A Study on the Greenhouse Water Curtain System: Heat Transfer Characteristics

( Suh Won Myung ),( Han Gill Young ) 한국농공학회 1990 韓國農工學會誌 : 전원과 자원 Vol.32 No.-

Energy balance equations Were developed to describe the heat transfer mechanisms in a double layer plastic greenhouse with a water curtain system. Heat transfer variables were determined by using various temperature data measured in a conventional prototype semicircular cross-section greenhouse over a range of water temperatures and water flow rates. The heat transfer coefficient between flowing water and greenhouse air was independent of water flow rates. But the heat transfer coefficient between water surface and the stagnant air space within the double plastic layer was dependent on water flow rates. Substituting the heat transfer coefficients, determined from the energy balance equations in the heat transfer equations, demonstrated various relationships among ambient air temperature, greenhouse air temperature, water temperature, and water flow rates. The heating benefits were linearly related to not only the inside and outside air temperatures but also to the water temperature. The energy conservation effects of the water curtain system were found even initial water temperatures were considerably lower than the greenhouse setting temperatures. Sensitivity analysis for heat transfer coefficients demonstrated that the heat transfer coefficient between greenhouse air and the stagnant air within the plastic layers was the most significant coefficient in the estimation of heating effects.

Analysis of Solar Energy Storage Using Effectiveness on Single Span Plastic Greenhouse with Water Curtain System

이성현(Lee, S.H.),유영선(Ryou, Y.S.),문종필(Moon, J.P.),윤남규(Yun, N.K.),이수장(Lee, S.J.),김경원(Kim, K.W.) 한국신재생에너지학회 2010 한국신재생에너지학회 학술대회논문집 Vol.2010 No.06

This study was carried out in order to reduce the amount of underground water which is used in the water curtain system for retaining heat. To proceed to the research, two plastic green houses of water curtain system were installed. One was equipped of internal small tunnel for keeping warm air in the interior of the house. Then the internal small tunnel for keeping warm air was fitted with PVC duct of 50cm in diameter filled with subsurface water. Storing surplus solar energy in the water filled in PVC duct was the method used to this house. Another was installed with FCU in the middle of the house, and was fitted a circulation motor in water tank for heat storage which was operated from 10 a.m. to 4 p.m. in order to interchange heat with FCU. The latter was installed with four FCUs which has a capacity of 8000kcal per hour. Consequently about 5 degrees celsius could be maintained in the interior of the internal small tunnel for keeping warm air with the external temperature of more than minus 5 degrees celsius. It appeared that the alteration of an internal temperature of the house was flexible depending on the sunlight during daytime. It happened that to prevent the water from freezing, mixing antifreezing liquid in the flowing water of FCU or changing the operating method of FCU was a suitable measure. Also, in order to use the surplus solar thermal energy on plastic green house of water curtain system efficiently, storing the surplus heat during daytime simultaneously finding a method of using water curtain systematic underground water happened to be important. As a result of this research, when the house's interior temperature is below zero the operation of FCU appeared to be impossible. Therefore when supposed that the amount of water used in the house is 150~200ton for stable operation of FCU, using the system mentioned in the above research happened to be appropriate of reducing the amount of subsurface water from 80% to 100% when maintaining the interior of internal small tunnel's temperature for keeping warm air of 5 degrees celsius at the extreme temperature of minus 5 degrees celsius.

논문 : 생물생산시설 및 환경공학 ; 2중 단동비닐하우스의 태양열 축열이용 효과

이성현 ( S. H. Lee ),유영선 ( Y. S. Ryou ),문종필 ( J. P. Moon ),윤남규 ( N. K. Yun ),권진경 ( J. K. Kwon ),이수장 ( S. J. Lee ),김경원 ( K. W. Kim ) 한국농업기계학회 2011 바이오시스템공학 Vol.36 No.3

