Xi'An710061 China Department of Mechanical Engineering The University of Akron Akron United States

The photo-thermal effects of laser on tissue is widely used in ophthalmology to treat retinal diseases. By adjusting the pulse duration from nano to tens of seconds, the multi-scale retinal lesion from micro to millimeter size can be thermally targeted. Large scale difference among the target lesions brought extra challenge for retinal laser surgery modeling. In this study, we developed a coupled whole eye model for retinal laser surgery. In the model, Penens bioheat transfer equation was adapted for the whole eye temperature modeling. Simultaneously, we treat the fundus as a multi-layered porous medium made of a tissue matrix buried with highly-absorbing chromophores (melanin or blood). Two-temperature equations, one for the chromophore and the other for the surrounding tissue, will be developed based on the local thermal non-equilibrium theory of porous media. The Pennes model and the two-temperature model was coupled together to calculated the thermal responses of eye during several laser retinal surgery process with pulse duration from nano to tens of seconds. The simulation results proved our model is capable of modeling laser retinal surgery process in different time scale. Furthermore, the present coupled model was applied in a real fundus anatomy from a patient with diabetic retinopathy to illustrate its feasibility in customized laser protocol planning. © 2022, The Authors. All rights reserved.

关键词： Ophthalmology

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Beam dynamics induced by the quantum metric of exceptional rings

arXiv

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arXiv 2024年

作者： Zhang, Zhaoyang Septembre, Ismaël Liu, Zhenzhi Kokhanchik, Pavel Liang, Shun Liu, Fu Li, Changbiao Wang, Hongxing Liu, Maochang Zhang, Yanpeng Xiao, Min Malpuech, Guillaume Solnyshkov, Dmitry Key Laboratory for Physical Electronics and Devices The Ministry of Education Shaanxi Key Lab of Information Photonic Technique School of Electronic Science and Engineering Faculty of Electronics and Information Xi’an Jiaotong University Xi’an710049 China Institut Pascal PHOTON-N2 Université Clermont Auvergne CNRS Clermont INP Clermont-FerrandF-63000 France Naturwissenschaftlich-Technische Fakultät Universität Siegen Walter-Flex-Straße 3 Siegen57068 Germany International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Physics University of Arkansas FayettevilleAR72701 United States Paris75231 France

Topological physics has broadened its scope from the study of topological insulating phases to include nodal phases containing band structure singularities. The geometry of the corresponding quantum states is described by the quantum metric which provides a theoretical framework for explaining phenomena that conventional approaches fail to address. The field has become even broader by encompassing non-Hermitian singularities: in addition to Dirac, Weyl nodes, or nodal lines, it is now common to encounter exceptional points, exceptional or Weyl rings, and even Weyl spheres. They give access to fascinating effects that cannot be reached within the Hermitian picture. However, the quantum geometry of non-Hermitian singularities is not a straightforward extension of the Hermitian one, remaining far less understood. Here, we study experimentally and theoretically the dynamics of wave packets at exceptional rings stemming from Dirac points in a photonic honeycomb lattice. First, we demonstrate a transition between conical diffraction and non-Hermitian broadening in real space. Next, we predict and demonstrate a new non-Hermitian effect in the reciprocal space, induced by the non-orthogonality of the eigenstates. We call it transverse non-Hermitian drift, and its description requires biorthogonal quantum metric. The non-Hermitian drift can be used for applications in beam steering. Copyright © 2024, The Authors. All rights reserved.

关键词： Topology

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Strong Metal-Support Interaction-Induced Hydrogen Spillover Boosts Thermocatalytic Ammonia Decomposition

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Small 2025年 e2500830页

作者： Chen, Zechang Jiang, Biao Lu, Zijie Huang, Jie Shi, Jinwen Liu, Maochang International Research Center for Renewable Energy & State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China Suzhou Academy of Xi'an Jiaotong University Jiangsu Suzhou215123 China

Efficient non-noble-metal catalysts are essential for the industrial application of ammonia decomposition reaction (ADR). This work reports a Ni-Co bimetallic thermocatalyst supported by BaCe0.8Y0.2O3-δ (BCY), a proton-conducting cermet, demonstrating state-of-the-art ADR performance. This catalyst achieves 100% NH3 conversion at 550 °C with a gas hourly space velocity of 9000 mL h−1 gcat−1 and 95.1% conversion at 520 °C, notably lowering ADR temperature requirements. It also demonstrates outstanding stability under diverse conditions. The superior ADR activity arises from Ni-Co synergies, Ce's strong basicity, as well as extensive hydrogen spillover facilitated by Y doping-induced high oxygen vacancies. Specifically, BCY's strong adsorption of H* promotes the migration of H* from the active Ni/Co surface to oxygen sites of the support and subsequent rapid diffusion as OH* in oxygen vacancy channels. This metal-support-interaction-induced hydrogen spillover effect further liberates the original active sites and boosts ammonia activation. © 2025 Wiley-VCH GmbH.

