초음파 진동이 가진된 밀폐용기에서 상변화 열전달 특성

박설현,정대훈,오율권 조선대학교 에너지.자원신기술연구소 2001 에너지·자원신기술연구소 논문지 Vol.23 No.1

Solid-liquid phase change (i.e. melting or solidification) occurs in a number of situations of practical interest. Some common examples include the melting of edible oil. metallurgical process such as casting and welding, and materials science applications such as crystal growth. Therefore, due to the practical importance of the subject, there have been a large number of experimental and numerical studies of problems involving phase change during the past few decades. This study presents experimental work on phase change heat transfer. Especially, in order to increase heat transfer rate. ultrasonic vibrations were introduced. The melting cavity contained one vertical heating surface which dissipates heat at constant power and was insulated on the sides. Experimental observations show that the effect of ultrasonic vibrations on heat transfer is very important throughout melting process. The results of this study reveal that ultrasonic vibrations accompany the effects like agitation, acoustic streaming, cavitation, and oscillating fluid motion. Such effects are a prime mechanism in the overall melting process when ultrasonic vibrations are applied. They speed up the melting process as much as 2.5 times, compared with the result of natural melting. Also, energy can be saved by applying ultrasonic vibrations to the natural melting.

상변화 물질의 상변이 촉진에 관한 실험적 연구

박설현,오율권,차경옥 한국마린엔지니어링학회 2002 한국마린엔지니어링학회지 Vol.26 No.1

Solid-liquid phase change (i.e. melting or solidification) occurs in a number of situations of practical interest. Some common examples include the melting of edible oil, metallurgical process such as casting and welding, and materials science applications such as crystal growth. Therefore, due to the practical importance of the subject, there have been a large number of experimental and numerical studies of problems involving phase change during the past few decades. Also, this study presented the effective way to enhance phase change heat transfer.

초음파 진동이 상변화 열전달에 미치는 영향에 관한 실험적 연구 ( An Experimental Study of the effect of Ultrasonic Vibration on Phase Change Heat Transfer )

박설현,서동표,차경옥,오율권 대한기계학회 2000 대한기계학회 춘추학술대회 Vol.- No.-

국제우주정거장 내부 화재시 연기거동 및 감지특성에 관한 수치 모델링

박설현,이주희,김연규,황철홍 한국화재소방학회 2012 한국화재소방학회논문지 Vol.26 No.6

The onset of fire on the International Space Station (ISS) is a critical problem that can threaten the life of crew members onboard and thus instantaneous fire detection and extinguishment technology has been considered as one of the most important aspects in the ISS operation. In the present study, a numerical analysis was performed to better understanding of the characteristics of smoke behaviors and detection in a pressurized module of the ISS using the NIST Fire Dynamic Simulator (FDS). Numerical results indicate that the smoke flow patterns under zero-gravity condition are clearly different from those under normal gravity condition. In addition, the results obtained from numerical simulations coupled with the PM internal flows are expected to provide basic and useful information in designing the microgravity fire detection devices and establishing in fire response protocol for astronauts or the crew members. 국제우주정거장에서 화재발생은 승선한 승무원들의 생명과 직접적으로 연관된 사안이므로 선실내부에서 언제든지 발생할 수도 있는 화재의 초기 감지 및 진화는 우주정거장의 운영에 있어서 중요한 기술 중 하나이다. 본 연구에서는 국제우주정거장에서 각종 실험과 연구를 진행하는 가압모듈을 대상으로 환기, 연기거동 및 감지에 관한 수치모델링을 수행하였다. 수치모델링은 NIST에서 개발된 FDS(Fire Dynamic Simulator)를 사용하였으며, 부력이 작용하지 않는 국제우주정거장 내부의 무중력환경에서 발생된 화재의 연기거동패턴은 지상에서의 현상들과 큰 차이가 있음을 확인할 수 있었다. 아울러 가압모듈에서 적용되고 있는 환기조건을 고려하여 수행된 연기거동 및 감지특성에 대한 수치 모델링 결과는 향후 무중력환경에 노출된 수 있는 우주선이나 대형우주구조물의 화재검출장비의 설계를 위한 기초적인 자료를 제공함은물론 승선하게될 우주인이나 승무원들의 훈련자료로도 유용하게 쓰일 수 있을 것으로 기대된다.

