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Development and validation of a transient simulation model of a full-scale PCM embedded radiant chilled ceiling

Building simulation 2023年第6期16卷 813-829页

作者： Seyedmostafa Mousavi Behzad Rismanchi Stefan Brey Lu Aye Renewable Energy and Energy Efficiency Group Department of Infrastructure EngineeringFaculty of Engineering and Information Technology(FEIT)The University of MelbourneMelbourneVIC3010Australia InvAus Pty Ltd. MelbourneVIC3000Australia

The recent significant rise in space cooling energy demand due to the massive use of air-conditioning systems has adversely changed buildings’energy use patterns globally.The updated energy technology perspectives highlight the need for innovative cooling systems to address this growing cooling demand.Phase change material embedded radiant chilled ceiling(PCM-RCC)has lately acquired popularity as they offer more efficient space cooling together with further demand-side flexibility.Recent advancements in PCM-RCC applications have increased the necessity for reliable simulation models to assist professionals in identifying improved designs and operating settings.In this study,a transient simulation model of PCM-RCC has been developed and validated using measured data in a full-scale test cabin equipped with newly developed PCM ceiling panels.This model,developed in the TRNSYS simulation studio,includes Type 399 that uses the Crank-Nicolson algorithm coupled with the enthalpy function to solve transient heat transfer in PCM ceiling panels.The developed model is validated in both free-running and active operation modes,and its quality is then evaluated using several validation metrics.The results obtained in multiple operating scenarios confirm that the model simulates the transient behaviour of the PCM-RCC system with an accuracy within±10%.Aided by this validated model,which offers the user detailed flexibilities in the system design and its associated operating schemas,PCM-RCC’s potentials regarding peak load shifting,energy savings,and enhanced thermal comfort can be investigated more reliably.

关键词： phase change material(PCM) radiant cooling ceiling panel modelling and simulation validation

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Role of hydrogen in stability and mobility of vacancy clusters in tungsten

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Tungsten 2022年第3期4卷 219-230页

作者： Hao-Xuan Huang Yu-Hao Li Zhong-Zhu Li Peng-Wei Hou Fang-Fei Ma Qing-Yuan Ren Hong-Bo Zhou Guang-Hong Lu Department of Physics Beihang UniversityBeijing100191China Beijing Key Laboratory of Advanced Nuclear Materials and Physics Beihang UniversityBeijing100191China

We investigated the influence of hydrogen(H)on the stability and mobility of small vacancy clusters in tungsten(W)using the first-principles calculations.It is found that the presence of H not only increases the binding energy of small vacancy clusters but also changes their most favorable configurations,owing to the strong attractive interaction between H and vacancies in W.Specifically,the binding energy of di-vacancy changes from negative to positive when the H atoms are introduced.These results suggest that the H addition can significantly promote the stability of small vacancy clusters in W.More importantly,although the migration energy barriers of H-vacancy(H-V)complexes are slightly higher than that of pure vacancy clusters,the activation energy required for complexes migration is always lower than that for dissociation.Therefore,contrary to the conventional view,the collaborative motion of H and small vacancy clusters is possible,because of the low migration energy barriers.Based on the energetic results obtained by first-principles calculations,the mean lifetime and mean diffusion distance of small H-V complexes at different temperatures are examined by the object kinetic Monte Carlo simulations.The small H-V complexes are found to be stable and mobile at moderate temperature,and thus may affect the co-evolution of H and vacancies.These results shed light on the important role of H on the vacancy behaviors and provide a good reference for understanding the defects evolution in W.

