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COVID-19 실내 확산 방지를 위한 급배기 특성 CFD 분석
설성훈,손창효,김영복,차승윤,박상찬,윤정인 한국동력기계공학회 2022 동력시스템공학회지 Vol.26 No.1
The outbreak of COVID-19 still seriously affects our daily lives despite the actions with governmental level to prevent the situation from getting worse. Among various infection routes of COVID-19, airborne spread needs to be carefully handled in the perspective of HVAC. In particular, cluster infection in multi-use facilities which unspecified number of people use is now the big issue. One of the most simple solution is to dilute virus pollution through the proper ventilation. Therefore, this study analyzes the effect of the location of diffusers and the ventilation rate on the indoor air distribution in the large space through a numerical method. The results show that the zigzag arrangement was the most suitable for ventilation because of its high average and minimum air velocity.
설성훈(Seol Sung-Hoon),윤정인(Yoon Jung-In),이준혁(Lee Joon-Hyuk),차승윤(Cha Seung-Yun),하수정(Ha Su-Jeong) 한국태양에너지학회 2021 한국태양에너지학회 논문집 Vol.41 No.4
In this study, the condensation heat transfer characteristics of the R-1234yf refrigerant were analyzed according to the variation in tube diameter, which were then considered as condenser design data. The inner diameter of the experimental tube was varied from 3.7 ㎜ to 5.3 ㎜. Subsequently, the heat transfer coefficient of R-1234yf was analyzed according to the changes in vapor quality, mass flux, saturation temperature, and pipe diameter. Slug flow was observed at a low mass flux, and annular flow was observed at a high mass flux. Furthermore, it was observed that the heat transfer coefficient’s value increased with increase in the vapor quality and mass flux, whereas it decreased with increase in the tube diameter and saturation temperature. By comparing the heat transfer coefficients of the refrigerants R-134a and R-1234yf, it was found that the heat transfer coefficient of R-134a is higher. Furthermore, four correlations were conducted, and it was found that the correlation of Dobson and Chato and the correlation of Bashar can predict the experimental condensation heat transfer coefficient within an error range of ±10%.
귀에 발생한 가성낭종의 수술 후 실리콘 자석 압박 치료 사례 1예
설성훈(Seong Hoon Seol),정찬민(Chan Min Chung),박명철(Myong Chul Park) 대한두경부종양학회 2022 대한두경부 종양학회지 Vol.38 No.1
Endochondral pseudocyst of the ear is a rare, benign, non-inflammatory cystic disease. It is known that there are a variety of treatment methods for pseudocyst, which is mainly common in the scaphoid or triangular fossa of the ear. Pseudocyst formation is prevalent in the residual cavity of the ear. So, to prevent a recurrence, a surgical approach is also required, but management through compression is necessary after surgery. Applying a cube magnet to the lesion to press provides patient convenience and facilitates continuous management.
BTMS용 열교환기의 형상에 따른 성능 비교 part 1: Offset Fin과 Dimple 타입의 비교
주영현,설성훈 한국동력기계공학회 2023 동력시스템공학회지 Vol.27 No.6
As a heat exchanger for battery thermal management system (BTMS), the offset fin is widely used to reduce the size of heat exchanger due to its substantially enhanced heat transfer. However, the large level of pressure drop occurs that needs to be considered carefully. On the other hand, the dimple type heat exchangers can be a good option to decrease pressure drop due to its relatively simple turbulator structure. When it comes to evaluate heat exchangers, it is essential to join thermal performance together with hydralic performance by estimating Colburn j factor and Fanning f factor. This research compared two types of heat exchangers, namely an offset fin type and a dimple type, by various parameters including dimensionless numbers. As a result, presence of additionally placed turbulators of the dimple type heat exchanger seemed not practical because of still low Colburn j factor and steeper decrease of flow area goodness factor according to Reynolds number. In addition, application of half-circuit structure needs to be reconsidered due to the same reason.
냉매 오염에 따른 냉동장치의 성능저하와 냉매의 재생을 통한 경제적 및 환경적 효과 분석
이준호,설성훈 한국동력기계공학회 2024 동력시스템공학회지 Vol.28 No.1
본 연구는 첫째로 냉동장치의 장기 사용에 따라 발생할 수 있는 냉매의 오염에 의한 장치의 성능변화를 실험적으로 분석하는 것과, 둘째로 오염된 냉매를 재생하여 사용함으로써 얻을 수 있는 경제적 그리고 환경적 효과에 대해 다루고자 한다. 냉매의 오염 요인으로는 불응축가스와 압축기 오일의 과다 주입으로 정하였다. 냉매는 GWP 수치가 높아 냉매 재생의 수요가 예상되는 HFC계열의 R-134a를 적용하였다. 불응축가스는 압축기 일량을 증가시키며 COP 감소를 야기하였고, 냉동기 오일의 과다 주입은 증발열량의 감소를 초래하였지만, 냉각 및 윤활 성능의 개선도 이루어져 압축기 토출가스 온도는 감소하는 경향을 보였다. 재생된 냉매가 기준을 제대로 충족하면 신품 냉매와 비교해 성능에 차이가 없음을 실험적으로 확인하였다. 냉매의 재생에 수반되는 비용의 회수 기간은 오염정도에 따라 다르나 대체로 수개월 내로 분석되며, 온실가스 배출량은 신규냉매의 소비억제로 인해 1,256 kgCO2eq/RT, 운전효율 저하 억제로 인해 연간 25.44 kgCO2eq/RT의 효과를 보였다. This study aims, firstly, to experimentally analyze the performance variations of a refrigeration device based on contamination factors. Secondly, it also includes investigation of the economic and environmental effects of use of recycling contaminated refrigerants. Contamination factors for the refrigerant were determined as non-condensable gases and excessive injection of compressor oil. The refrigerant selected for this study is R-134a, belonging to the HFC series with anticipated demand for refrigerant recycling due to its high GWP value. Non-condensable gases increase compressor workload and lead to a decrease in COP. Excessive refrigeration oil resulted in a reduction in evaporation capacity, but improvements in cooling and lubrication performance led to a decrease in the discharge gas temperature of the compressor. It was experimentally confirmed that recycled refrigerant, if it meets the specified standards (KS I 3004), exhibits no performance differences compared to fresh refrigerant. The payback period for the cost associated with refrigerant regeneration varies depending on the degree of contamination but is generally analyzed to occur within several months. The reduction in greenhouse gas emissions is observed at 1,256 kgCO2eq/RT due to the restraint of new refrigerant consumption and an annual effect of 25.44 kgCO2eq/RT due to the suppression of operational efficiency degradation.