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Design on the Experimental Table for CO2 Refrigeration System with Turbo Expander

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Design on the Experimental Table for CO2 Refrigeration Syste...

The 5thInternational Conference on Cryogenics and Refrigeration ICCR 2013(第五届国际低温制冷会议)

作者： Ma J.L. Liu C.H. Sun W. Wang M. Lai T.W. Hou Y. State Key Laboratory of Multiphase Flow in Power Engineering Xi''an Jiaotong UniversityXi''an 710049China School of Energy and Power Engineering Xi''an Jiaotong UniversityXi''an 710049China School of Energy and Power EngineeringXi''an Jiaotong UniversityXi''an 710049China

Exploring Comprehensive Properties of a Novel Shape-Stabilized Composite Phase Change Material Of Lauric Acid-Palmitic Acid- Tetradecyl Alcohol/Vitrified Beads for Thermal Energy Storage

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SSRN 2024年

作者： Yan, Qiuhui Jia, Mengyu Luo, Jieren Meng, Zeyu School of Building Services Science and Engineering Xi’an University of Architecture and Technology Xi’an710055 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

Excellent thermal properties are the cornerstone of phase change materials (PCMs) employed for energy storage, and leakage prevention and sufficient strength are the key problems that must be solved in the practical application process of PCMs. Therefore, the advantages of ternary PCMs (Lauric Acid-Palmitic Acid-Tetradecyl Alcohol, LA-PA-TA) and adsorbent carriers (Vitrified Bead, VB) are integrated to obtain a novel LA-PA-TA/VB composite PCM which exhibits favorable phase change temperature (20.1°C-20.5°C) and excellent subcooling (0.4°C). Then, the novel LA-PA-TA/VB is encapsulated with five materials to form shape-stabilized PCMs to reduce leakage. The experiments show that a shape-stabilized LA-PA-TA/VB (SS-LA-PA-TA/VB) encapsulated with the real stone paint emulsion-cement powder presents the optimal packaging effect, namely superior stability and reliability with low mass loss ratio of only 2.67% after 50 times phase change cycles. Next, the SS-LA-PA-TA/VB of the optimal package is further made into thermal energy storage mortar (TESM) with different SS-LA-PA-TA/VB content. It is shown that the thermal properties of TESM increase and the mechanical properties decrease with LA-PA-TA/VB. However, even with the LA-PA-TA up to 30% (30TESM), the compressive strength, flexural strength, apparent density, water absorption, and softening coefficient of the TESM still meets the Chinese National Standard, and some microscopic mechanisms have been investigated. Lastly, temperature regular ability and heat insulation performance of 30TESM and reference mortar are compared by temperature probe embedded inside the mortar blocks and installed in experiential small room. The results present that internal temperature of the mortar blocks, backside and central temperature of small room are 5.4°C, 5.6°C and 2.1°C lower than that of the reference group, respectively. It is thus clear that the novel low cost TESM exhibits a good temperature damping effect and temperature control p

关键词： Phase change materials

Rotor Dynamic Analysis of Supercritical Carbon Dioxide Bryton Cycle Coaxial Integrated Unit

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Rotor Dynamic Analysis of Supercritical Carbon Dioxide Bryto...

Prognostics and System Health Management Conference (PHM-Qingdao)

作者： Xiaokang Xu Yi Yang Jiangfeng Wang Juwei Lou Liangqi Chen State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an China Laboratory of Science and Technology on Integrated Logistics Support College of Intelligence Science and Technology National University of Defense Technology Changsha China

The rotor system plays a very important role in supercritical carbon dioxide Brayton cycle system, and its dynamic problem will directly affect the motion stability and safety of the whole unit. In this paper, the rotor dynamic model of supercritical CO 2 coaxial unit is established by finite element method, and the critical speed, modal shape and unbalance response of the rotor are studied. The first seven critical speed of the rotor and the first seven natural frequency of the rotor at the working speed are calculated. The bending modal of the rotor and the position where the rotor amplitude is the largest are analyzed, which can provide reference for the optimization design of the rotor stability. The influences of mass unbalances at the operational speed of rotor are analyzed. The research can provide some suggestions for the optimal design and actual operation of the supercritical CO 2 coaxial integrated unit.

