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Experimental and numerical investigations of heat transfer in the first wall of Helium-Cooled-Pebble-Bed Test Blanket Module - Part 1: Presentation of test section and 3d cfd model

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FUSION ENGINEERING ANd dESIGN 2015年 90卷 29-36页

作者： Ilic, M. Messemer, G. Zinn, K. Meyder, R. Kecskes, S. Kiss, B. Karlsruhe Inst Technol Inst Neutron Phys & Reactor Technol D-76021 Karlsruhe Germany Budapest Univ Technol & Econ Inst Nucl Tech Budapest Hungary

This paper deals with cooling of the first wall of Helium-Cooled-Pebble-Bed Test Blanket Module (HCPB TBM) for ITER. The first wall cooling is an important investigation issue due to an extreme asymmetry of heat loads: heat flux on the plasma facing side is several times stronger than the one on the side which faces breeding units. Our preliminary 3d cfd analysis revealed that under such conditions the heat transfer coefficient is significantly lower than predicted by common heat transfer correlations (see Ilic et al., 2006). For an experimental validation of these results HETRA (HEat TRAnsfer)test section has been designed and built at the Institute for Neutron Physics and Reactor Technology in Karlsruhe Institute of Technology. The HETRA test section involves in full scale one U-pass of the cooling channel in the first wall of HCPB TBM Version 1.1 (see Meyder et al., 2005). The HCPB TBM relevant experimental conditions have been provided: test channel made of Eurofer steel, helium coolant at pressure of 8 MPa and inlet temperature of 300 C and heat flux of 270 kW/m(2) at the channel surface representing plasma facing side of the first wall. Test channels with hydraulically smooth and with hydraulically rough walls have been built. At each test channel the temperature of Eurofer walls has been measured at 60 positions, For numerical investigations the 3d cfd modelling with the code STAR Cd has been applied. This paper is the first report on this study and presents the development of the test section and of the 3d cfd model. The analyses of the obtained experimental and computational results are presented in the second report (see Ilic et al., 2014). 2014 Elsevier B.V. All rights reserved.

关键词： Test blanket module The first wall Heat transfer Test section 3d cfd model

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A cold start strategy in fuel cell vehicles to provide instant hot air for stacks and passengers by vortex tubes

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APPLIEd THERMAL ENGINEERING 2024年第PartA期257卷

作者： Rezaei, Amirmohammad Afshari, Ebrahim Univ Isfahan Fac Engn Dept Mech Engn Hezar Jerib Ave Esfahan *** Iran

Green vehicles, particularly Fuel Cell Vehicles (FCVs), offer a promising solution to environmental challenges. One of the major obstacles for FCVs is starting the Polymer Electrolyte Membrane (PEM) fuel cell stacks in subfreezing temperatures, where the water produced by chemical reactions can freeze and hinder the cold-start process. Preheating the inlet air to the stack up to 80 degrees C is an effective approach to overcome this issue. However, conventional heating systems, such as electric heaters, are unable to heat the air quickly enough. This paper introduces a novel heating method to enhance the cold-start capability of FCVs. The proposed solution involves integrating vortex tubes, which are simple and cost-effective, with the vehicle's existing compressor. This system not only preheats the inlet air to the stacks but also provides warm air for the passengers simultaneously. By developing a 3d-cfd model of the vortex tube, the results demonstrate that the system can preheat the inlet air to the stacks from -30 degrees C to 80 degrees C and the air entering the passenger compartment from -30 degrees C to nearly 37 degrees C in just about 5 s. In comparison, conventional heating systems require over 600 s (10 min) to achieve the same temperature rise.

关键词： Fuel cell vehicles (FCVs) Cold start strategy Passenger compartment heating system Vortex tubes 3d cfd model Transient solution

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Reliability-based retrofit assessment of coastal bridges subjected to wave forces using 3d cfd simulation and metamodeling

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CIVIL ENGINEERING ANd ENVIRONMENTAL SYSTEMS 2021年第1期38卷 59-83页

作者： Zhu, deming Li, Yaohan dong, You Shenzhen Urban Transport Planning Ctr Co Ltd Hong Kong Peoples R China Hong Kong Polytech Univ Dept Civil & Environm Engn Hong Kong Peoples R China