This study was carried out in order to reduce the amount of underground water which is used in the double layered single span plastic greenhouse for retaining heat. For this research, two plastic green houses of the double layered single span plastic greenhouse were installed. There was equipped of internal small tunnel for keeping warm air in the interior of the house. Then the internal small tunnel for keeping warm air was fitted with PVC duct of 50 cm in diameter filled with subsurface water. The surplus solar energy in the greenhouse was stored in the water in the PVC duct. Four FCUs (Fan Coil Unit), which has the capacity of 8,000 kcal per hour, were installed in the middle of the house, and a circulation motor in heat storage water tank was operated from 10:30 a.m. to 16:00 p.m. in order to circulate water between the water tank and the FCUs. Consequently about 5 degrees celsius could be maintained in the interior of the internal small tunnel for keeping warm air with the external temperature of lower than minus 5 degrees celsius. It appeared that the alteration of an internal temperature of the house was flexible depending on the sunlight during daytime. To prevent the water freezing, mixing antifreezing liquid in the water or operating FCU continuously was needed. Also, in order to use the surplus solar thermal energy on plastic green house of water curtain system efficiently, storing the surplus heat during daytime simultaneously finding a method of using water curtain systematic underground water happened to be important. As a result of this research, when the house`s interior temperature is below zero the operation of FCU appeared to be impossible. Considering the amount of water used in the house with water-curtain-heating system is 150~ 200 ton per day, using the system mentioned in this research showed that reducing the underground water more than 80% in order to maintain the internal temperature as the level of 5 degree celsius at the extreme temperature of minus 5 degrees celsius.

접이식 유연재질의 태양열 집열 시스템 성능 평가

이승주(Seung Joo Lee),송주영(Joo Young Song),김윤정(Youn Jeong Kim),김성수(Sung Soo Kim),강용태(Yong Tae Kang) 대한설비공학회 2016 대한설비공학회 학술발표대회논문집 Vol.2016 No.6

Evaluation of optimal water flow and temperature in response to outdoor air temperature in plastic greenhouse with recirculated water curtain system

김형권,김윤식,전종길,백이,이재한,Bekhzod Khoshimkhujaev,김용철 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.6

This study evaluated the optimal supply water temperature and flow rate in response to the outdoor air temperature in order to maintaina target indoor air temperature and minimize the amount of energy required to reheat a recirculated water curtain in a plastic greenhouse. This paper proposed a multiple regression model that estimated the indoor air temperature using the outdoor air and the inlet water temperatures,as well as the water flow rate, as independent variables. We also established a multiple regression model that estimated theaverage amount of energy required to reheat the recirculated water curtain. To this end, the study analyzed and quantified a reasonableinlet water temperature and water flow rate in response to the outside air temperature using isothermal and iso-energy curves. The resultsindicated that maintaining a higher water flow rate was preferable to maintaining a higher inlet water temperature for cultivation purposes.

Wind Resistance Performance Evaluation of Cable-Type Curtain Wall System on Reinforced Concrete High-Rise Buildings

Hyun Soo Park,Jong Ho Won,Woong June Chung 한국콘크리트학회 2019 International Journal of Concrete Structures and M Vol.13 No.2

In this research, a cable-type wall system that could replace the conventional aluminum curtain wall system for reinforced concrete high-rise buildings is proposed. The cable-type wall system is a newly developed system, which could be used as an existing exterior skin system, and can effectively support the wind load acting on the exterior of the high-rise buildings by the pre-induced initial tension force to the cable supporting the glass. The main advantages of the cable-type wall system are that the expense of construction could be reduced due to the simplicity of the construction. The experiment of structural analysis and air/water tightness was performed to evaluate its feasibility of industrialization. The structural performance of the cable-type wall system was evaluated through the structural analysis and the full-scale experiment to predict the initial pre-tension force and the design load displacement of the vertical one-way cable-type wall system that can be used for a typical floor of the high-rise building. The initial pretension force and structural behavior of the cable were analyzed by using the structural design program MIDAS-Gen. The maximum deformation value in the structural test was found to satisfy the AAMA condition, which is equal to the size of the facade skin system. The air/water tightness test was conducted to verify the performance. Test results show that the cable-type wall system satisfies the air/water tightness performance standards ASTM E283, E331 and AAMA 501.1-05 which are the most basic standards that the facade system must provide. As a result of this study, it is expected that the proposed cable-type wall system could be used for facade system, not only the structural performance but also air/water tightness performance are secured.

