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나인(Md. J. Nine),이경환(G. H. Lee),정효민(H. M. Jeong),정한식(H. S. Chung) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
The article represents an experimental investigation on pressure drop and friction loss behaviors of free airflow through a rectangular duct fitted with semicircular ribs of uniform height on one principle wall. The aspect ratio of the rectangular duct is AR= 5, duct height was of H= 30 ㎜ and uniform rib heights (e = 3.5 ㎜m) were used for three different rib pitches of 30 mm, 35 ㎜ and 42 ㎜. For this cases, the rib height to hydraulic diameter ratio were e/D = 0.07 and rib height to channel height ratio were e/H = 0.11. The experimental results show some significant effects of static pressure near the wall and at various configurations and different numbers of rib arrangements within test section. Each result is compared with another among different configurations of rib arrangement over the 90 ㎝ X 15 ㎝ copper plate test section. The Reynolds number in the inlet of calculation domain was in a range of 10000 to 30000. Digital micro manometer and pressure transducer were used for taking static pressure of this experiment. Darcy friction factor was used and isothermal pressure drop had been considered in data evaluation. These experiment will be the preliminary investigation for turbulence analysis as heat transfer enhancement using periodic semicircular ribs.
Numerical and Experimental Study on the Steam Ejector
S. Wibowo(위보워),M. Sq. Rahman(라흐만),J. S. Woo(우주식),H. M. Jeong(정효민),H. S. Chung(정한식) 한국마린엔지니어링학회 2009 한국마린엔지니어링학회 학술대회 논문집 Vol.2009 No.-
Ejectors are simple pieces of equipment. They are employed in the industry such as in refrigeration and air conditioning, desalination, petrochemical and chemical industry. The purpose of this paper is to reveal the complication of the flow and the mixing process in a steam ejector. Air was used as primary and secondary fluids here. In this experiment, the influence of nozzle exit positions was investigated. The result shows the static pressure distribution along the ejector wall is influenced by nozzle exit position. In this study CFD simulation were also undertaken. Standard k-epsilon, RNG k-epsilon, and Realizable k-epsilon were tested in CFD. The CFD results were validated with available experimental data. In this case the result shows that realizable k-epsilon model closer with experimental result than another models.
Study of Steam Ejector in Experimental and Numerical
S. Wibowo(위보워),M. Sq. Rahman(라흐만),G. H. Lee(이경환),H. M. Jeong(정효민),H. S. Chung(정한식) 한국동력기계공학회 2009 한국동력기계공학회 학술대회 논문집 Vol.2009 No.6
Steam jet ejectors are essential part in many industrial applications such as refrigeration and air conditioning, desalination, chemical industries, and so on. In this study, experiment and numerical of jet ejector model were investigated to reveal the complication of the flow and the mixing process in a steam ejector. Air was used as primary and secondary fluids in experiment. In the experiment, the influence of nozzle exit positions was investigated. The result shows the static pressure distribution along the ejector wall is influenced by nozzle exit position. We also carried out CFD simulation in this study. Realizable k-epsilon turbulence model was tested in CFD. The CFD results were validated with available experimental data.
Experimental study on Vacuum evaporation by ejector of fresh water generator system
S. Wibowo(위보워),ZhenHua Zin(김진화),J.S. Woo(우주식),H. M. Jeong(정효민),H. S. Chung(정한식) 한국동력기계공학회 2009 한국동력기계공학회 학술대회 논문집 Vol.2009 No.11
담수와 시스템은 염수를 음용수로 만들기 위해 해수에 열을 가하는 형태로 설계된다. 본 논문에서는 진공 튜브 증발을 하는 한 가지 형태의 청수제조장치의 진공튜브내의 특성을 알아보았다. 담수에 필요한 열에너지는 증류법을 이용하여 비등점을 내릴 수 있다. 이 실험에서는 증발기로 보내는 물의 온도는 60~90로 제어하여 실험하였다. 이는 버려지는 저압의 스팀과 같은 에너지를 이용하여 담수화 시스템을 구성할 수 있다.
이상철(S. C. Lee),김영근(Y. G. Kim),이효덕(H. D. Lee),김세현(S. H. Kim),정한식(H. S. Chung),정효민(H. M. Jeong) 한국동력기계공학회 2004 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The latent heat of evaporation of LNG is very effective and this generated in vaporization process of LNG. This energy is evaluated with value of 199.12 ㎉/㎏ (1.03 atm, -16 1 ~ 0℃). The purpose of this study represents the heat exchange characteristics of super low temperature liquefied natural gas. As the experimental liquefied gas, LN₂ was used in experiment and the main experimental parameter is chosen the flow rate and inflow air velocity. The experiment was performed for twenty minutes with several times. Temperatures distributions were obtained by T-type thermocouples. The heat exchange effects were dropped by a moisture freezing at heat exchange surface and various inlet air velocity were considered for temperature environment in chamber.
하류 유동제어에 의한 에젝터의 효율상승 방법에 관한 연구
김세현(S. H. Kim),이상철(S. C. Lee),신유식(Y. S. Shin),최석천(S. C. Choi),정효민(H. M. Jeong),정한식(H. S. Chung) 한국동력기계공학회 2004 한국동력기계공학회 학술대회 논문집 Vol.- No.-
The ejector system is used for making a low pressure in industrial field. The ejector is consists of nozzle, mixing section and diffuser. The diffuser is influenced in low pressure of ejector system. The diffuser is an important fluid-mechanical equipment to convert kinetic energy into pressure energy. Many of the experimental and theoretical researches have been done in a diffuser but the understanding of energy transfer and detailed mechanism of energy dissipation is unclear. In this study, computations were performed using a numerical method with SIMPLE algorithm for conical diffuser with various diffuser angles and Reynolds number. Also, we investigated the pressure recovery coefficient in conical diffuser by inserting strut. In this paper, we showed that the strut can cause a rising pressure recovery.