This paper proposes a comprehensive analysis framework, combining three-dimensional (3d) numerical modelling and metamodeling, to investigate the probabilistic performance of retrofit actions on coastal bridges subjected to extreme wave forces. Specifically, a 3d Computational Fluid dynamics (cfd) model is developed to calculate extreme wave load on the bridge superstructure. The established 3d model is validated by laboratory experiments. The characteristics of wave forces are parametrically investigated, and an Artificial Neural Network (ANN) metamodel is utilised to quantify the loading effects with multiple surge and wave parameters. Such a numerical-based ANN metamodel could predict wave forces under variable scenarios accurately, and significantly reduce the high computational cost of the 3d numerical model. Based on the numerical and metamodeling results, the bridge fragility curve is derived by considering uncertainties associated with structural demand, capacity, and hurricane hazard. Long-term failure risk is assessed under different climate change scenarios. Furthermore, different retrofit methods to improve structural performance and reduce failure risk are examined according to the proposed framework, including inserting air venting holes, enhancing connection strengths, and elevating bridge structures. The proposed framework could facilitate the optimal and robust design and maintenance of coastal infrastructures under hurricane effects in a long-term time interval.

关键词： Coastal bridge 3d cfd model Retrofit Artificial Neural Network Climate change Probabilistic fragility model

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Coupling cfd model and FEM model to investigate the impact of debris flows on a low-rise building

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RESULTS IN ENGINEERING 2024年 24卷

作者： Le, Thi Thu Hien Nguyen, Van Chien Nguyen, duc Toan Tran, duc Thanh Thuyloi Univ Fac Water Resources Engn 175 Tay Son Dong Da 116705 Ha Noi Vietnam Hydraul Construct Inst 3-95 Chua Boc Dong Da 116705 Ha Noi Vietnam Thuyloi Univ Fac Civil Engn 175 Tay Son Dong Da 116705 Ha Noi Vietnam

This study integrates a hydrodynamic model with a structural analysis model to investigate the behavior of a reinforced concrete (RC) frame building under the influence of various hydrodynamic variables, such as debris flow materials, flow intensity, and flow direction. The impact force generated during the first phase of fluidstructure interaction is significantly larger around (20 divided by 30) % than that in the steady phase, resulting in a substantially bigger maximum value of bending moment (Mmax) and displacement (delta) in every RC column. An increase in flow intensity and solid concentration leads to a larger impact load, resulting in higher values of Mmax and delta. Furthermore, the flow that passes through the porous exterior of the house poses a greater risk than the flow that affects the non-porous side of the house. By comparison with two Vietnamese standards of bending moment and displacement, all columns of the target building are susceptible to collapse in all scenarios when taking into account the bending moment. Nevertheless, in relation to the key threshold of displacement, the building is likely to remain secure.

关键词： 3d cfd model Impact force Reinforced concrete frame building Structural analysis

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Effects of the driftwood Richardson number and applicability of a 3d-2d model to heavy wood jamming around obstacles

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ENVIRONMENTAL FLUId MECHANICS 2020年第3期20卷 503-525页

作者： Kimura, Ichiro Kitazono, Kazuya Univ Toyama Fac Sustainable Design Toyama Japan Chubu Elect Power Co Inc Nagoya Aichi Japan

Predicting the motion of driftwood around hydraulic structures such as bridge piers and spur dikes is important. We propose a numerical model for simulating driftwood motion that is based on coupling an Eulerian-type three-dimensional flow model and a Lagrangian-type two-dimensional driftwood model. Laboratory tests were carried out on the driftwood motion in a curved channel and around obstacles to obtain reference data. The computational results showed that three-dimensional flow features considerably affect the motion of driftwood in a curved channel. We defined the driftwood Richardson number (dRI) to classify the three-dimensional behavior of driftwood around obstacles. The experimental results showed that an increasing dRI indicates more three-dimensional behavior by driftwood and a decreased capture ratio by obstacles. We also developed a two-way model in which the drag force from driftwood on the flow is modeled to simulate the backwater elevation and the flow deceleration behind the stacked driftwood. The computational results showed that the two-way model could reproduce the increase of water level and the decrease of velocity at the upstream region of the obstacles. However, such effects caused by the driftwood jamming were underestimated if the jamming happened in a three-dimensional manner.