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Enhanced Low-Temperature Behavior of Selective Catalytic Reduction of Nox by Co on Fe-Based Catalyst with Looping Oxygen Vacancy

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SSRN 2022年

作者： Pan, Yuqing Li, Na Li, Ke Ran, Shiyuan Wu, Chenyang Zhou, Qulan Liu, Jiyuan Li, Shuzhou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Materials Science and Engineering Nanyang Technological University Singapore639798 Singapore Singapore138634 Singapore

The industrial applications of de-NOx require the high activity window of the catalysts to be shifted from high to low temperatures for energy saving. Selective catalytic reduction (SCR) of NOx by CO, as an alternative to NH3-SCR, is a promising de-NOx technology that facilitates the synergistic removal of pollutants. Herein, we report a new Fe2O3/amorphous SiO2 catalyst with high low-temperature activity for CO-SCR. A combination of experiments and density functional theory (DFT) calculations obtains direct evidence that an optimal content of oxygen vacancy enhances the low-temperature NO conversion ratio and N2 selectivity of Fe2O3-based catalyst to over 80% and maintain 100% CO conversion by promoting NN coupling via ONNO/N2O and NCO/NNCO2 intermediates. Compared with conventional defect engineering, such as doping other metals or artificially generating oxygen defects, the α-Fe2O3 (110) facet automatically enables an oxygen vacancy generation-filling cycle in the CO-SCR reaction, following Mars-van Krevelen (MvK) mechanism. This work advances a fundamental understanding of CO-SCR reaction mechanism over Fe2O3-based catalysts and provides insights for future studies to improve heterogeneous metal oxide catalysts. © 2022, The Authors. All rights reserved.

关键词： Oxygen vacancies

Experimental Study on the Treatment of low C/N ratio disposal of sewage with BAF

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AIP Conference Proceedings 2010年第1期1207卷 157-161页

作者： W. J. Wang T. Ma W. Cheng aKey Laboratory of Northwest Water Resources and Environmental Ecology of Education Ministry Xi’an University of Technology Xi’an 710048 China bState Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiao tong University China

The Biological Aerated Filter (BAF) is a simple, high‐efficient, low‐consumptive for new biological membrane method correspond to the situation of china, will be one of the main technical measures to solve the progressive deterioration of water environment problem faced china especially medium and small towns. This paper focuses on the experimental study and mechanism analysis in which the up flow, cocurrent gas‐water, single‐stage BAF was adopted on treatment domestic wastewater, the results showed that BAF has good performance in treating domestic sewage, and it had steady treatment effect with different pollution loads.

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Mild Combustion of a Premixed Nh3/Air Jet Flame in Hot Coflow Versus its Ch4/Air Counterpart

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SSRN 2023年

作者： Li, Pengfei Wang, Guochang Liu, Xiangtao Shi, Guodong Cai, Xiao Liu, Zhaohui Mi, Jianchun State Key Laboratory of Coal Combustion School of Energy and Power Engineering Huazhong University of Science and Technology Wuhan430074 China College of Engineering Peking University Beijing100871 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Dalian Maritime University China

MILD combustion is very suitable for solving the problems of unstable flame and high NOx emission (ENOx ) for ammonia fuel, but the related studies are rare. This work numerically investigates the MILD combustion characteristics of a premixed NH3/air jet flame in hot coflow (JHC) under different jet equivalence ratio (ΦJ), coflow temperature (TC) and oxygen level (XO2,C). For comparison, the similar CH4/air MILD-JHC flames are also calculated. Results show that the NH3 flame generally has lower temperature rise and heat release as well as larger reaction zone than CH4. This may suggest that the former flame can develop to the MILD regime more easily. ENOx is two orders higher from the NH3 than CH4 flame at all TC and XO2,C for ΦJ 1, ENOx of the NH3 flame quickly drops to near zero, but ENH3 and EH2 are very high (~1000 ppm) and the combustion efficiency is low. Moreover, ENOx increases quickly (slowly) with XO2,C (TC) while ENH3 and EH2 are quite low at TC ≥ 1300 K and XO2,C ≥ 1% for the NH3 flame. ENOx mainly comes from NO but N2O is also important at low ΦJ and TC. Therefore, considering all ENOx , ENH3, EH2 and the burning efficiency, the optimal conditions for NH3 MILD combustion are ΦJ =1, TC ≥ 1500 K and XO2,C =1%-3%. In addition, compared to the conventional flame, the NH3 MILD combustion can reduce ENOx by 1-2 orders. © 2023, The Authors. All rights reserved.

关键词： Ammonia

Effect of Fuel System on the Heat Releasing Method and flow-Path Design of Rocket-Based Combined Cycle Engine

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Effect of Fuel System on the Heat Releasing Method and Flow-...

