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Numerical Simulation of the Odor Spreading in a Factory
Lijo Vincent,Eun-Hwa Song(송은화),Hyun-Kyu Nam(남현규),Choon-Sik Shin(신춘식),Heuy-Dong Kim(김희동) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11
Liquid crystal displays (LCD's) are continuously coated with some chemicals in the clean room of a factory. Spreading of these chemicals is causing serious problems both in controlling clean room quality as well as to the workers inside the factory. It is required to alleviate or properly control the offensive odor which is mainly composed of propylene glycol mono ethyl acetate, novolak resin and photo active compound. The control strategy employed is to bleed the offensive odor gas out the clean room. A full scale 3D CFD model was created with anisotropic porous media, chemical species transport with no volumetric reaction, and thermal diffusion with propane gas (tracer gas) to simulate the odor spreading. A segregated implicit solver with standard k-ε model is employed. The detailed CFD analysis made it possible to develop an effective method of ventilating the coater room and optimizing their capacities.
진공 이젝터-디퓨져 시스템내의 비정상 유동 과정에 관한 연구
Lijo Vincent,김희동(Heuydong Kim),T.Setoguchi 한국추진공학회 2009 한국추진공학회 학술대회논문집 Vol.2009 No.5
The objective of the present study is to analyze the transient flow through theejector system with the help of a computational fluid dynamics (CFD) method. An attempt is made to investigate the interesting and conflicting phenomenon of the infinite entrainment into the primary stream without an infinite mass supply from the secondary chamber. The results obtained show that the one and only condition in which an infinite mass entrainment can be possible in such types of ejectors is the generation of a re-circulation zone near the primary nozzle exit. The flow in the secondary chamber attains a state of dynamic equilibrium of pressures at the onset of the recirculation zone. A steady flow in the ejector system is valid only after this point.
Vincent Lijo,김희동(Heuy Dong Kim) 한국추진공학회 2011 한국추진공학회 학술대회논문집 Vol.2011 No.5
Supersonic ejectors are simple mechanical components, which generally perform mixing and recompression of two fluid streams. Ejectors have found many applications in engineering. In aerospace engineering, they are used for high altitude testing (HAT) of a propulsion system by reducing the pressure of a test chamber. It is composed of three major sections: a vacuum test chamber, a propulsive nozzle, and a supersonic exhaust diffuser (SED). This paper aims at the improvement in HAT facility by focusing attention on the vertical firing rocket test stand with shock generators. Shock generators are mounted inside the SED for improving the pressure recovery. The results clearly showed that the performance of the ejector-diffuser system was improved with the addition of shock generators. The improvement comes in the form of reduction of the starting pressure ratio and the vertical height of test stand. It is also shown that shock generators are useful in reducing the total pressure loss in the SED.
Numerical Study on the Compressible Internal Flow with Heat Transfer
Vincent Lijo,Heuy-Dong Kim(김희동) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.4
Compressible gas flows with heat transfer effects from wall surface are frequently encountered in many practical engineering applications. In the present study, numerical simulations have been used to provide a detailed description of compressible flows in a straight duct with heat transfer. The numerical model is validated with some experimental data of compressible flow through a straight duct. The equations solved are the steady, 3D RANS with standard k-eo turbulence model. The validated model is used to study the effects of different thermal wall boundary conditions such as adiabatic, isothermally heated and cooled walls, to show in detail those regions where the flow is two-dimensional, and thus where the simple one-dimensional flow prediction fails.
Solar PV and Wind Energy Based Reconfigurable Microgrid for Optimal Load Dispatch
Varghese Lijo Jacob,Arun Kumar U.,Sunitha D. 대한전기학회 2023 Journal of Electrical Engineering & Technology Vol.18 No.4
Distribution generation (DG), energy storage systems (ESS), distributed reactive sources (DRS), and resilient loads that may operate in both linked and isolated modes form the microgrid (MG). Unpredictable and variable DGs, like as renewable energy sources like wind and photovoltaic systems, are especially difficult for MG planners to make judgments on (PVES). This work provides a rigorous hybrid optimization approach for designing reconfigurable MGs to tackle technological and economic uncertainty. The suggested technique leverages the moth flame optimization (MFO) algorithm paired with a heuristic fuzzy for optimum DG positioning and reconfiguration, manufacturing costs, and loss avoidance. This hybrid algorithm improves electricity quality, increases customer savings, and benefits the distributed system operators (DSO). The MFO algorithm is used to optimize and reorganize DG sites, and the fuzzy technique is utilized to deal with multi-objective problems, all to reduce microgrid expenses like emission costs and the supply of reliable energy. Using the supplied technique to address three distinct situations helps DSO choose the appropriate structures. For testing, a 33-bus IEEE RDS microgrid is employed. Validation is done utilizing a 24-h daily load pattern and 24-h typical load dispatching behavior for both WES and PVES to ensure reliability. Studies show micro grids outperform present structures.
Vincent Lijo,Heuy-Dong Kim 한국추진공학회 2013 한국추진공학회 학술대회논문집 Vol.2013 No.12
In order to obtain insight into the physics of micro-nozzle flows, numerical simulations of rarefied flows in a convergent-divergent micro-nozzle is investigated by using the Direct Simulation Monte Carlo (DSMC) method. This method can be applied to a wide range of rarefied flows within regimes that neither Navier-Stokes nor collisionless Boltzmann equations are appropriate. In the present work, the molecular collision kinetics is modeled by the variable hard sphere model and energy exchange between kinetic and internal modes is controlled by the phenomenological Larsen- Borgnakke statistical model. Simulations are performed by considering a non-reacting gas model consisting of two chemical species, N2 and O2 for various back pressures and results are presented for the computed flow field quantities. Comparisons are made with the available experimental data, and the factors which affect the solutions are discussed. This study revealed that in micro-nozzles surface effects play the main role on the flow structure. Separate calculations are also performed for the “macro-nozzle” flows and detailed comparisons between typical rarefied and continuum behaviors are made.
Numerical investigation of transient side-loads in the start-up process of a rocket nozzle
Vincent Lijo,김희동,Toshiaki Setoguchi,Shigeru Matsuo 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.2
A numerical investigation of transient side-loads in axisymmetric over-expanded thrust optimized contour nozzles is presented. These nozzles experience side-loads during start-up and shut-down operations because of flow separation at the nozzle walls. Two types of flow separations, FSS and RSS shock structures, also occur. A two-dimension numerical simulation was carried out over axisymmetric TOC nozzles to validate the present results and investigate oscillatory flow characteristics for start-up processes. Reynolds Averaged Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme. Governing equations are solved via the coupled implicit scheme. The Reynolds Stress turbulence model is selected for this work. It was found that the present computed pressure at the nozzle walls closely matched the experimental data. The phenomenon of hysteresis was also observed between these two shock structures. The transition from an FSS to RSS pattern during the start-up process showed maximum nozzle wall pressure and fluctuations in shear stress values. Oscillatory pressure was observed on the nozzle walls with high pressure ratio. The present results show that the magnitude of nozzle wall pressure variation is high for the phenomenon of oscillation.