가연성 물질에 따른 워터커튼 시스템의 열 및 연기유동 제어특성에 관한 연구

유우준,남준석,김동준,이정균,유홍선 한국화재소방학회 2012 한국화재소방학회논문지 Vol.26 No.2

In this study fire control characteristics for inflammable materials of water curtain system are experimentally analyzed. Heat release rate for pinewood and gasoline was calculated using Room Corner Tester (RCT) and fire test apparatus for water curtain system is manufactured. Nozzles (180 degree of injection angle, 8.2 mm of orifice diameter) are installed at the nearby ceiling of place at 5 m distance from fire originate and temperature profile as well as transmission are obtained from the fire experiment of pinewood and gasoline in the water curtain system. Based on the results, parameters of engineering importance for fire control characteristics of water curtain system such as generation of high temperature smoke and thermal phenomena of fluid flow by injection nozzle are identified. 본 연구에서는 가연성 물질을 고려한 워터커튼 시스템(Water Curtain System)의 열 및 연기유동 제어 특성을 실험적으로 분석하였다. 이를 위해서 Room Corner Tester(RCT)를 사용하여 연료의 종류가 소나무(PineWood)와 가솔린(Gasoline)인 경우 각각의 발열량(Heat Release Rate)을 구하였으며, 워터커튼용 화재실험 장치를 제작하여 화원근방에서 5m 떨어진 지점의 천장 부근에 분사각도 180o, 오리피스 직경8.2 mm의 노즐(Nozzle)을 설치한 후 목재와 가솔린 각각에 대해서 화재실험을 실시하여 워터커튼 전후의온도분포와 가시도를 측정하였다. 그 결과 워터커튼 시스템의 열 및 연기유동 제어는 가연성 물질의 연소특성에 따른 고온의 연기발생량과 분사 노즐에 의한 유동현상이 중요한 상관관계를 갖고 있음을 확인하였다.

산중에 위치한 공공보존기록관의 산림화재 방호를 위한 드렌처노즐 수막방호시스템의 실험연구

이영재,박형주,Lee. Young-Jae,Park. Hyung-Joo 한국방재학회 2013 한국방재학회논문집 Vol.13 No.1

우리나라 국보급 공공보존기록관의 대부분이 산중에 위치하고 있어 인근의 산불화재 시 만에 하나 착화가 일어나면 보존가치가 큰 기록물의 소실이 우려되는 실정이다. 따라서 인근의 산림화염과 비화불티로부터 국가보존기록 시설을 방호할 수 있는 차단시설의 설치가 필수적이다. 인근 산불의 진화에는 한계를 가지고 있어 별도의 산불화염 수막에 의한 건물외곽의 드렌처 분무 차단시스템이 강구되어야 할 것으로 조사되었다. 따라서 본 연구에서는 산불화염이 주는 고온의 복사열과 비화불티로부터 기록관 창문 등의 개구부 또는 가연성 외장재로의 확산을 차단하는 데 효과적인 드렌처 설비를 개발하여 현장에 시범적으로 적용하여 그 성능을 평가하였다. 성남에 위치한 나라기록관을 대상으로 다양한 드렌처 노즐과 분무유량을 변경하여 시범적으로 설치, 실험하여 분석하였다. 특히 기록관의 높은 건물고(약 30 m)를 고려하여 효과적으로 시설 전체를 방호하기 위해서는 분사 길이가 짧은 소구경 워터스프레이 드렌처 노즐보다는 대구경 워터 스플래쉬식 드렌처 노즐이 효과적인 것으로 분석되었다. 결론적으로 층고에 비례하여 장(長)수막을 형성하기 위해서는 워터 스플래쉬 방식의 드렌처를 사용한 수막시스템이 저비용 및 성능 면에서 가장 탁월하였음을 실험적으로 규명하였다. Most of Korea National Archives among the mountain exposed to forest fire environments, therefore, people has worried about their burn-out from neighbouring forest fires. It is necessarily protected from both flame radiant and flying fire-flakes. It has investigated that special water-screen protection system become one of the alternatives for preventing them from neighbouring forest fires due to limitation on extinguishing ability of fire regional fire departments. This study has focused on a development and assessment of various water-screen protection system formed by drencher nozzles for prevention the Nara national archive facility from igniting flame radiant and fire-flakes. Because a water-screen protection system using water-splash nozzles installed on surrounding roof-top line only has proved very effective, we could accept the effect of binding capacity of splash water droplets in terms of screening films`s quality.