International Conference on Mechanical and Aerospace engineering (ICMAE)

作者： Xiao Liu Yinhu Wang Yiyan Yang Lei Shi Dekun Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China Beijing Institute of Long March Vehicle Beijing China Science and Technology on Combustion Internal Flow and Thermal-structure Laboratory Northwestern Polytechnical University Xi’an China

Multi-components rocket-based combined cycle (RBCC) engine is widely applied in most two-stage-to-orbit program due to stable operation performance under variable flight conditions. Present researches numerically compared RBCC’s performance under ramjet mode and scramjet mode, respectively, by using two fuel system, hydrogen and kerosene together with a $\mathrm{k}-\omega$ SST turbulence model. Researches showed that the combustor area ratio should be increased to keep stable pressure difference balance between inflow and flame because of higher caloric value using hydrogen. Distributed heat addition method is benifit for overall performance improvement when using hydrogen. Different from using kerosene, head should be delayedly added in combustor downtream under scramjet mode. Moreover, the advanced heat addition amount should be decreased under ramjet mode to ensure effective isolator operation.

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Enhancing Vertical-Axis Tidal Turbines with Strategic Superhydrophobic Surfaces for Optimized Aerodynamic and Self-Starting Performances

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SSRN 2024年

作者： Yin, Dawei Sun, Jinjing School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Shanghai Key Laboratory of Power Energy in Multiphase Flow and Heat Transfer Shanghai200093 China

As observation and research on nature deepen, bionic and hydrophobic surface drag reduction are gaining increasing popularity among researchers. The application of bionic principles and hydrophobic surface technologies in the field of fluid dynamics has opened up new avenues for enhancing the performance of various engineering systems, including vertical-axis tidal turbines (VATTs). By mimicking the natural mechanisms observed in certain species, such as the lotus effect, researchers have been able to develop superhydrophobic surfaces (SHS) that significantly reduce drag in fluid ***, SHS have been applied uniformly across the entire surface of an airfoil. However, this study takes a more nuanced approach by investigating the impact of SHS application at different positions on the airfoil. Through numerical simulations, the study explores how varying the distribution of SHS can influence the power coefficient (Cp), a key performance metric for VATTs . The findings from the study are quite revealing. At a tip speed ratio (TSR) of 1.68, the study observes that applying SHS to 30% of the chord length near the leading edge of the airfoil yields the maximum relative power coefficient benefit, with an increase of up to 34.8%. This suggests that strategic placement of SHS can lead to significant performance improvements without the need for uniform application, which could potentially reduce material costs and maintenance requirements. Moreover, the study also finds that applying SHS only on the inner surface of the VATT can result in a 32% increase in the power coefficient. This indicates that the inner side of the airfoil, which experiences the higher pressure side of the fluid flow, is particularly sensitive to the drag reduction effects of SHS. The leading edge of the airfoil is another critical area where SHS application can have a substantial impact. The leading edge is the first point of contact between the airfoil and the fluid, and any reduc

关键词： Drag reduction

An optimal design of the widths of heat affect zone, fusion zone, and near interface zone in a dissimilar metal welded joint

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Material Design and Processing Communications

Material Design and Processing Communications 2020年第5期2卷

作者： Guo, Guoliang Yang, Jie Wang, Lei Liu, Guiqiu Zhang, Baozhong Zhang, Sihan 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 Shanghai China Consumer Appliances Centre Shandong Product Quality Inspection Research Institute Shandong China

The optimal design of the dissimilar metal welded joint is a valuable research issue, whether optimize the material, processing technology, dimension, or anything else. The fracture behavior of the dissimilar metal welded joint have been found affected by the widths of heat affect zone, fusion zone, and near interface zone. In this study, the optimal design of the widths of heat affect zone, fusion zone, and near interface zone in the dissimilar metal welded joint was further studied systematically. Firstly, a dissimilar metal welded joint, which used in the nuclear power plants with either heat affect zone crack or fusion zone crack, was selected, and a width mismatch coefficient MW was defined. In addition, the crack propagation paths and J-resistance curves of the dissimilar metal welded joints under different MW induced by the widths of heat affect zone, fusion zone, and near interface zone were calculated. Based on the obtained results, the widths of heat affect zone, fusion zone, and near interface zone were optimized. This study will provide support for the design of the dissimilar metal welded joint and is significant to the structure integrity assessment of the nuclear power plants. © 2019 John Wiley & Sons, Ltd.

关键词： Nuclear fuels