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International Conference on Advances in Materials and Manufacturing Processes

作者： Wang, Weishu Zhang, Hongsheng Bi, Qincheng Liu, Jun North China Inst Water Conservancy & Hydroelect P Sch Elect Power Zhengzhou 450011 Peoples R China Xi An Jiao Tong Univ State Key Lab MultiPhase Flow Power Engn Xian 710049 Peoples R China

ISBN: (纸本)9780878492053

The characteristics of heat transfer enhancement and deterioration in supercritical water reactor core is essential to the reactor efficiency and security. At present, there exists deficiency in the study of core enhanced channels. Two different fins arrangements of the enhanced channels are designed in present paper, which are long-strip fins and equal-distance short fins. At the conditions of the supercritical pressure of 25MPa, the inlet temperature of 350 degrees C and different inlet velocities, the heat transfer enhancement and deterioration characteristics of water flowing in the two different fins arrangements of the enhanced channels were studied and comparatively analyzed. The results show that the heat transfer is enhanced in the channels with fins. The heat transfer enhancement is better in the channel with equal-distance short fins when lower input velocity, better in the channel with long-strip fins when high input velocity. The surface heat transfer coefficients increase with the velocity increases;the surface heat transfer coefficients in equal-distance short fins is two to three times than that in the channel without fins. There exists heat transfer deterioration when the input velocity is lower in the channel without fins and with long-strip fins, no deterioration occurs in the channel with equal-distance short fins. The channel with equal-distance short fins is a relatively reasonable of the three channels.

关键词： Reactor Supercritical fluid Enhanced sub-channel Surface heat transfer coefficient Numerical calculation

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One-pot synthesis of reduced graphene oxide-based PANI/MnO2 ternary nanostructure for high-efficiency supercapacitor applications

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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS 2022年第33期33卷 25355-25370页

作者： Abbas, Sajid Manzoor, Sumaira Abdullah, Muhammad Mahmoud, K. H. Abid, Abdul Ghafoor Khan, Muhammad Shuaib Yasmeen, Ghazala Alsubaie, A. Sa Manzoor, Suryyia Ashiq, Muhammad Naeem Bahauddin Zakariya Univ Inst Chem Sci Multan 60800 Pakistan Govt Coll Univ Dept Chem Lahore Pakistan Taif Univ Coll Khurma Univ Coll Dept Phys Taif Saudi Arabia Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xjtu Saudi Arabia

Energy shortage imposes major global issues, and developing new energy storage devices has become extremely urgent. Because supercapacitors (SCs) have been regarded as inspirational energy storage technologies. Herein, a novel rGO/PANI/MnO2 material was developed via a chemical reduction method for high-rate supercapacitors. The morphological structural & textural properties of fabricated nanostructure been investigated with X-ray diffraction, scanning electron microscope (SEM) & Brunauer-Emmett-Teller (BET). Electrochemical characterization of advanced nanocomposite contains specific capacitance (C-sp) of 1613.7 F g(-1) with enhanced rate capabilities and cycling stability retention of 99.7% with original capacity after 2000 cycles in 2 M KOH. Excellent efficiency of fabricated material is attributed due to small crystallite size, good morphology, and enhanced electrochemical surface area. This study emphasizes the good electrochemical performance of rGO/PANI/MnO2 on carbon fiber. The flake like morphology of the composite provides numerous electronic conduction routes, and more active sites refer it to be potential candidate for energy storage devices.

关键词： Supercapacitor

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Two-phase flow instability in parallel nine-channel system under rolling condition

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Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 2009年第10期43卷 886-892页

作者： Zhang, You-Jia Su, Guang-Hui Qiu, Sui-Zheng Guo, Yu-Jun State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and Technology Xi'an Jiaotong University Xi'an 710049 China

Two-phase flow instability in parallel multi-channel system was studied under rolling motion condition. A parallel nine-channel model was established by using the control volume integrating method based on the homogeneous flow model with considering the rolling motion condition. The gear method was used to solve the control equations. The influences of the entrance, upward sections and the heating power on the flow instability under rolling motion condition were analyzed. The marginal stability boundary (MSB) under rolling motion condition was obtained. The unstable regions occur in both low and high equilibrium quality regions. The region with low inlet sub-cooling is also unstable. In high equilibrium quality region, the multiplied period phenomenon is found and the chaotic phenomenon appears at the MSB.

