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heat transfer enhancement of plate heat exchangers with symmetrically distributed capsules to generate counter-rotating vortices

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INTERNATIONAL JOURNAL OF heat AND MASS transfer 2020年第0期151卷 119455-000页

作者： Jiang, Chen Bai, Bofeng Wang, Haibo Shi, Jiqing Tang, Xiaoying Zhou, Wenxue Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Shanghai Lanbin Petrochem Equipment CO LTD Shanghai 201518 Peoples R China Machinery Ind Shanghai Lanya Petrochem Equipment Shanghai 201518 Peoples R China Shanghai Inst Equipments Inspect & Tech Res Shanghai 200062 Peoples R China Lanzhou Res Ctr Heat Transfer & Energy Conservat Lanzhou 730050 Peoples R China

Capsule-type plate heat exchanger takes advantages of low flow resistance and high overall performance. To obtain greater energy efficiency, a new type named symmetrical capsule plate heat exchanger (SCPHE) is constructed based on the idea of counter-rotating vortices. For SCPHEs, the adjacent capsules distribute symmetrically at the same-side of the plate, and the capsules keep an angle of 45 degrees with the main flow direction. The heat transfer enhancement and the influences of capsule geometries were studied numerically. Counter-rotating vortices generating in the channels promote the swirl flow and disturb the boundary layer. Both fluid impinging and the vortices dominate the heat transfer enhancement, which become much stronger under smaller capsule, resulting in higher heat transfer coefficient. The correlations of Nu and f considering the effects of the capsule geometries are developed. SCPHEs show higher energy efficiency than capsule-type plate heat exchangers and chevron-type plate heat exchangers in the view of PEC and EEL. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Plate heat exchanger Symmetrical capsule Counter-rotating vortices Fluid impingement Energy efficiency

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Fluoride-Salt-Cooled High-Temperature Reactor: An Integrated Nuclear-Based Energy Production and Conversion System

SSRN

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SSRN 2023年

作者： Zhang, Dalin Li, Xinyu Jiang, Dianqiang Zhou, Xingguang Lv, Xindi Yun, Shichang Wu, Wenqiang He, Xuanang Li, Haoyang Min, Xin Chen, Kailong Tian, Wenxi Qiu, Suizheng Su, Guanghui Zhao, Quanbin Fu, Yao Tang, Chuntao Zhuo, Wenbin Li, Jinggang Zuo, Jiaxu State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Shanghai Institute of Applied Physics Chinese Academy of Sciences Shanghai201800 China Shanghai Nuclear Engineering Research & Design Institute Co. Ltd. Shanghai200233 China CNNC Key Laboratory on Nuclear Reactor Thermal Hydraulics Technology Nuclear Power Institute of China Chengdu610213 China China Nuclear Power Technology Research Institute Guangdong Shenzhen518000 China Nuclear and Radiation Safety Center Ministry of Ecology and Environment Beijing100082 China

Based on the analysis of energy structure and the development trends of advanced nuclear energy technology, combining the complementary advantages of nuclear energy and other energy sources in China, the Fluoride-salt-cooled High-temperature Reactor(FuSTAR) system has been proposed. FuSTAR system is designed to address production capacity issues in areas with energy shortages or resource concentration and can be combined with high-temperature process heat to achieve high-value-added processes such as hydrogen production. In this paper, the design and optimization processes of FuSTAR are described from three aspects: the neutronic and thermal-hydraulic system, the thermal transport system, and the power cycle system. Tri-structural isotropic fuel combined with helical cruciform elements has been studied in detail on the neutron physics and thermal-hydraulic properties, and the flow and heat transfer experiment is carried out for the first time. The multilayer nonlinear programming method has been applied to the design of thermal transport systems and the passive residual heat removal system and proved to be fast and efficient. Then the optimal parameters and configuration of the thermoelectric conversion system are obtained directly by using the superstructure optimization method, which saves computing resources greatly. Based on the above design and parameters, the inherent safety of FuSTAR is demonstrated through deterministic safety analysis. In addition, the iodine-sulfur cycle technology is also designed and analyzed, and the characteristics of tritium production in FuSTAR are calculated. The research provides important guidance for the detailed design and operation of FuSTAR. Moreover, this study highlights the significant potential of integrating nuclear energy with other energy sources in an optimized energy-production system. Based on the current research findings, prospects for future research directions are also suggested. © 2023, The Authors. All rights r