关键词： Tungsten Hydrogen effects Vacancy clusters Stability and mobility modelling and simulation

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Inverse design of mission success space for combat aircraft contribution evaluation

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Chinese Journal of Aeronautics 2020年第8期33卷 2189-2203页

作者： Yuan GAO Hu LIU Yongliang TIAN School of Aeronautic Science and Engineering Beihang UniversityBeijing 100083China

This paper presents a novel design method of the Mission Success Space(MSS) for the evaluation on aircraft contribution effectiveness. MSS concept was proposed for giving success criterion of a mission and judging the success by conventional mission effectiveness with regards to the aircraft capabilities. This space is created by the Mission Success Function(MSF) and the original Effectiveness Index Space(EIS) where empirical equations are usually assumed to be MSFs. Based on this MSS concept, this paper firstly defines the MSS-based evaluation, then further summarizes the evaluation process of the Contribution to System-of-Systems(CSS). More importantly, based on the thought of Inverse Design(ID), a new design method of MSF is presented comprehensively analyzing aircraft's CSS in a combat mission without using any empirical MSF. The definition of MSS based ID is given and the design procedure is sequentially introduced. Two different confrontation cases are depicted with many details as the simulation validation: Air-to-ground and Penetration. There are two design variables considered for designing MSS in the latter case while only one for the former. However, in both cases, the best design is given by evaluating the Gaussian fitting performance of CSS.

关键词： Contribution effectiveness Effectiveness evaluation Gaussian fitting Inverse design Military missions modelling and simulation Success rate System of systems

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High adsorption and separation performance of CO_(2) over N2 in azo-based(N=N)pillar[6]arene supramolecular organic frameworks

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Chinese Physics B 2021年第11期30卷 625-631页

作者：姜永超李桂霞于桂凤王娟黄树来徐国亮 College of Science and Information Qingdao Agricultural UniversityQingdao 266109China School of Physics Henan Normal UniversityXinxiang 453007China

Azo-based pillar[6]arene supramolecular organic frameworks are reported for CO_(2) and N_(2) adsorption and separation by density functional theory and grand canonical Monte–Carlo simulation.Azo-based pillar[6]arene provides suitable environment for CO_(2) adsorption and selectivity.The adsorption and selectivity results show that introducing azo groups can effectively improve CO_(2) adsorption and selectivity over N_(2),and both CO_(2) adsorption and CO_(2) selectivity over N_(2) follow the sequence pillar[6]arene N_(4)>pillar[6]arene N2>pillar[6]arene.Pillar[6]arene N_(4) exhibits CO_(2) adsorption capacity of1.36 mmol/g,and superior selectivity of CO_(2) over N_(2) of116.75 with equal molar fraction at 1 bar(1 bar=105 Pa)and 298 K.Interaction analysis confirms that both the Coulomb and van derWaals interactions between CO_(2) with pillar[6]arene frameworks are greater than that of N_(2).The stronger affinity of CO_(2) with pillar[6]arene N_(4) than other structures and the larger isosteric heat differences between CO_(2) and N2 rendered pillar[6]arene N4 to present the high CO_(2) adsorption capacity and high CO_(2) selectivity over N_(2).Our results highlight the potential of azo-functionalization as an excellent means to improve pillar[6]arene for CO_(2) capture and separation.

关键词： supramolecular organic framework functionalization modelling and simulation carbon capture and storage

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Research in Moisture Transport through One and Two-layered Porous Composites

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International Journal of Automation and computing 2005年第1期2卷 93-100页

作者： Kemal Ahmet Luton Institute of Research in Applied Natural Science University of Luton