关键词： Cermets

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Characterizing the catalyst fluidization with field synergy to improve the amine absorption for CO2 capture

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Chinese Journal of Chemical engineering 2019年第7期27卷 1608-1617页

作者： Yunsong Yu Chen Zhang Zaoxiao Zhang Geoff Wang School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China School of Chemical Engineering The University of QueenslandSt LuciaQLD 4072Australia

There are great interests to capture the CO2 to control the greenhouse gas *** absorption of CO2 is being taken as an effective way to capture CO2 in ***,the amine absorption of CO2 is cost-ineffective due to great energy consumption and solution *** order to reduce the capture cost,catalyst fluidization is proposed here to intensify the mass transfer and heat *** fluidization with field synergy and DFT model is developed by incorporating the effects of catalyst reaction kinetics,drag force and multi-field into the mass transfer,heat transfer,fluid flow and catalyst *** with an improved distributor are performed well to validate the *** reaction kinetics is determined by the DFT simulation and *** mass transfer coefficient in the fluidized reactor is identified as 17%higher than the conventional packed *** the field synergy of catalyst fluidization,the energy consumption for CO2 desorption is reduced by 9%.Stepwise operation and inclination reactor are used to improve catalyst fluidization process.

关键词： CO2 capture Catalyst fluidization Mass transfer DFT Energy consumption Field synergy

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Corrigendum to “Numerical simulation of an externally heated fixed bed reactor for coal pyrolysis based on porous media” [Chem. Eng. Res. Des. 211 (2024) 137–151]

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Chemical engineering Research and Design 2025年 218卷 454-454页

作者： Haoyue Li Yuanpei Luo Fei Dai Jun Sui Hongguang Jin Laboratory of Distributed Energy Systems and Renewable Energy Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China

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Non-Hermitian delocalization in a 2D photonic quasicrystal

arXiv

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arXiv 2023年

作者： Zhang, Zhaoyang Liang, Shun Septembre, Ismaël Yu, Jiawei Huang, Yongping Liu, Maochang Zhang, Yanpeng Xiao, Min Malpuech, Guillaume Solnyshkov, Dmitry Key Laboratory for Physical Electronics and Devices The Ministry of Education Shaanxi Key Lab of Information Photonic Technique School of Electronic Science and Engineering Faculty of Electronics and Information Xi’an Jiaotong University Xi’an710049 China Institut Pascal PHOTON-N2 Université Clermont Auvergne CNRS Clermont INP Clermont-FerrandF-63000 France International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Physics University of Arkansas FayettevilleAR72701 United States National Laboratory of Solid State Microstructures School of Physics Nanjing University Nanjing210093 China Paris75231 France

Quasicrystals show long-range order, but lack translational symmetry. So far, theoretical and experimental studies suggest that both Hermitian and non-Hermitian quasicrystals show localized eigenstates. This localization is due to the fractal structure of the spectrum in the Hermitian case and to the transition to diffusive bands via exceptional points in the non-Hermitian case. Here, we present an experimental study of a dodecagonal (12-fold) photonic quasicrystal based on electromagnetically-induced transparency in a Rb vapor cell. The transition to a quasicrystal is obtained by superposing two honeycomb lattices at 30◦ with a continuous tuning of their amplitudes. Non-Hermiticity is controlled independently. We study the spatial expansion of a probe wavepacket. In the Hermitian case, the wavepacket expansion is suppressed when the amplitude of the second lattice is increased (quasicrystal localization). We find a new regime, where increasing the non-Hermitian potential in the quasicrystal enhances spatial expansion, with the C12 symmetry becoming visible in the wavepacket structure. This real-space expansion is due to a k-space localization on specific quasicrystal modes. Our results show that the non-Hermitian quasicrystal behavior is richer than previously thought. The localization properties of the quasicrystals can be used for beam tailoring in photonics, but are also important in other fields. Copyright © 2023, The Authors. All rights reserved.

关键词： Quasicrystals

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