关键词： High temperature reactors

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Numerical Investigation of flow Dynamics and Cooling Performance in Combined Porosity Structures at the Leading Edge of a Hypersonic Vehicle

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SSRN 2024年

作者： Chen, Weijie Tu, Shantung Chu, Tiange Su, Huijuan Wang, Ke Wang, Yongqing School of Mechanics and Safety Engineering Zhengzhou University Zhengzhou450001 China School of Mechanical and Power Engineering Zhengzhou University Zhengzhou450001 China Key Laboratory of Process Heat Transfer and Energy Saving of Henan Province Zhengzhou University Zhengzhou450002 China East China University of Science & Technology Shanghai200237 China Faculty of Arts Science & Technology University of Northampton Northampton United Kingdom

Transpiration cooling presents significant promise for enhancing thermal protection technology (TPT) in hypersonic vehicles. However, leading edge structures with single-homogeneous porosity (LE-SHP) frequently encounter excessive flow resistance at the stagnation point, resulting in non-uniform temperature distribution in localized regions, which adversely influences the TPT effectiveness. In response, a gradient-homogeneous combined porosity structure (LE-GHP) based on local thermal equilibrium (LTE) model was introduced in this paper. The cooling mechanism of LE-GHP at Mach 7 was analyzed using a step-by-step numerical simulation method. The effects of coolant injection rate and combined porosity distribution on coolant flow and cooling performance were investigated. Furthermore, the impact of discontinuous transpiration surfaces (GHP-DT) with varying lengths (‌δ) on downstream cooling performance was evaluated. The results indicate that flow resistance at the stagnation point is reduced by LE-GHP, forming a more uniform cooling gas film that significantly mitigates the thermal impact of high-enthalpy freestream on the transpiration surface. Compared to the LE-SHP, superior cooling performance with lower endothermic power under different coolant injection rate conditions are demonstrated by LE-GHP, improving the temperature distribution uniformity of the transpiration surface by 30.56-70.79% and increasing the average cooling efficiency of the hot surface by 11.48-13.01%. Additionally, when the gradient porosity region ranges from 0° to 60° (θ=60°), the endothermic power of transpiration surface is reduced by up to 64.88%, with a corresponding increase in the thermal protection effect on the hot surface by up to 28.17%. In comparison to θ=60°, GHP-DT (θ=60°, ‌δ=1 mm) not only ensures the reliability of thermal protection material, but also improves the temperature distribution uniformity of hot surface by 18.36%. This research provides valuable insights into the

关键词： Hypersonic vehicles

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Predicting radiative heat transfer in axisymmetric cylindrical enclosures using the collocation spectral method

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INTERNATIONAL COMMUNICATIONS IN heat AND MASS transfer 2020年 117卷 104789-104789页

作者： Zhou, Rui-Rui Li, Ben-Wen Sun, Ya-Song Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Dalian Univ Technol Sch Energy & Power Engn Key Lab Ocean Energy Utilizat & Energy Conservat Minist Educ Dalian 116024 Peoples R China Northwestern Polytech Univ Sch Power & Energy Shaanxi Key Lab Thermal Sci Aeroengine Syst Xian 710072 Peoples R China Yangtze River Delta Res Inst NPU Ctr Computat Phys & Energy Sci Taicang 215400 Peoples R China