배관내에서 난류 마찰 저항감소에 관한 연구

박설현,윤정환,서동표,정대훈,오율권 朝鮮大學校 機械技術硏究所 2000 機械技術硏究 Vol.3 No.1

Polymer drag reduction can offer a attractive way to utilize ready-made facilities in crude-oil transport system without additional large expenditure. Also, drag reduction in two phase flow can be applied to phase change system such as chemical reactor, pool and pump impeller which occurs cavitation. But the research on drag reduction in two phase flow has not been investigated. Therefore, experimental investigations have been carried out to analyze the drag reduction in the single phase and two phase flow. The objectives of the proposed investigation are primarily to identify and develop high performance polymer additives for fluid transportation. And drag reduction will be evaluated in horizontal flow by measuring void fraction, pressure drop, mean liquid velocity and turbulent intensity

음향 흐름에 의한 고-액 상변화 열 전달의 촉진

박설현,오율권 한국에너지학회 2002 에너지공학 Vol.11 No.3

The present paper investigated the effect of ultrasonic vibrations on the melting process of phase-change materials (PCM). Furthermore, the present study considered constant heat-flux boundary condition, whereas many of the previous researches had adopted constant wall-temperature condition. The results of the present study revealed that ultrasonic vibrations accompanied the effects like acoustic streaming, cavitation, and thermally-oscillating flow. Such effects are a prime mechanism in the overall melting process when ultrasonic vibrations are applied. They speed up the melting process as much as 2.5 times, compared with the result of natural melting. Also, energy can be saved by applying ultrasonic vibrations to the natural melting. In addition, temperature and Nusselt numbers over time provided a conclusive evidence of the important role of ultrasonic vibrations on the melting phenomena.

가스가 주입된 용기에서 기공율, 기포빈도와 온도측정에 관한 연구

박설현,오율권,서동표 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.2

The local phase volume fraction, bubble frequency and the phase temperature distributions were measured in vertical air injected water baths. An electroresistivity probe was employed for the determination of the local void fraction and bubble arrival frequency. The phase resolved temperatures were measured using a microthermocouple. The thermocouple signals were digitally filtered, and were carried out to characterize the overall structure of the gas-liquid plume and the heat transfer mechanism between the phases.

마이크로중력환경에서 연료증기 체류시간이 Soot형성에 미치는 영향

박설현(Seul-Hyun Park) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.5

국제우주정거장 화재안전 연구개괄

박설현(Seul-Hyun Park),황철홍(Cheol-Hong Hwang) 한국연소학회 2012 한국연소학회지 Vol.17 No.4

Due to a significant leap in the science and technology, the manned space exploration that has started with suborbital flights is now being expanded into the deep space. The space superpowers such as the U.S. and Russia have been making an effort to further develop the manned space technology. Among such technologies, the fire safety technology in microgravity has recolonized as one of the most critical factors that must be considered for the manned space mission design since the realistic fire broke out onboard the Mir station in 1997. In the present study, the flame characteristics such as flame ignition, shape, spread, and extinction that are critical to understand the fire behavior under microgravity conditions are described and discussed. The absence of buoyancy in microgravity dominates the mass transport driven by diffusiophoretic and thermophorectic fluxes (that are negligible in normal gravity) and influences the overall flame characteristics-flame ignition, shape, spread, and extinction. In addition, the cabin environments of the pressurized module (PM) including the oxygen concentration, ambient pressure, and ventilation flow(which are always coupled with microgravity condition during the ISS operation) are found to be the most important aspects in characterizing the fire behavior in microgravity.

국제우주정거장의 가압모듈에서 연기거동 및 감지에 관한 수치 모델링

박설현(Park, Seul-Hyun),이주희(Lee, Joo-Hee),김연규(Kim, Youn-Kyu),황철홍(Hwang, Cheol-Hong) 한국화재소방학회 2011 한국화재소방학회 학술대회 논문집 Vol.2011 No.추계

최근 국제우주정거장에서 화재안전에 관한 중요성의 인식으로 화재의 감지/소화의 메커니즘을 구체적으로 이해하기 위한 다양한 연구들이 시도되고 있다. 본 연구에서는 국제우주정거장에서 각종 실험과 연구를 진행하는 가압모듈을 대상으로 환기, 연기거동 및 감지에 관한 수치모델링을 수행하였다. 수치모델링은 NIST에서 개발된 FDS (Fire Dynamic Simulator)가 사용되었다. 국제우주정거장 내부는 마이크로중력환경으로 부력이 존재하지 않아 화재 발생 시 화염 및 연기거동은 지상에서의 현상들과 큰 차이를 보이게 된다. 따라서 현재 가압모듈에서 적용되고 있는 환기조건의 변화에 따른 연기거동 및 감지특성에 대한 연구는 향후 국내의 국제 우주정거장 실험 참여를 위한 기초적인 정보를 제공할 것으로 기대된다.