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이을종(Lee, Eul-Jong),김정식(Kim, Jeong-Sig),김내현(Kim, Nae-Hyun) 한국산학기술학회 2012 한국산학기술학회논문지 Vol.13 No.12
본 연구에서는 백연방지용 냉각탑의 공기가열기 적용을 목적으로 현재 냉각탑의 충진재로 적용되고 있는 쉐브론형, 웨이브형 그리고 딤플형 전열판 형상에 대한 수치해석을 수행하였다. 해석 결과 동일 소비동력 대비 전열 량은 평판보다 고성능 전열판에서 높게 나타났다. 열전달계수는 웨이브 형상에서 가장 크고 쉐브론 형상, 딤플 형상 순으로 나타났다. 웨이브 형상의 경우 교차하는 절곡형상 사이의 왕성한 혼합유동이 열전달 계수를 증진시킨 것으로 판단된다. 마찰계수는 열전달계수와 유사한 경향을 보였다. 하지만 동일 크기 쉬트에서의 전열량 및 압력손실은 쉐브 론형에서 가장 크게 나타났다. 이는 쉐브론 형상의 전열면적이 다른 형상에 비하여 월등히 크기 때문이다. In this study, numerical analysis was performed on three shapes of heat transfer plates (chevron, wave and dimple type), which are currently used as fillers of cooling towers. Results show that heat transfer rates per consumed power were larger for enhanced plates as compared with that of plain plate. Highest heat transfer coefficient was obtained for wave shape followed by chevron and dimple shape. For wave shape, cross corrugations induced significant mixing of fluids, which enhanced the heat transfer. Friction factor yielded a similar trend with the heat transfer coefficient. However, heat transfer rate and pressure drop per sheet was the largest for chevron shape, due to the largest heat transfer area per sheet.
대구경 원관이 적용된 웨이브 휜-관 열교환기의 공기측 성능
이을종(Eul-Jong Lee),풍익(Yi Feng),심용섭(Yong-Sub Shim),김내현(Nae-Hyun Kim) 대한설비공학회 2012 대한설비공학회 학술발표대회논문집 Vol.2012 No.11
In this study, air-side performance of wave fin-and-tube heat exchangers having large diameter(12.7mm, 15.9mm) tubes was investigated. Eight samples having different tube rows were tested. For both configurations, the effect of tube row on j-factor was negligible. However, f-factor increased as the tube row decreased. The j-factor and f-factor of the tube diameter 12.7mm sample were approximately 32% and 26% higher than those of 15.9 mm sample.
이을종(Eul-Jong Lee),이정표(Jung-Pyo Lee),김내현(Nae-Hyun Kim) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.11
In this study, a moisture transfer model in a membrane was developed. The model requires a moisture diffusion coefficient and an equilibrium adsoption ratio, which were obtained through separate experiments. Enthalpy exchanger was specially made by stacking only membranes (no spacers) to eliminate possible uncertainties induced by spacers. Comparison of the model with experimental data was satisfactory.
이을종(Lee, Eul-Jong),김내현(Kim, Nae-Hyun) 한국산학기술학회 2015 한국산학기술학회논문지 Vol.16 No.5
본 연구에서는 가습소자 개발을 목적으로 절곡형상이 전열판의 성능에 미치는 영향을 수치해석적으로 검토하였다. 수치해석은 절곡각을 변화시키며 (0o/0o에서 60o/60o사이의 등각도와 15o/0o에서 15o/60o사이의 엇각도) 수행되었다. 해석 결과 j와 f 인자 모두 절곡각이 증가할수록 증가하였다. 특히 f 인자는 절곡각이 큰 영역에서 급격히 증가하였다. 엇각도 전열판의 j, f 인자와 두 각을 평균내어 구한 등각도 전열판의 j, f 인자는 거의 같은 값을 나타내었다. 한편 동일 소비동력 대비 열전달 량을 나타내는 j/f ⅓의 경우 15o/15o에서 가장 크게 나타났다. 기존 상관식은 본 수치해석 결과를 과대 또는 과소예측하였다. In this study, the effect of corrugation angle on thermal performance of corrugated plate is numerically investigated with an aim to develop humidifying element. Numerical analysis was conducted for a range of corrugation angle (from 0o/0o to 60o/60o for equal angle and from 15o/0o to 15o/60o for unequal angle). Results revealed that both j and f factor increased as corrugation angle increased. Especially, f factor increased significantly at high corrugation angles. j and f factors of unequal angle plates and those of equal angle (obtained by averaging unequal angles) plates were approximately the same. The largest ?/f1/3, which implies the largest heat transfer rate per consumed power, was obtained at 15o/15o. Existing correlations under- or over-predicted the present numerical results.