Research into the moisture transport processes in porous materials is primarily important for theoretical modelling and industrial applications in the design of energy saving buildings and living environments, etc. Based on experimental investigation, we propose new models which describe one-dimensional transport through one-layered uniform materials and dissimilar two-layered composites. Diffusivity as a function of moisture content is obtained through a Boltzman transformation, master curves, and combined numerical and regression techniques. Transport processes in one and two-layered composites are simulated on the basis of extended unsaturated Darcy’s Law using the finite element method (FEM). simulation results show significantly different transport patterns of moisture profile when moisture migrates in different directions, and high agreement with experimental moisture profiles. Keywords Porous materials - moisture transport - two-layered composites - modelling and simulation Qingguo Wang graduated from Hebei Normal University, China, in 1985. He received the M.Sc. degree from Beijing Petroleum University in 1988 and the Ph.D. degree from the University of Luton, UK, in 2005. He is currently a Research Associate in the Department of Electrical Engineering and Electronics at the University of Liverpool, UK and an Associate Professor of Shijiazhuang Mechanical Engineering College, China. His research interests include measurement and control, mass and heat transportation, EMC, etc.Kemal Ahmet graduated in physics from the University of Leeds. Following the completion of his masters degree, he completed his Ph.D. at the University of London in the area of nuclear instrumentation in 1992. Until recently, he was a Principal Lecturer at the University of Luton, leading a research group in moisture instrumentation, measurement and monitoring. In 2004 he joined Medtronic, world leader in medical technology, and is currently working in the Neurologic Technologies division as a specialist in powered surgical in

关键词： Porous materials moisture transport two-layered composites modelling and simulation

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Analysis of Higher Order System with Impulse Exciting Functions in Z-Domain

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Circuits and Systems 2016年第11期7卷 3951-3970页

作者： Branislav Dobrucký Pavol Štefanec Mariana Beňová Oleg V. Chernoyarov Michal Pokorný Faculty of Electrical Engineering University of ?ilina ?ilina Slovak Republic Department of Radio Engineering Devices and Antenna Systems National Research University Moscow Power Engineering Institute Moscow Russia

This paper deals with mathematical modelling of impulse waveforms and impulse switching functions used in electrical engineering. Impulse switching functions are later investigated using direct and inverse z-transformation. The results make possible to present those functions as infinite series expressed in pure numerical, exponential or trigonometric forms. The main advantage of used approach is the possibility to calculate investigated variables directly in any instant of time;dynamic state can be solved with the step of sequences (T/6, T/12) that means very fast. Theoretically derived waveforms are compared with simulation worked-out results as well as results of circuit emulator LT spice which are given in the paper.

关键词： Impulse Systems Switching Function Z-Transformation Inverse Z-Transformation Steady State Operation Dynamical State Model modelling and simulation

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搅拌摩擦焊并联机床静态特性分析

搅拌摩擦焊并联机床静态特性分析

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作者： Brian Nurimba 哈尔滨工业大学

学位级别：硕士

Friction stir welding (FSW) is a solid-state welding technique. So, it doesn’t involve material melting in the process. This process is quiet popular, especially in aircraft and space vehicle manufacturing industry since it can weld lightweight aluminium alloy with a very good quality. However, the understanding of the welding process condition is still not enough to predict the weld quality and the impact it has to the machine tool’s stiffness in different welding parameters. Since manufacturing companies want to increase productivity without too many additional cost (adding a new production line, etc.), so naturally they want to increase the welding speed, etc. However, changing the welding parameter probably will cause the weld quality drop since there is not enough heat input to the weld, etc. So, the understandingof the welding process in depth is essential.In this thesis a FEM simulation to obtain the forces and temperature during the FSW process has been conducted. The modelling and simulation were conducted in DEFORM3D software. The workpiece which is being welded for the FSW process were modeled as one workpiece in order to avoid contact instabilities during simulation. No movement boundary condition has been placed on the workpiece. The convection to the environment is the only boundary condition. However the simulation result is not good enough to be used in the next step, which is to apply the forces to the design of machine tool’s assembly in order to get the resulting stress and deformation of the design using static structural analysis of Ansys Workbench. But still, the static structural analysis was still conducted using the known maximum force value. This maximum force value was given by the welding company, which propose for this project, based on the welding company’s experience. And the result is the stress received by machine tool’s are still below the tensile yield strength of the material. However the maximum deformation exceeds a little from the required specification of the machine to

关键词： friction stir welding (FSW) modelling and simulation 5-axis parallelkinematic structure static analysis

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