关键词： driftwood Wood jamming 3d cfd model discrete element method driftwood Richardson number (dRI)

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development of a cfd model and procedure for flows through in-stream structures

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JOURNAL OF APPLIEd WATER ENGINEERING ANd RESEARCH 2022年第3期10卷 197-211页

作者： Lai, Yong G. Smith, david L. Bandrowski, david J. Xu, Yuncheng Woodley, Christa M. Schnell, Kaitlin US Bur Reclamat Tech Serv Ctr Denver CO 80225 USA US Army Corps Engineers Engineer Res & Dev Ctr Vicksburg MS 39180 USA Yurok Tribe Fisheries Div Weaverville CA USA China Agr Univ Coll Water Resources & Civil Engn Beijing Peoples R China US Army Corps Engineers Seattle WA USA

Y Large wood (LW) has been widely used in river restoration projects due to its ecological benefit. 3d modeling has rarely been conducted. In this study, a 3d modeling procedure is proposed and a new 3d model is developed. The model incorporates advanced cfd techniques and is easy to apply. An engineered log jam (ELJ) is constructed and an experiment is conducted. The data are used to demonstrate the procedure and validate the cfd model. A comparison of the predicted and measured velocity shows that agreement is good with the Nash-Sutcliffe coefficient about 0.4 and index of agreement about 0.85. The model is further applied to a curved channel with ELJ on the outer bank, demonstrating the use of the 3d model to guide the proper representation of ELJs in a 2d model. The 3d model may be used to reveal complex flow patterns generated by LW for ecological benefit analysis.

关键词： 3d cfd model URANS unstructured mesh engineered log jam large wood

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Effect of exhaust gas recirculation and compression ratio on combustion characteristics and NOx emissions in an NH3/H2O2 fueled HCCI engine

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ENERGY CONVERSION ANd MANAGEMENT-X 2025年 26卷

作者： Ali, Kabbir Mohammedali, Abubaker A. M. Ali, Mohamed I. Hassan Khalifa Univ Coll Engn & Phys Sci Mech & Nucl Engn Dept POB 127788 Abu Dhabi U Arab Emirates

This study investigates the impact of exhaust gas recirculation (EGR) and compression ratio (CR) on the combustion characteristics and NOx emissions of an NH3/H2O2-fueled homogeneous charge compression ignition (HCCI) engine. Utilizing both 3d Computational Fluid dynamics (cfd) and 1d-Chemkin-Pro models, the research explores the effects of varying NH3 and H2O2 mixtures to optimize engine performance and emissions. The study reveals that increasing EGR from 0 % to 40 % resulted in a reduction of in-cylinder pressure and HRR, particularly at a 20 % H2O2 volume fraction. At higher H2O2 concentrations (30 % and 40 %), the diluting effects of EGR were less pronounced. NOx emissions decreased significantly with increased EGR, with a reduction in peak combustion temperatures by approximately 25-65 K, leading to a decrease in NOx emissions by about 3 %. Reducing the CR from 17.1 to 14.2 led to a decrease in in-cylinder pressure and temperature, which in turn reduced the maximum pressure rise rate and NOx emissions. NOx emissions decreased by approximately 50 %, 12 %, and 8 % when the CR was reduced from 17.1 to 14.2 at H2O2 contents of 20 %, 30 %, and 40 %, respectively. Output power increased from 2.63 kW to 10.6 kW at an H2O2 volume fraction of 20 %, while at a higher H2O2 concentration of 40 %, it rose from 12.4 kW to 13.9 kW. Brake thermal efficiency and indicated thermal efficiency decreased with increasing EGR, but higher H2O2 concentrations helped sustain efficiency levels close to 50 % even under high EGR conditions. The findings highlight the potential of NH3/H2O2 as an alternative fuel, with EGR and CR adjustments offering substantial benefits in reducing emissions and enhancing engine adaptability. This research supports the development of sustainable combustion technologies that comply with stringent environmental standards.

关键词： HCCI engine Kinetic modeling 3d cfd model EGR CR

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Mass shedding rate of an isolated high-speed slug propagating in a pipeline

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ENGINEERING APPLICATIONS OF COMPUTATIONAL FLUId MECHANICS 2024年第1期18卷

作者： Fan, Huaicheng Hou, Qingzhi Tijsseling, Arris S. Sun, Xinjian Lian, Jijian Tianjin Univ State Key Lab Hydraul Engn Intelligent Construct & Tianjin 300350 Peoples R China Qinghai Minzu Univ Sch Civil & Transportat Engn Xining Peoples R China Eindhoven Univ Technol Dept Math & Comp Sci Eindhoven Netherlands Qinghai Univ Sch Hydraul & Elect Engn Xining Peoples R China

