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음향 가진된 층류 비예혼합 분류 화염에서 거대 와류 거동에 관한 가시화 연구
이기만,오세기,박정,Lee, Kee-Man,Oh, Sai-Kee,Park, Jeong 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.3
A visualization study on the effect of forcing amplitude in tone-excited jet diffusion flames has been conducted. Visualization techniques are employed using optical schemes. which are a light scattering photography. Flame stability curve is attained according to Reynolds number and forcing amplitude at a fuel tube resonant frequency. Flame behavior is globally grouped into two from attached flame to blown-out flame according to forcing amplitude: one sticks the tradition flame behavior which has been observed in general jet diffusion flames and the other shows a variety of flame modes such as the flame of a feeble forcing amplitude where traditionally well-organized vortex motion evolves, a fat flame. an elongated flame. and an in-burning flame. Particular attention is focused on an elongation flame. which is associated with a turnabout phenomenon of vortex motion and on a reversal of the direction of vortex roll-up. It is found that the flame length with forcing amplitude is the direct outcome of the evolution process of the formed inner flow structure. Especially the negative part of the acoustic cycle under the influence of a strong negative pressure gradient causes the shapes of the fuel stem and fuel branch part and even the direction of vortex roll-up to dramatically change.
최석호(Seok-Ho Choi),오세기(Sai-Kee Oh),김현종(Hyun-Jong Kim),진근호(Geun-Ho Jin),오시영(Si-Young Oh),김병순(Byung-Soon Kim) 대한설비공학회 2011 설비공학 논문집 Vol.23 No.11
The aerodynamic and aeroacoustic performance of discharge grille of outdoor unit of air-conditioner was investigated in this study. Discharge grille is one of outdoor unit’s important parts to affect the flow rate and Overall Sound Pressure Level(OSPL). New type of discharge grille was suggested based on the results of numerical simulation. To simulate the flow pattern near the propeller fan, commercial flow solver FLUENT was used. Sliding mesh method was used for rotating propeller fan and initial condition for unsteady model was calculated by Multiple Reference Frame(MRF) method. To minimize the interaction noise between fan blade wake and discharge grille, new discharge grille has radial rib which is aligned with trailing edge of fan blade. And inclined radial rib was adopted for reducing flow rate drop in discharge grille. The optimization of inclined angle of radial grille was performed experimentally.
듀얼 루버를 적용한 천장형 실내기의 성능 및 기류 개선에 관한 연구
황본창(Bon Chang Hwang),서범수(Beom Soo Seo),윤필현(Phil Hyun Yoon),오세기(Sai Kee Oh) 대한설비공학회 2019 대한설비공학회 학술발표대회논문집 Vol.2019 No.11
본 논문은 카세트 실내기의 기류 성능 개선을 위해 신규 듀얼 루버를 설계 및 적용하여 성능 및 실사용 환경에서의 개선 효과를 확인한 내용을 포함하고 있다. 기존 단일 루버 구조에서는 냉방 운전 조건에서 간접 기류를 구현하기 위해 루버의 개방 단계를 낮추게 되는데 이로 인해 토출 면적의 감소하게 되어 송풍 성능이 저하되는 문제점이 있었다. 본 연구에서는 냉방 시 풍량 감소로 인한 성능 저하를 최소화 하면서 간접 기류를 효과적으로 구현함과 동시에 난방 시 기류가 바닥까지 효과적으로 도달할 수 있는 가변형 듀얼 루버 구조를 제안하였으며 CFD해석을 통해 기류 쾌적성 개선을 확인하였다. 마지막으로 개선된 듀얼 루버를 제작하여 실험을 통해 간접 기류 손실을 기존 단일 루버 대비 최대 22%, 냉방 효율은 17.1% 개선되었다. 또한 실사용 환경 조건에서 냉방 속도는 32%, 난방 시상하 온도 편차는 0.3도 개선됨을 확인하였다.
