• Title/Summary/Keyword: thermal and dynamic modeling

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A Magnetic Suspension Stage Based on the Switched Reluctance Propulsion Principle (Switched Reluctance 추진 원리에 기초한 자기 부상형 위치결정기구)

  • Lee Sang-Heon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.30 no.6 s.249
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    • pp.622-630
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    • 2006
  • This paper is about the magnetic suspension stage based on the Switched Reluctance propulsion principle. Because the previous studies on contact-free stage adopted the Lorentz force for main force generation mechanism they have suffered from thermal problem deteriorating the precision. Thus, the magnetic suspension stage adopting SR principle which can achieve high force density is proposed. The main operating principle and structure for achieving high resolution and long travel range are represented. The magnetic force analysis of each actuator, providing back data for dynamic modeling and controller design are carried out. By conducting basic experiments, the feasibility of the proposed system is shown. In addition the problems which should be improved and their solutions are represented.

OLED display manufacturing by Organic Vapor Phase Deposition

  • Marheineke, B.
    • 한국정보디스플레이학회:학술대회논문집
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    • 2006.08a
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    • pp.1676-1681
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    • 2006
  • We report on Organic Vapor Phase Deposition $(OVPD^{(R)})$ an innovative deposition technology for organic light emitting device (OLED) and organic semiconductor manufacturing. The combination of $OVPD^{(R)}$ with Close Coupled Showerhead (CCS) technology results in manufacturing equipment with vast potential for cost effective manufacturing of OLED displays commercially competitive to LCD. The actual $OVPD^{(R)}$ equipment concept and design is discussed: Computational Fluid Dynamic (CFD) modeling is compared with experimental results proving the excellent controllability of the deposition process. Further other production relevant deposition properties are being reviewed e.g. high deposition rates and high organic material utilization efficiency of the $OVPD^{(R)}$ - Technology. Data from devices made by $OVPD^{(R)}$ show comparable/ superior performance to those fabricated with conventional vacuum thermal evaporation (VTE) techniques. An outlook on further potentials of $OVPD^{(R)}$ with respect to enabling advanced organic device structures is given.

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Direct Power Control Scheme of Improved Command Tracking Capability for PMSG MV Wind turbines

  • Kwon, Gookmin;Suh, Yongsug
    • Proceedings of the KIPE Conference
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    • 2015.07a
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    • pp.361-362
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    • 2015
  • This paper proposes a Direct Power Control (DPC) scheme of improved command tracking capability for Permanent Magnet Synchronous Generator (PMSG) Medium Voltage (MV) Wind Turbines. Benchmarking is performed based on a neutral point clamped three-level back-to-back type voltage source converter. It is introduced to design the DPC modeling and propose DPC scheme of a three-level NPC (3L-NPC) converter. During the fault condition in wind farms, the proposed control scheme directly controls the generated output power to the command value from the hierarchical wind farm controller. The proposed control scheme is compared with conventional control scheme as respect to loss and thermal analysis. The DPC scheme of improved command tracking capability is confirmed through PLECS simulations. Simulation result shows that proposed control scheme achieves a much shorter transient time in a step response of generated output power. The proposed control scheme makes it possible to provide a good dynamic performance for PMSG MV wind turbine to generate a high quality output power under grid fault condition.

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An Analysis of Dynamic Characteristics of RDX Combustion Using Rigorous Modeling (상세 모델링을 통한 RDX 연소 동특성 분석)

  • Kim, Shin-Hyuk;Yeom, Gi-Hwoen;Moon, Il;Chae, Joo-Seung;Kim, Hyeon-Soo;Oh, Min
    • Clean Technology
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    • v.20 no.4
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    • pp.398-405
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    • 2014
  • In the treatment of spent high energetic materials, the issues such as environmental pollution, safety as well as working capacity should be carefully considered and well examined. In this regard, incineration has been recommended as one of the most promising processes for the disposal of such explosives. Due to the fact that high energetic materials encompass various types and their different characteristics, the technology development dealing with various materials is not an easy task. In this study, rigorous modeling and dynamic simulation was carried out to predict dynamic physico-chemical phenomena for research department explosive (RDX). Plug flow reactor was employed to describe the incinerator with 263 elementary reactions and 43 chemical species. Simulation results showed that safe operations can be achieved mainly by controlling the reactor temperature. At 1,200 K, only thermal decomposition (combustion) occurred, whereas increasing temperature to 1,300 K, caused the reaction rates to increase drastically, which led to ignition. The temperature further increased to 3,000 K which was the maximum temperature recorded for the entire process. Case studies for different operating temperatures were also executed and it was concluded that the modeling approach and simulation results will serve as a basis for the effective design and operation of RDX incinerator.

Effective study of operating parameters on the membrane distillation processes using various materials for seawater desalination

  • Sandid, Abdelfatah Marni;Neharia, Driss;Nehari, Taieb
    • Membrane and Water Treatment
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    • v.13 no.5
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    • pp.235-243
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    • 2022
  • The paper presents the effect of operating temperatures and flow rates on the distillate flux that can be obtained from a hydrophobic membrane having the characteristics: pore size of 0.15 ㎛; thickness of 130 ㎛; and 85% porosity. That membrane in the present investigation could be the direct contact (DCMD) or the air-gap membrane distillation (AGMD). To model numerically the membrane distillation processes, the two-dimensional computational fluid dynamic (CFD) is used for the DCMD and AGMD cases here. In this work, DCMD and AGMD models have been validated with the experimental data using different flows (Parallel and Counter-current flows) in non-steady-state situations. A good agreement is obtained between the present results and those of the experimental data in the literature. The new approach in the present numerical modeling has allowed examining effects of the nature of materials (Polyvinylidene fluoride (PVDF) polymers, copolymers, and blends) used on thermal properties. Moreover, the effect of the area surface of the membrane (0.021 to 3.15 ㎡) is investigated to explore both the laminar and the turbulent flow regimes. The obtained results found that copolymer P(VDF-TrFE) (80/20) is more effective than the other materials of membrane distillation (MD). The mass flux and thermal efficiency reach 193.5 (g/㎡s), and 83.29 % using turbulent flow and an effective area of 3.1 ㎡, respectively. The increase of feed inlet temperatures and its flow rate, with the reduction of cold temperatures and its flow rate are very effective for increasing distillate water flow in MD applications.

