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수평 평활관에서 R134a, R1234ze(E) 및 R1233zd(E)의 막응축 열전달 특성
고지운(Ji-Woon Ko),김선창(Seon-Chang Kim),전동순(Dong-Soon Jeon) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.11
In this study, experimental investigations on the film condensation heat transfer coefficients of R134a, R1233zd(E) and R1234ze(E) were carried out. The goal of present study was to compare the heat transfer coefficients of three different refrigerants mentioned above. And the effect of tube diameter on heat transfer coefficients was also investigated. The saturation temperature and the surface subcooling temperature were 38℃ and 2~16℃ respectively. As a result, it was found that the film condensation heat transfer coefficient of R1234ze(E) and R1233zd(E) were lower than that of R134a about 9.1% and 29.0% respectively. And the larger the tube diameter, the lower the film condensation heat transfer coefficient.
고지운(Ji-Woon Ko),박윤철(Youn-Cheol Park),고광수(Gwang-Soo Ko) 대한설비공학회 2012 대한설비공학회 학술발표대회논문집 Vol.2012 No.6
This study is expected to improve of the picking system efficiency using ground air source heat and to find the system by the geological features in Jeju Island. The performance test conducts that various sensors(temperature, humidity, wind speed) was installed in the operation system. According to the system scale, the horizontal type picking system in tamna middle school and the vertical type picking system in Jeju national university installed. as a result, the horizontal type picking system was leaked. but, the vertical type picking system performance shows that 55%, 21.3℃ for the ground air source heat. a public institution as well as agricultural sector will be able installed the ground air source heat for an air conditioning system.
소각로 배열회수용 열교환기의 최적설계를 위한 열전달 및 압력강하 특성 분석
고지운(Ji-Woon Ko),권오경(Oh Kyung Kwon),배경진(Kyung Jin Bae),전동순(Dong-Soon Jeon) 대한기계학회 2022 大韓機械學會論文集B Vol.46 No.5
본 논문에서는 소각로에 적용하기 위한 배열회수용 열교환기의 설계조건 및 형상인자에 따른 열전달 및 압력강하 특성에 대하여 분석하였다. 배기가스의 입구상태는 실제 운영중인 소각시설의 공정분석 결과를 바탕으로 선정하였다. 배기가스를 통하여 회수 요구되는 목표 열전달량 및 냉각수 출구온도는 각각 550 kW 및 55°C 이상이다. 그리고 관내 및 외측 압력강하량은 열교환기 설계 시 적합한 최소값을 제안하였다. 1차 분석을 통하여 설계조건 및 형상인자가 반응값(열전달량, 냉각수 출구온도, 배기가스 및 냉각수측 압력강하량)에 미치는 영향을 알아보았으며, 선정된 주요인자는 냉각수 유량, 전열관 수직 및 수평방향 간격이다. 2차 분석에서는 열교환기의 최적설계를 수행하였으며, 이때 열전달량 및 냉각수 출구온도는 각각 550.1 kW 및 55.9°C이다. 또한, 관내 및 외측 압력강하량은 각각 7.4 kPa 및 32.7 Pa이다. 따라서 목표한 반응값을 만족하는 최적의 열교환기 형상을 제안하였다. In this paper, heat transfer and pressure drop characteristics of heat exchanger for heat recovery were analyzed according to design parameters. The heat transfer rate and coolant outlet temperature required for recovery through the heat exchanger were 550 kW and 55°C or greater, respectively. For internal and external pressure drop, appropriate minimum values were suggested when designing a heat exchanger. In the 1st analysis, the design parameters affecting the response value (that is, heat transfer rate, temperature of coolant outlet, and pressure drop of gas and coolant) were analyzed; subsequently, the coolant mass flow rate, and the vertical and horizontal spacing of the tubes were selected as main factors. In the 2nd analysis, an optimized design of the heat exchanger was performed. As a result, the heat transfer rate and coolant outlet temperature of the optimally designed heat exchanger were 550.1 kW and 55.9°C, respectively. Additionally, the internal and external pressure drops were 7.4 kPa and 32.7 Pa, respectively. Therefore, the optimal shape of the heat exchanger that satisfied the target response value was presented.
수평 평활관에서 Low GWP 냉매의 막응축 열전달계수에 관한 연구
고지운(Ji-Woon Ko),김선창(Seon-Chang Kim),장수영(Soo-Yeong Jang),전동순(Dong-Soon Jeon) 대한기계학회 2016 대한기계학회 춘추학술대회 Vol.2016 No.12
In this study, we performed experimental investigations on film condensation heat transfer characteris tics of Low GWP refrigerants over a horizontal smooth tube. Low GWP refrigerants used in this study were R1234ze(E) and R1233zd(E). The saturation temperature and the surface subcooling temperature were 38℃ and 2~16℃ respectively. It was found that ranges of the heat transfer coefficients of R134 a, R1234ze(E) and R1233zd(E) were 2.23 ~ 1.68 kW/m²K, 2.01 ~ 1.46 kW/m²K and 1.54 ~ 1.24 kW/m²K respectively. Correlations of film condensation heat transfer coefficients for R1234ze(E) and R123 3zd(E) were also suggested in the present study.