In this paper, the collocation spectral method (CSM) is extended to solve the radiative transfer equation (RTE) in two-dimensional axisymmetric cylindrical medium, and an iterative solver based on Schur decomposition is developed for the spectral discretized equations. Then the performance of CSM is assessed by comparing with the semi-analytic solutions and the discrete ordinates method (DOM). The results show that the layout of angular grid points has great influence on the accuracy of CSM, and rearranging the angular grid can even reduce the ray effect. But a more reliable method to alleviate the ray effect is to decompose the radiative intensity into two components with separate treatments as the modified DOM proposed by Ramankutty and Crosbie (JQSRT, 57(1997) 107-140). Besides, the CSM can offer more accurate results than the DOM with acceptable computational cost and memory consumption, thus can be an alternative for the solution of RTE in cylindrical coordinates. However, the CSM loses its high order convergence accuracy for the two-dimensional problems due to the unavoidable non-smooth distribution of radiative intensity in both spatial and angular domains. Further treatments should be applied to improve the performance of CSM.

关键词： Radiative transfer equation Spectral methods Discrete ordinates method Ray effect Cylindrical medium

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Chemical looping based ammonia production--A promising pathway for production of the noncarbon fuel

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Science Bulletin 2022年第20期67卷 2124-2138,M0004页

作者： Qinghua Lai Tianyi Cai Shik Chi Edman Tsang Xia Chen Runping Ye Zhenghe Xu Morris D.Argyle Dong Ding Yongmei Chen Jianji Wang Armistead G.Russell Ye Wu Jian Liu Maohong Fan College of Engineering and Applied Science University of WyomingLaramie WY 82071USA School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai 200093China Wolfson Catalysis Department of ChemistryUniversity of OxfordOxford Ox13QRUK College of Chemistry and Chemical Engineering Ocean University of ChinaQingdao 266100China State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Department of Chemical and Materials Engineering University of AlbertaEdmonton Alberta T6G1H9Canada Department of Chemical Engineering Brigham Young UniversityProvo UT 84602USA Idaho National Laboratory Idaho Falls ID83415USA College of Chemistry Beijing University of Chemical TechnologyBejing 100029China School of Chemistry and Environmental Science Henan Normal UniversityXinxiang 453007China School of Civil and Environmental Engineering Georgia Institute of TechnologyAtlanta GA 30332USA MIIT Key Laboratory of Thermal Control of Electronic Equipment School of Power EngineeringNanjing University of Science&TechnologyNanjing 210094China DICP-Surrey Joint Centre for Future Materials Department of Chemical and Process Engineeringand Advanced Technology InstituteUniversity of SurreyGuilford Surrey GU27XH UK

Ammonia, primarily made with Haber-Bosch process developed in 1909 and winning two Nobel prizes, is a promising noncarbon fuel for preventing global warming of 1.5 °C above pre-industrial levels. However,the undesired characteristics of the process, including high carbon footprint, necessitate alternative ammonia synthesis methods, and among them is chemical looping ammonia production(CLAP) that uses nitrogen carrier materials and operates at atmospheric pressure with high product selectivity and energy efficiency. To date, neither a systematic review nor a perspective in nitrogen carriers and CLAP has been reported in the critical area. Thus, this work not only assesses the previous results of CLAP but also provides perspectives towards the future of CLAP. It classifies, characterizes, and holistically analyzes the fundamentally different CLAP pathways and discusses the ways of further improving the CLAP performance with the assistance of plasma technology and artificial intelligence(AI).

关键词： Ammonia synthesis Chemical looping Nitrogen carrier Renewable fuels Energy carrier

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Freezing morphologies of impact water droplets on an inclined subcooled surface

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INTERNATIONAL JOURNAL OF heat AND MASS transfer 2021年 181卷 121843-121843页

