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증기 구동식 진공 시스템을 이용한 해수 냉각 특성에 관한 실험적 연구
최민식(Min-Sik Choi),金鎭花(Zhen-Hua Jin),신유식(You-Sik Shin),정효민(Hyo-Min Jeong),정한식(Han-Shik Chung),배태열(Tae-Yeol Bae) 대한기계학회 2006 대한기계학회 춘추학술대회 Vol.2006 No.11
A steam ejector is a device which is used to transport vapor or liquid at low pressure to a higher pressure or to make vacuum as its simplicity and reliability. It is widely used in refrigeration system, power system and food industry etc. This study showed the water cooling system by using a steam ejector to drop water temperature by about 5℃ from 25℃ or higher. In this study, to replace the present water cooling system, we focused on a water cooling system operated by the latent heat of evaporation, thus this system needs a vacuum pressure to evaporate the water in enclosed tank. The water cooling effects are depended on the vacuum pressure in the enclosed tank, and the cooling water is generated by the latent heat of evaporation. As the experimental results, the absolute vacuum pressure was obtained about 8~12㎜Hg by using a steam ejector. The necessary time to reach this vacuum pressure was about 5minutes and the temperature difference of the water were obtained about 5℃.
신유식(You-Sik Shin),배강열(Kang-Youl Bae),배철환(Chul-Whan Bea),이윤환(Youn-Hwan Lee),정효민(Hyo-Min Jeong),정한식(Han-Shik Chung) 대한기계학회 2002 대한기계학회 춘추학술대회 Vol.2002 No.5
This paper is the study on the performance of cooling tower system by using the low vacuum. Currently, the cooling system is using at many parts of the industry. But, the present system have many problems for the cooling process. Thus, This research aimed for replacing the present cooling<br/> tower system. This new cooling tower system have a low vacuum, and have a ejector system to maintain a low pressure. As a main experimental parameter, we introduced a flowrate at the inlet ejector system.
응축기 설계조건에서 R12, R134A, R407C의 압력강하 해석
우주식(Ju-Sik Woo),윤재근,정한식(Han-shik Chung),정효민(Hyo-Min Jeong) 한국마린엔지니어링학회 2009 한국마린엔지니어링학회 학술대회 논문집 Vol.2009 No.-
In designing of condensers, the prediction of pressure drop is very important to predict the heat transfer coefficient. Modeling of two phase flow, inside a horizontal tube using CFD analysis is difficult with available two phase model in Fluent because of its changing flow patterns continuously. In this paper presents the CFD analysis of two phase flow of refrigerants inside a horizontal tube of 1.2m length three different inner model diameters of 0.0125m respectively, is carried out using Homogeneous model under adiabatic condition. The considered refrigerants are R12 and R134a. The analysis is conducted at different temperatures and flow rates to evaluate the local frictional pressure drop. Using Homogeneous model, average properties are obtained for each refrigerants. Obtained pressure drop data is compared with separated flow models available in literature.
신유식(You Sik Shin),이윤환(Youn Hwan Lee),이상철(Sang Chul Lee),김세현(Se Hyun Kim),정효민(Hyo Min Jeong),정한식(Han Shik Chung) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
The cooling tower is a device for making a cooling water in the air conditioning system of building, and there are many kinds of cooling tower system for air conditioner. In this paper, we introduced the water cooling system with an enclosed tank and water ejecting system for evaporating the water in tank. The city water was used for a working fluid, and the cooling water is generated by evaporating latent heat in the tank with a 25~50mmHg. The time to reaching this vacuum pressure was about 20~30minutes, and cooling water was obtained the value of temperature difference ΔT=7℃.
윈드터빈 자연환기 장치의 외기풍속 및 온도차에 따른 환기특성에 관한 실험연구
한동훈(Dong-Hun Han),김영식(Yeong-Sik Kim),정한식(Hanshik Chung),정효민(Hyomin Jeong),최순호(Soon-Ho Choi) 대한설비공학회 2017 설비공학 논문집 Vol.29 No.4
With the improvement of living standards, the ventilation for the mitigation of indoor or outdoor air-pollution problems has recently attracted a lot of attention. Consequently, the ventilation for the supply of outdoor fresh air into a room is treated as an important building-design factor. The ventilation is generally divided into the forced and natural types; here, the former can control the ventilation rate by using mechanical devices, but it has the disadvantages of the equipment costs, maintenance costs, and noise generation, while the latter is applied to most workshops due to the absence of noise and the low installation and maintenance costs. In this experimental study, the ventilation performance of a typical rotating-type natural ventilator, which is called a “wind turbine,” was investigated with the outdoor-wind velocity and the indoor/outdoor-temperature difference. From the experiment results, it was confirmed that the temperature difference of 10℃ corresponds to the ventilation driving force with an outdoor-wind velocity of 1.0 m/s. Additionally, the intake-opening area of a building also exerts a great effect on the ventilation rates.
박진관(Chen Kwan Park),신용한(Yong Han Shin),우주식(Ju Sik Woo),정효민(Hyo Min Jeong),정한식(Han Shik Chung) 한국지열·수열에너지학회 2011 한국지열에너지학회논문집 Vol.7 No.1
Renewable energy is growing based on low-carbon green energy government policies. According to this policy, geothermal energy is highly efficient and environmental friendly energy which is being recently expanded. However, construction companies are generated disorderly but their ability has not been verified due to the poor geothermal facility which was reported in the media. In the this paper introduce on Busan region's largest geothermal facility, it was confirmed that thermal efficiency of the underground is close to heat exchanger performance. Therefore the study improving the efficiency of underground heat exchange found progressed. The results showed voids between borehole and ground heat exchanger should not be raised. And then geothermal facilities were installed very successfully through the principle grouting operation. As compared to the energy consumption on the basis of operating results energy usage was less than any other heat sources.
육상 수조식 양식장의 유입 유량 변화에 따른 온도와 속도의 특성
김세현(Se Hyun Kim),신유식(You Sik Shin),전유신(You Sin Jun),서종수(Jong Soo Seo),정효민(Hyo-Min Jeong),정한식(Han-Shik Chung) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
This study was performed to analyze the velocity and temperature distributions of the land aquaculture tank for fish breeding. In this study, we analyzed the velocity and temperature distributions in aquatium tank, and the finite volume method and standard k-ε turbulence model with the SIMPLE computational algorithm are used to study the water flow in the aquarium. The main calculation parameters of the aquarium tank are the inlet flow rate with from 0.5 to 2.0L/M.
진동열교환기에서 다양한 충진율에 따른 압력및 진동특성에 관한 연구
리야드(Md.Riyad Tanshen),김영식(Young-Sik Kim),이대철(Dae-chul Lee),정한식(Han-Shik Chung),정효민(Hyo-Min Jeong) 대한설비공학회 2011 대한설비공학회 학술발표대회논문집 Vol.2011 No.7
The article focuses on pressure characteristics inside single loop oscillating heat pipe (OHP) that is of 4.5 ㎜ inner diameter copper tube with the length of 440 ㎜. The system consists of evaporator, condenser and adiabatic section at middle of heat pipe. Distilled water is used as working fluid inside the OHP with different filling ratios of 40%, 60%, 80% of total volume. Experimental results shows that thermal characteristics are significantly inter-related with pressure fluctuations as well as pressure frequency. And the pressure frequency also depends upon the evaporator temperature which has been maintained from 60oC to 96oC. The Investigation shows 60% filling ratio gives the highest magnitude of inside pressure and highest pressure frequency at any of setting evaporator temperature. Piezoresistive absolute pressure sensor (Model-Kistler 4045A5) has been used to take data.