关键词： Stability

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Investigation of Macro-fin Structure on Heat Transfer Performance of Close-Loop R410A Flashing Spray Cooling 15

Investigation of Macro-fin Structure on Heat Transfer Perfor...

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15th Triennial International Conference on Liquid Atomization and Spray Systems, ICLASS 2021

作者： Zhou, Zhifu Ji, Renjie Chen, Bin Thrassos, Panidis State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Laboratory of Applied Thermodynamics Mechanical Engineering Aeronautics Department University of Patras Rio Patras26504 Greece

The rapid development in performance, integration and miniaturization of electronics and other high power devices cause huge heat flux values. However, transitional cooling methods can hardly meet the requirement of dissipating effectively the high heat flux at the normal working temperature (usually smaller than 75 oC). The refrigerants flash evaporation spray cooling with phase change has been considered as one of the most promising technologies of heat dissipation for electronic devices and other high power devices due to its high heat removal capability at relatively low surface temperature, cooling uniformity, non-corrosivity. This study presents an experimental study on the heat transfer performance of the close-loop R410A flashing spray cooling, mainly focusing on the influence of macro-fin structure of cooling surface. The flat, square fin, pyramid fin surfaces and a newly designed tetrahedral fin surface are systematically examined. The results indicate that the newly designed tetrahedral fin surface has superior cooling performance than other fin surfaces. © 2021 ICLASS 2021 - 15th Triennial International Conference on Liquid Atomization and Spray Systems. All Rights Reserved.

关键词： Electronic cooling

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A comprehensive model for uniform heat flux inside cavity receiver with air-carbon mixture

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Energy Procedia 2017年 142卷 177-183页

作者： Yabin Jin Jiabin Fang Jinjia Wei Xinhe Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China

Cavity receiver is one of the main components of efficient concentrating solar collector systems. It has the ability to operate at relatively higher temperature and efficiency. The safety and thermal efficiency of solar cavity receiver can affect the efficiency of the whole power system. However, the non-uniform distribution of heat flux and temperature inside the cavity tends to cause the operation instability and bring damage to the tube as well. In the present work, a comprehensive numerical model was developed by coupling Monte Carlo Ray Tracing (MCRT) and Finite Volume Method (FVM) to simulate the thermal performance of a 2D square solar cavity filled with air-carbon particle mixture. Firstly, the complicated photon transmission in the air-carbon particle mixture absorber is simplified as the transmission process in the statistically homogenous and isotropic turbid media. The solar heat flux distribution from the aperture to the wall is simulated by MCRT, and the photo-thermal convection process in the cavity receiver is modeled by FVM. Then the two parts are coupled in the cavity receiver by transferring the absorbed energy computed by MCRT to FVM, and this energy is applied as a source term of the energy equation in the FVM part. Based on this model, the temperature and heat flux characteristics of the cavity receiver were studied at various carbon densities. The result indicated that the air-carbon particle mixture can actively take part in the radiation and it appears that it has a remarkable effect on the temperature homogenization. It decreases the temperature of wall 3 dramatically and increases the temperature of wall 2 and wall 4. The relationships between the temperature unevenness and the number particle density were also analyzed. The temperature unevenness on the wall 3 drops most with the increase of number density of carbon particle, from 25.0K to 2.4K. The unevenness of temperature on the top and bottom walls also decreases slightly by 3K. In ad

关键词： solar cavity receiver non-uniform air-carbon particle mixture homogenization Monte Carlo ray tracing Finite volume method

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Identification of the running status of membrane walls in an opposed fired model boiler under varying heating loads

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APPLIED THERMAL engineering 2020年 173卷 115217-115217页