세척이 가능한 원통 코일형 열교환기의 파울링 특성에 관한 연구
황준현(Jun Hyeon Hwang),나병철(Byung Chul Na),오세기(Sai Kee Oh),구경민(Kyoung Min Koo),이재근(Jae Keun Lee),안영철(Young Chull Ahn) 대한설비공학회 2015 설비공학 논문집 Vol.27 No.2
In this work, we studied the shell and helically coiled tube heat exchangers. Shell and coil heat exchangers with different rate of water flow and plate heat exchanger with same capacity were tested for condensing conditions. We proposed design guide using modified Wilson plot method. We compared fouling characteristics between shell and coil heat exchanger and plate heat exchanger, when they were washed and were not washed. The shell and coil heat exchanger showed 120% of higher saturated fouling resistance value and 4% of better heat transfer ratio than the plate heat exchanger.
고영환(Young Hwan Ko),최득관(Deuk Gwan Choi),오세기(Sai Kee Oh) 대한설비공학회 2018 대한설비공학회 학술발표대회논문집 Vol.2018 No.11
Along with international regulatory action to protect the global environment, the refrigeration and air conditioning industry has been challenged continuously to curb the use of fluoridated greenhouse gases. EU countries are introducing F-gas quota system to strengthen environmental regulations on HFCs, which have a significant impact on global warming. These regulations are affecting heat pump and airconditioners in which R410A refrigerants were used. For this reason, residential and light commercial R32 products are gradually expanding in the European market. This study aimed to compare the primary cooling and heating performance of R32 based on the R410A system and to guide R32 system design by comparing core components. The thermodynamic performance of the R32 is expected to be around 104% and can be developed without major changes in core components when switching to an inverter. Reductions in refrigerant charge are expected to decrease by 15 ~ 25% and CO2 reductions are expected to be 72.5 ~ 75.8%.
데이터 학습 기반 열역학 해석모델을 이용한 히트펌프 건조기 시스템 모델 개발
이강욱(Kang Wook Lee),이진욱(Jin Wook Lee),황윤제(Yoon Jei Hwang),박만수(Mansu Park),오세기(Sai Kee Oh) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6
This study integrates and verifies a numerical model and a data learning model by implementing a digital mockup of a heat pump dryer from a model-based design perspective. The refrigerant cycle of the heat pump dryer was calculated by solving the momentum and energy conservation equations, and the drum part was predicted through the artificial neural network(ANN) learned from the accumulated experimental data. In order to verify the system model that integrates the refrigerant cycle and drum model in the Dymola<SUP>Ⓡ</SUP> environment, the dynamic characteristics data of the dryer for 2 - 8 kg drying load conditions were acquired. As a result of verification of the analysis model, a drying time error of less than 6% was shown for a low drying load of less than 5 kg, but an error of 14% was shown for a load of 8 kg.
데이터 학습 기반 열역학 해석모델을 이용한 히트펌프 건조기 시스템 모델 개발
이강욱(Kang Wook Lee),이진욱(Jin Wook Lee),황윤제(Yoon Jei Hwang),박만수(Mansu Park),오세기(Sai Kee Oh) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6
This study integrates and verifies a numerical model and a data learning model by implementing a digital mockup of a heat pump dryer from a model-based design perspective. The refrigerant cycle of the heat pump dryer was calculated by solving the momentum and energy conservation equations, and the drum part was predicted through the artificial neural network(ANN) learned from the accumulated experimental data. In order to verify the system model that integrates the refrigerant cycle and drum model in the Dymola<SUP>Ⓡ</SUP> environment, the dynamic characteristics data of the dryer for 2 - 8 kg drying load conditions were acquired. As a result of verification of the analysis model, a drying time error of less than 6% was shown for a low drying load of less than 5 kg, but an error of 14% was shown for a load of 8 kg.
루버핀 형상에 따른 공조기용 열교환기의 전열 및 착상성능
김주혁(Ju Hyok Kim),이한춘(Han Choon Lee),이상열(Sang Yeul Lee),김홍성(Hong Sung Kim),오세기(Sai Kee Oh) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.6
In order to develop the heat exchanger for outdoor unit with excellent heating and frosting performance, the heat exchanger with various shape of louver fin was investigated experimentally. The conditions to affect the heat exchanger performance such as outer diameter of tube, tube pitch, fin number were fixed. The same heat exchanging rate, the 25% reduction of air pressure drop, and 71% delay of frosting time were achieved by using the louver fin designed with small louvers placed only near the tube.