作者： Zhu, Fang-Qi Fang, Wen-Zhen New, Tze How Zhao, Yugang Yang, Chun Nanyang Technol Univ Sch Mech & Aerosp Engn 50 Nanyang Ave Singapore 639798 Singapore Natl Univ Singapore Dept Mech Engn Singapore 117575 Singapore Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Freezing of impact water droplets is ubiquitous in nature. Prior studies mostly focus on the freezing shapes of droplets impinging perpendicularly to a cold surface. In this work, we investigate how the frozen morphologies of impact water droplets are formed on a subcooled inclined (45 degrees) surface. To en-hance the coupling between droplet impact dynamics and solidification, we hereby conduct the exper-iments on superhydrophilic surfaces under various substrate temperatures (-45 degrees C < Ts <-25 degrees C) and droplet impact velocities (1.33 m/s < V 0 < 3.96 m/s) where the cooling rate is significantly improved. In-triguingly, we discover four types of frozen droplet morphologies, namely elliptical cap, half ring + cap I , half ring + cap II , and half ring + single ring, depending upon the impact velocity and substrate temper-ature. The formation of such morphologies resulted from the competition between the timescales associ-ated with droplet solidification and impact hydrodynamics are appreciably altered by the inclined impact due to symmetry breaking as compared to the normal impact. To unravel the underlying physics, based on scaling analyses we propose a phase diagram to show how frozen morphologies are controlled by droplet impact and freezing related timescales, and find that such phase diagram can corroborate with the experimental findings. (c) 2021 Elsevier Ltd. All rights reserved.

关键词： impact droplet freezing morphology inclined surface droplet spreading

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On-Line Measurement of Ultralow Mass Concentration Particulate Based on Light Scattering Coupled with Beta Ray Attenuation Method

SSRN

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SSRN 2022年

作者： Liu, Xiaowei Huang, Yubo Wang, Zhaofeng Jiang, Meng Zhou, Zijian Xu, Minghou Han, Jinke Yang, Bin Fan, Xinfeng State Key Laboratory of Coal Combustion School of Energy and Power Engineering Huazhong University of Science and Technology 1037 Luoyu Road Wuhan430074 China JXIC Energy Technology Research Institure Nanchang330000 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Wuhan Tianhong Environmental Protection Industry Co. Ltd Yuhong Environmental Protection Science and Technology Industrial Park No.11 Huashiyuan North Road Miaoshan District Donghu high tech Development Zone Wuhan430074 China

Light scattering method is the most commonly used method for on-line measurement of ultralow particulate matter mass concentration. However, when the particle characteristics change, the effectiveness of the empirical relationship decreases, which would lead to a sizeable deviation. To accurately measure the mass concentration of particulate matter in real-time, a coupling measurement idea of light scattering and beta-ray attenuation is proposed. The beta-ray attenuation is little affected by particle properties and accurately reflects the average PM mass concentration in the measured period. The single calibration method (M1), periodic calibration method (M2), average calibration method (M3), and asymmetric factor calibration method (M4) are formed based on the coupling idea. The results of all methods are perfect when the particle size is unchanged. However, when the particle sizes fluctuate frequently, the results of M1, M2, and M3 deviate seriously from the actual value, and the applicable working conditions have limitations. The results of M4 are in good agreement with the actual value, and the effectiveness is not limited by the particle size. Finally, the prototype based on experimental exploration was developed and had been continuously operated for more than 528 hours at a 1000 MW unit of a coal-fired power plant. © 2022, The Authors. All rights reserved.

关键词： Particle size

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Role of feedstock properties and hydrothermal carbonization conditions on fuel properties of sewage sludge-derived hydrochar using multiple linear regression technique

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FUEL 2020年 271卷 117609-000页

作者： Zheng, Xiaoyuan Jiang, Zhengwei Ying, Zhi Song, Jiaxing Chen, Wei Wang, Bo Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

Hydrothermal carbonization (HTC) has emerged as a promising method for sewage sludge treatment. It is important to understand how process conditions (i.e. temperature, duration, and HTC reaction severity) and feedstock properties affect the product characteristics, which has been examined statistically using multiple linear regression (MLR) technique in this study. Good agreement has been observed between the results from the analysis of variance (ANOVA) and those reported by the experiments. The fuel properties of hydrochar were affected by the characteristics of raw sludge on different statistical significance. The HTC reaction severity combining with HTC duration or temperature was deemed statistically significant for hydrogen, oxygen, nitrogen, volatile matters and ash contents in the hydorchar, while HTC duration and HTC temperature were of statistical significance to sulfur and fixed carbon contents, respectively. However, carbon content in the hydrochar was only statistically dependent on the initial sludge properties. Subsequently, MLR models were developed based on ANOVA results, suggesting that these models fitted the data associated with hydrochar properties well in terms of correlation coefficiency > 0.8 and root mean squared error of calibration < 3%. Meanwhile, all these developed models could reasonably predict the fuel properties of hydrochar, whose values were within 10% of the corresponding experimental values. Thus, they can be adopted as a general guide or a screening tool to meet specific carbonization objective.