A Study on Basic Modeling Method for MTF Analysis of Observation Satellites (관측위성의 MTF 해석을 위한 기본 모델링 기법 연구)

  • Kim, Do-Myung;Kim, Deok-Ryeol;Kim, Nak-Wan;Suk, Jin-Young;Kim, Hee-Seob;Kim, Gyu-Sun;Hyun, Young-Mok
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.5
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    • pp.472-482
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    • 2008
  • A modulation transfer function(MTF) tree is established to estimate the overall MTF of an observation satellite and to analyze the image performance. Basic MTF models relevant to each MTF tree component are represented as mathematical relationship between optics-structural dynamics, thermal deformation, attitude and dynamic characteristics of a satellite and the effects due to the space environment. The Basic MTF models consist of diffraction limited MTF with central obscuration, aberration, defocus, line-of-sight(LOS) jitter, linear motion, detector integration, and so forth. Performance estimation is demonstrated for a virtual earth-observation satellite in order to validate the constructed modeling method. The proposed models enable the system engineers to calculate the overall system MTF and to determine the crucial design parameters that affect the image performance in the conceptual design phase of an observation satellite.

Thermal Memory Effect Modeling and Compensation in Doherty Amplifier (Doherty 증폭기의 열 메모리 효과 모델링과 보상)

  • Lee Suk-Hui;Lee Sang-Ho;Bang Sung-Il
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.42 no.9 s.339
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    • pp.49-56
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    • 2005
  • Memory effect, which influence the performance of Doherty amplifier, become more significant and critical in designing these circuits as the modulation signal bandwidth and operation power level increase. This paper reports on an attempt to investigate, model and quantity the contribution of the electrical nonlinearity effects and the thermal memory effects to a Doherty amplifier's distortion generation. Also this raper reports on the development of an accurate dynamic expression of the instantaneous junction temperature as a function of the instantaneous dissipated power. This expression has been used in the construction of an electrothermal model for the Doherty amplifier. Parameters for the nelv proposed behavior model were determined from the Doherty amplifier measurements obtained under different excitation conditions. This study led us to conclude that the effects of the transistor self-heating phenomenon are important for signals with wideband modulation bandwidth(ex. W-CDMA or UMTS signal). Doherty amplifier with electrothermal memory effect compensator enhanced ACLR performance about 20 dB than without electrothemal memory effect compensator. Experiment results were mesured by 60W LDMOS Doherty amplifier and electrothermal memory effect compensator was simulated by ADS.

Dynamic thermal Design of a 1-ton Class Bio-Hydrogen Production System Simulator Using Industrial Waste Heat and by-Products (산업배열 및 부산물을 활용한 1톤급 바이오수소 생산 시뮬레이터 동적 열설계)

  • Kim, Hyejun;Kim, Seokyeon;Ahn, Joon
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.5
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    • pp.259-268
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    • 2017
  • This paper proposes a hydrogen-based social economy derived from fuel cells capable of replacing fossil fuels and resolving global warming, It thus provides an entry for developing economically feasible social configurations to make use of bio-hydrogen production systems. Bio-hydrogen production works from the principle that microorganisms decompose water in the process of converting CO to $CO_2$, thereby producing hydrogen. This study parts from an analysis of an existing 157-ton class NA1 bio-hydrogen reactor that identifies the state of feedstock and reactor conditions. Based on this analysis, we designed a 1-ton class bio-hydrogen reactor process simulator. We carried out thermal analyses of biological heat reactions, sensible heat, and heat radiation in order to calculate the thermal load of each system element. The reactor temperature changes were determined by modeling the feed mixing tank capacity, heat exchange, and heat storage tank. An analysis was carried out to confirm the condition of the feed mixing tank, heat exchanger, heat storage tank capacity as well as the operating conditions of the system so as to maintain the target reactor temperature.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

Modeling of the lifetime prediction of a 12-V automotive lead-acid battery (차량용 납축전지의 수명 예측 모델링)

  • Kim, Sung Tae;Lee, Jeongbin;Kim, Ui Seong;Shin, Chee Burm
    • Journal of Energy Engineering
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    • v.22 no.4
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    • pp.338-346
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    • 2013
  • The conventional lead acid battery is optimized for cranking performance of engine. Recently electric devices and fuel economy technologies of battery have influenced more deep cycle of dynamic behavior of battery. I also causes to reduce battery life-time. This study proposed that aging battery model is focused for increasing of battery durability. The stress factors of battery aging consist of discharge rate, charging time, full charging time and temperature. This paper considers the electrochemical kinetics, the ionic species conservation, and electrode porosity. For prediction of battery life cycle we consider battery model containing strong impacts, corrosion of positive grid and shedding. Finally, we validated that modeling results were compared with the accelerated thermal measurement data.