이을종(Eul-Jong Lee),송길섭(Kil-Sup Song),오왕규(Wang-Kyu Oh),조진표(Jin-Pyo Cho),김내현(Nae-Hyun Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11
Effect of air humidity on thermal performance of a enthalpy exchanger was experimentally investigated. The apparatus was specially-made to accurately measure the incoming and outgoing dry and wet bulb air temperatures as well as flow rates. Tests were conducted varying outdoor humidity. It is shown that latent heat exchange effectiveness is solely dependent on absolute humidity. The latent heat exchange effectiveness increases with the increase of absolute humidity. The water vapor permeability of the paper membrane was separately measured, and it is found that the permeability also increases with the increase of absolute humidity. Sensible heat exchange effectiveness is independent of both temperature and humidity.
가습소자 주름 각도변화에 따른 수치해석을 통한 성능해석
이을종(Eul-Jong Lee),변호원(Ho-Won Byun),정영빈(Youg-Bin Jeong),김내현(Nae-Hyun KIM) 대한설비공학회 2013 대한설비공학회 학술발표대회논문집 Vol.2013 No.11
In this study, numerical analysis was performed on heat transfer and pressure drop of humidification element. The top and bottom corrugation form angular variation of the element is identical and alternate. Results show that heat transfer rates per consumed power is excellent to identical angle in 15 degree and alternate angle in 15-30 degree. The heat transfer coefficient of zero-angle is 15% lower than that of the alternate angle in 15-30 degree. Existing correlations adequately predicted the heat transfer coefficients.
전열교환 엘리먼트 스페이서의 흡습제 함침에 따른 성능비교
이을종(Eul-Jong Lee),송길섭(Gil-Sup Song),이정표(Jung-Pyo Lee),김내현(Nae-Hyun Kim) 대한설비공학회 2010 대한설비공학회 학술발표대회논문집 Vol.2010 No.6
Performance of an enthalpy exchanger with desiccant impregnated spacers was comparison with that of non-impregnated spacer. An apparatus was specially-made to accurately measure the incoming and outgoing dry and wet bulb air temperatures as well as flow rates. Tests were conducted in constant temperature and humidity chambers according to the standard test procedure (KS B 6879). It is shown that enthalpy exchange effectiveness of the enthalpy exchanger with desiccant impregnated spacers 5% higher than that of non-impregnated spacer.
알루미늄 평행류 열교환기 헤더 내 냉매 분배에 관한 연구
이을종(Eul-Jong Lee),김도영(Do-Young Kim),김내현(Nae-Hyun Kim),김수환(Su-Hwan Kim),변호원(Ho-won Byun) 대한설비공학회 2009 대한설비공학회 학술발표대회논문집 Vol.2009 No.-
The refrigerant R-134a flow distributions are experimentally studied for a round header/ten flat tube test section simulating a brazed aluminum heat exchanger. Three different inlet orientations (parallel, normal, vertical) were investigated. Tests were conducted with downward flow for the mass flux from 70 to 130 ㎏/㎡s and quality from 0.2 to 0.6. In the test section, tubes were flush-mounted with no protrusion into the header. It is shown that normal and vertical inlet yielded approximately similar flow distribution. At high mass fluxes or high qualities, however, slightly better results were obtained for normal inlet configuration. The flow distribution was worst for the parallel inlet configuration. Possible explanation is provided based on flow visualization results.
외기 온ㆍ습도 변화에 따른 종이재질 전열교환 엘리먼트 성능에 관한 연구
김내현(Nae-Hyun Kim),이을종(Eul-Jong Lee),송길섭(Kil-Sup Song),오왕규(Wang-Kyu Oh) 대한기계학회 2010 大韓機械學會論文集B Vol.34 No.7
전열교환 엘리먼트는 열회수형 환기유닛의 핵심부품으로, 외기와 실내공기의 열 및 수분교환이 이루어진다. 본 연구에서는 현재 국내에서 사용되고 있는 전열교환 엘리먼트에 대하여 외기의 온ㆍ습도 변화가 전열교환 엘리먼트의 성능에 미치는 영향을 실험적으로 연구하였다. 전열교환 엘리먼트를 통과하는 공기 유량, 입ㆍ출구의 건ㆍ습구 온도를 정밀하게 측정할 수 있는 실험장치를 특별히 제작하였고, 항온항습실내에서 외기의 상대습도 또는 절대습도를 변화시키며 실험을 수행하였다. 실험결과는 현열전달 유용도과 잠열전달 유용도으로 평가되는데 잠열 전달 유용도는 외기의 상대습도의 증가에 따르 증가하였으나 절대습도의 변화에는 거의 무관하게 나타났다. 한편 현열 교환 유용도는 외기의 온도 및 습도 변화에 무관하게 일정하였다. An enthalpy exchanger in which heat and moisture transfer occur between the indoor and outdoor air operates at various outdoor conditions. In this study, the effect of the outdoor-air temperature and humidity on the performance of an enthalpy exchanger was experimentally investigated. An apparatus was specially-made to accurately measure the incoming and outgoing dry- and wet-bulb air temperatures as well as the flow rates. Tests were conducted in constant-temperature and constant-humidity chambers at different outdoor temperatures and humidities. It is shown that the effectiveness of latent-heat exchange increases as the relative humidity increases; further, this effect exhibited minimal dependence on the absolute humidity. However, the effectiveness of sensible-heat exchange is independent of both temperature and humidity.