An isolated liquid slug in the pipeline can accelerate and achieve a high speed when subjected to a driving pressure. during the slug's high-speed movement in a pipeline, part of the liquid will shed from it resulting in changes in the slug's mass and length. To understand the mass shedding mechanism, the mass shedding rate is studied using three-dimensional computational-fluid-dynamics methodology, in which the volume-of-fluid technique is applied to track the water-air interface and the RNG $ k - \varepsilon $ k-epsilon model is used to describe the turbulence. The effects of driving pressure, initial slug length, pipe inclination angle, pipe wall roughness and gravity on the slug mass shedding rate are investigated. The results show that the slug mass shedding rate is independent of driving pressure, initial slug length, pipe inclination angle and gravity, and it increases as a power function with the increase in wall roughness. It is explained from the mass shedding rate that when the slug's traveled distance exceeds six times the initial slug length, the slug will break up. This paper solves the problem that there is no standard to select a reliable mass shedding rate for modeling the isolated high-speed slug propagating in *** the movement of an isolated liquid slug propelled by pressurized air with 3d cfd *** a model for calculating the slug mass shedding *** three influence factors of the slug mass shedding rate.

关键词： 3d cfd model liquid slug motion mass shedding rate holdup

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PM₁₀ dispersion modeling by means of cfd 3d and Eulerian-Lagrangian models: Analysis and comparison with experiments 71

PM<sub>10</sub> Dispersion Modeling by means of CFD 3D and E...

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71st Conference of the Italian-Thermal-Machines-Engineering-Association (ATI)

作者： Brusca, S. Famoso, F. Lanzafame, R. Mauro, S. Messina, M. Strano, S. Univ Messina I-98166 Messina Italy Univ Catania V A Doria 6 I-95125 Catania Italy

This research deals with the analysis of the dispersion of PM10 by using fluid-dynamic simulation framework. Firstly, an experimental campaign was made in a wind tunnel. A cylindrical emitter of PM10 was characterized in terms of PM10 mass flow rate and outlet velocity. It was positioned in the wind tunnel chamber where several sensors were also placed downwind. The use of different sensor configurations allowed the evaluation of the PM10 concentrations in several locations. The experimental campaign was reproduced in ANSYS-Fluent, by recreating in design-model, a 3d geometries of the test case. different calculation grids were tested in order to find the proper balance between computing time and accuracy. The cfd 3d model was based on the Eulerian approach for the continuous phase and Lagrangian approach for the dispersion phase setting the dPM for the evaluation and dispersion of particulate matters. The turbulence was solved by using a k-epsilon RANS approach and a quite advanced unsteady dES model. Several simulations were carried out by varying the flow inlet velocities in configurations with and without obstacles. The results obtained from the post-processing phase were then compared with the experimental campaign. With obstacles a PM concentration increment is observed at all imposed air velocity because of recirculation phenomena generated around the obstacles. (C) 2016 The Authors. Published by Elsevier Ltd.

关键词： 3d cfd model Eulerian/Lagrangian particle dispersion model air pollution aerosol particles

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3d electro-thermal modelling and experimental validation of lithium polymer-based batteries for automotive applications

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INTERNATIONAL JOURNAL OF ENERGY RESEARCH 2016年第8期40卷 1144-1154页

作者： daud, Zul Hilmi Che Chrenko, daniela dos Santos, Fabien Aglzim, El-Hassane Keromnes, Alan Le Moyne, Luis Univ Teknol Malaysia Fac Mech Engn Skudai 81310 Johor Malaysia Univ Bourgogne Franche Compte Id Mot DRIVE EA 1859 F-58000 Nevers France

This article presents an electro-thermal model of a stack of three lithium ion batteries for automotive applications. This tool can help to predict thermal behaviour of battery cells inside a stack. The open source software OpenFOAM provides the possibility to add heat generation because of Joule losses in a cfd model. Heat sources are introduced at the connectors and are calculated as a function of battery discharge current and internal resistance. The internal resistance is described in function of temperature. Simulation results are validated against experimental results with regard to cooling air flow field characteristic and thermal behaviour of the cell surface. The validation shows that the simulation is capable to anticipate air flow field characteristics inside the battery box. It also predicts correctly the thermal behaviour of the battery cells for various discharge rates and different cooling system conditions. The simulation supports the observation that batteries have a higher temperature close to the connectors and that the temperature increase depends highly on discharge rate and cooling system conditions. Copyright (C) 2016 John Wiley & Sons, Ltd.

关键词： 3d cfd model electric and hybrid vehicle electro-thermal modelling lithium ion battery particle image velocimetry (PIV)

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