作者： Fu, Jiapeng Liu, Zhuhan Wei, Lin Lin, Leteng Li, Na Zhou, Qulan Ma, Chunyuan Shandong Univ Engn Res Ctr Environm Thermal Technol Sch Energy & Power EngnShandong Key Lab Energy C Natl Engn Lab Reducing Emiss Coal CombustMinist Jinan 250061 Shandong Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Linnaeus Univ Dept Built Environm & Energy Technol S-35195 Vaxjo Sweden

To understand the running status of membrane walls in an opposite firing boiler, a scale-down model furnace was established, and the temperature, heat flux, strain and stress distributions are investigated under four heating loads. Results show that the average membrane wall temperature and heat flux present a continuous increase from 42 degrees C and 16 W/m(2) to 96 degrees C and 50 W/m(2), respectively, with the heating load increase from 25% to full load. The average strain and stress also rise from 88.7 mu m and 0.094 MPa to 152.5 mu m and 0.148 MPa when the heating load increases from 25% to 50%, but then they keep stable when further increasing the heating load. General distribution patterns of each tested parameter are found relatively similar under varying heating loads. High strain and stress distributions are always detected at the middle left zone of side walls and the middle of the rear wall, where wall temperatures are measured high. External fixed constraints and high-temperature thermal strain is found jointly affecting the strain and stress distribution of the membrane wall. A simplified mechanism of how the strain and stress on boiler membrane walls evolve is proposed after comprehensive discussion of the measurement results.

关键词： Opposed fired boiler Membrane walls Heat flux Strain and stress Fixed constraint

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Development of a thermal-mechanical-material behavior analysis code for the dispersion-plate-type fuel 16

Development of a thermal-mechanical-material behavior analys...

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16th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2015

作者： Wu, Yingwei Lu, Qing Deng, Yangbin Zhang, Dalin Tian, Wenxi Qiu, Suizheng Su, Guanghui State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi'an Jiaotong University Xi'an710049 China Department of Nuclear Engineering Xi'an Jiaotong University Xi'an710049 China

ISBN: (纸本)9781510811843

In this study, the relevant thermal-hydraulic, mechanic-material and burnup effect calculation models were established. On the basis of these mathematic and physic models, a thermal- mechanic-material coupling analysis code for a dispersion-plate-type fuel assembly was independently developed with the consideration of the burnup effects. The coupling program was applied to perform the thermal-mechanical-material behavior analysis of a dispersion-plate-type fuel assembly. Major physical parameters at different burnup stages were well predicted, including flux distribution, temperature profile, Mises stress and mechanic deformations. The result shows that geometric sizes of flow channels are the key parameters determining the coolant flux distribution and the temperature profile of the edge plate presents substantial asymmetry as a result of asymmetric heat transfer caused by the asymmetric geometry. Furthermore, the equivalent stress of base material increased rapidly with burnup because of the thermal expansion and burnup effects, which resulted in substantial plastic deformation and mechanical damage. In addition, the mechanism and process of blistering was investigated for blistering prediction. The result shows that due to the increasing fission gas pressure and the deteriorating yield stress of the cladding, fuel plate blistering may happen when the burnup depth up to a certain value and fuel plate will finally fall into failure as a result of over plastic deformation.

关键词： Plastic deformation

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Secondary side flow field of steam generator with coupled heat transfer from primary to secondary side fluid

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Yuanzineng Kexue Jishu/Atomic Energy Science and Technology 2014年第8期48卷 1398-1405页

作者： Cong, Teng-Long Tian, Wen-Xi Qiu, Sui-Zheng Su, Guang-Hui Department of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The 3D flow characteristics in SG can provide input for the analysis of flow induced vibration (FIV). The secondary side flow field was simulated based on the porous media model with FLUENT solver. The flow resistances of flow along and cross tubes as well as flow resistances of downcomer, support plates and separators were added to the momentum equation. The 3D heat transfer from primary to secondary side fluid was calculated during iteration and set as the energy source of secondary side fluid, and the calculation results agree well with the design values. Meanwhile, the results show that the resultant localized thermal-hydraulic characteristics were unevenly distributed. The maximum and minimum flow vapor qualities flowing into the primary separators are 0.75 and 0.07, respectively. The average heat transfer coefficients of primary and secondary sides are 15 856.5 and 63 623.0 W/(m2·K), respectively. The maximum heat transfer coefficient of secondary side is 122 862.9 W/(m2·K). The average heat flux of U-tube is 149.9 kW/m2. The maximum cross flow velocity and cross flow energy (ρu2) through the U-bend region are 4.06 m/s and 1 145 J/m3, respectively.