关键词： Sewage sludge Hydrothermal carbonization Hydrochar Multiple linear regression Reaction severity

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Simulation on alternating oscillation flow in microchannel pulse tube coupled with active piston using non-equilibrium molecular dynamics

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CHEMICAL PHYSICS LETTERS 2020年 759卷 137965-137965页

作者： Che, Yanjin Qi, Yingxia Niu, Shizhe Liu, Yali Zhang, Hua Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China

The molecular dynamics method was used to calculate the alternating oscillating flow in the micro-channel pulse tube. A thermodynamics corresponding process of the pulse tube coupled with an active piston was simulated. The simulation results show that the pressure amplitude at middle of tube was smaller than the two ends of the tube, but the main temperature gradient was distributed among them and the temperature at cold end further decreased with the motion of active piston at hot end. The optimal field distribution was obtained when the displacement phase angle for the compression piston and the active piston was 108 degrees.

关键词： Molecular dynamics simulation Microchannel pulse tube Temperature field Pressure gradient Active piston

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Physics-informed neural networks for solving forward and inverse flow problems via the Boltzmann-BGK formulation

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JOURNAL OF COMPUTATIONAL PHYSICS 2021年 447卷 110676-110676页

作者： Lou, Qin Meng, Xuhui Karniadakis, George Em Univ Shanghai Sci & Technol Sch Energy & Power Engn Shanghai 200093 Peoples R China Univ Shanghai Sci & Technol Shanghai Key Lab Multiphase Flow & Heat Transfer Shanghai 200093 Peoples R China Brown Univ Div Appl Math Providence RI 02906 USA Pacific Northwest Natl Lab Richland WA 99354 USA

The Boltzmann equation with the Bhatnagar-Gross-Krook collision model (Boltzmann-BGK equation) has been widely employed to describe multiscale flows, i.e., from the hydrodynamic limit to free molecular flow. In this study, we employ physics-informed neural networks (PINNs) to solve forward and inverse problems via the Boltzmann-BGK formulation (PINN-BGK), enabling PINNs to model flows in both the continuum and rarefied regimes. In particular, the PINN-BGK is composed of three sub-networks, i.e., the first for approximating the equilibrium distribution function, the second for approximating the non-equilibrium distribution function, and the third one for encoding the Boltzmann-BGK equation as well as the corresponding boundary/initial conditions. By minimizing the residuals of the governing equations and the mismatch between the predicted and provided boundary/initial conditions, we can approximate the Boltzmann-BGK equation for both continuous and rarefied flows. For forward problems, the PINN-BGK is utilized to solve various benchmark flows given boundary/initial conditions, e.g., Kovasznay flow, Taylor-Green flow, cavity flow, and micro Couette flow for Knudsen number up to 5. For inverse problems, we focus on rarefied flows in which accurate boundary conditions are difficult to obtain. We employ the PINN-BGK to infer the flow field in the entire computational domain given a limited number of interior scattered measurements on the velocity without using the (unknown) boundary conditions. Results for the two-dimensional micro Couette and micro cavity flows with Knudsen numbers ranging from 0.1 to 10 indicate that the PINN-BGK can infer the velocity field in the entire domain with good accuracy. Finally, we also present some results on using transfer learning to accelerate the training process. Specifically, we can obtain a three-fold speedup compared to the standard training process (e.g., Adam plus L-BFGS-B) for the two-dimensional flow problems considered in our

关键词： Boltzmann-BGK equation Physics-informed neural networks Rarefied flows Velocity slip Inverse problems transfer learning

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