关键词： Porous materials

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Theoretical Kinetics of Radical-Radical Reaction NH2NH + NH2 and Its Implications for Monomethylhydrazine Pyrolysis Mechanism

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JOURNAL OF PHYSICAL CHEMISTRY A 2024年第39期128卷 8501-8511页

作者： Wang, Chunyu Zhao, Qian Zhao, Hao Pu, Binxu Huang, Zuohua Li, Longfei Zhang, Yingjia Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Southwest Jiaotong Univ Dept Fire Protect Engn Chengdu 611756 Peoples R China Xian Aerosp Prop Inst Sci & Technol Liquid Rocket Engine Lab Xian 710100 Peoples R China

Significant discrepancies were observed between the experiments and the simulations for NH2 time-histories in monomethylhydrazine pyrolysis with the robust mechanism proposed by Pascal and Catoire. The rate of formation analyses for NH2 indicated the significance of the reaction NH2NH + NH2 = H2NN + NH3, which has not been well-defined. In this study, ab initio calculations were performed for the theoretical description of the NH2NH + NH2 chemistry. Most stationary points on the potential energy surface were quantified at the CCSD(T)/CBS//M06-2X/aug-cc-pVTZ level, and the multireference methods were employed for barrier-less reaction and some transition states. The temperature- and pressure-dependent rate coefficients were determined using classical and microcanonical variational transition state theories. Four primary reaction channels were identified as competitive: 1) The H atom abstraction reaction yielding N2H2(T) + NH3, dominating at 1350-3000 K across the 0.001-100 atm pressure range. 2) The H atom abstraction reaction forming N2H2(S) + NH3, dominating at 800-1350 K and competing with the processes of chemical activation and collisional stabilization below 800 K. 3) The chemical-activated reaction resulting in H2NN(S) + NH3, dominating below 800 K at 0.001 atm. 4) The collisional-stabilized recombination reaction leading to N3H5, becoming significant as pressure increases and dominating below 600 and 650 K at 1 and 100 atm, respectively. The implications of newly calculated NH2NH + NH2 kinetics for the monomethylhydrazine pyrolysis mechanism were evaluated, and updates were implemented. Sensitivity analyses indicated the necessity of additional research efforts to comprehend the dynamics of CH3NH2 unimolecular and N2H2 + NH2 reaction systems. The rate coefficients presented in this study can be employed to develop the chemical kinetic model of nitryl-containing systems.

关键词： Free radical reactions

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Investigation on Influences of Bubble Location and Momentum Transfer Direction on Liquid Turbulence Modification for the Dilute Bubbly flow

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INTERNATIONAL JOURNAL OF FLUID MECHANICS RESEARCH 2016年第2期43卷 161-181页

作者： Pang, Mingjun Wei, Jinjia Yu, Bo Changzhou Univ Sch Mech Engn Changzhou 213016 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China China Univ Petr Beijing Key Lab Urban Oil & Gas Distribut Technol Beijing 102249 Peoples R China

It is very significant for the effective design and operation of bubbly equipments to understand deeply the liquid turbulence modulation mechanism by bubbles. In the present paper, detailed investigations on modulation of bubbles on the liquid turbulence, for the dilute bubbly flow with a low liquid-phase Reynolds number, were carried out with the developed Euler-Lagrange numerical method when bubbles always stayed in different turbulence layers for the horizontal and vertical channels, respectively. The velocity field of the liquid phase was solved with direct numerical simulation (DNS), and the bubble motion was followed with Newtonian motion equations. The present studies show that the liquid-phase turbulence modulation is tightly related to the bubble location and the momentum transfer direction between bubbles and liquid (i.e., the gravity direction);it should be noted that when bubbles are located in the turbulence buffer layer, the opposite phenomena happen to the liquid turbulence modulation by bubbles for the horizontal and vertical channels.

关键词： Numerical methods

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