3차원 물방울 조각 생성장치의 구현을 위한 물방울 생성기법

임용춘,박연용,정문열 (사)한국컴퓨터그래픽스학회 2019 컴퓨터그래픽스학회논문지 Vol.25 No.3

본 논문은 3차원 물방울 조형 생성장치로 구현된 3차원 물방울 조형을 생성할 때 위성 물방울이 생성되지 않고 형상 왜곡이 일어나지 않으면서 조형의 해상도를 최대한으로 높일 수 있는 기법을 제안한다. 3차원 물방울 생성장치는 보통 표현하고자 3차원 조형을 등 간격으로 배치된 슬라이스들의 집합으로 이산화하여 표현하고 각 슬라이스를 순서대로 읽어 각 슬라이스를 실현하는 물방울을 솔레노이드 밸브를 개폐하여 생성한다. 각 슬라이스의 해상도는 솔레노이드 노즐 매트릭스의 해상도와 같다. 본 논문에서는 위성 물방울이 생성되지 않으면서 형상의 왜곡도 생기지 않는 새로운 기법 두 가지를 제시하고자 한다. 첫째 방법은 등간격 기법이라고 하는데, 등간격으로 배치된 각 슬라이스를 생성하는 시점을 조절하여 중력에 의해 시간이 지날수록 물방울의 속도가 빨라지더라도 조형 전체가 다 형성되는 순간에 물방울 슬라이스들이 등 간격을 유지하게 하여 원래의 형상이 왜곡되는 것을 방지한다. 두 번째 방법은 최소시간 간격 기법이라고 하는데, 3차원 조형을 슬라이스로 이산화시킬 때, 슬라이스를 등 간격으로 배치하는 것이 아니라 가능한 한 촘촘하게 배치한다. 중력을 고려하여 조형 위쪽으로 갈수록 슬라이스를 더 촘촘하게 배치하고, 아래로 내려올수록 슬라이스 간의 간격이 늘어나게 배치한다. 이때 주어진 노즐의 성능 한도 내에서 최대한 촘촘하게 불균등 간격 슬라이스를 배치하고 조형이 완성되는 시점에 이 간격이 실현되게끔 노즐 개폐를 제어한다. 이 방법을 구현하기 위해 주어진 물방울 생성장치의 솔레노이드 밸브가 위성 물방울 생성 없이 인접한 두 물방울을 연달아 생성하는데 필요한 최소 시간 간격 (노즐 오픈 명령후 노즐이 완전히 오픈되는데 걸리는 시간과 완전 오픈상태를 유지하는 시간, 그리고 노즐 클로즈 명령후, 노즐이 완전히 클로즈 되는데 걸리는 시간의 합) 을 실험으로 구했다. 두 번째 방법은 첫 번째 방법에 비해 조형의 해상도가 상당히 증가하는 장점이 있다. This paper presents two new techniques for solving the two problems of the water curtain: 'shape distortion' caused by gravity and 'resolution degradation' caused by fine satellite droplets around the shape. In the first method, when the user converts a three-dimensional model to a vertical sequence of slices, the slices are evenly spaced. The method is to adjust the time points at which the equi-distance slices are created by the nozzle array. In this method, even if the velocity of a water drop increases with time by gravity, the water drop slices maintain the equal interval at the moment of forming the whole shape, thereby preventing distortion. The second method is called the minimum time interval technique. The minimum time interval is the time between the open command of a nozzle and the next open command of the nozzle, so that consecutive water drops are clearly created without satellite drops. When the user converts a three-dimensional model to a sequence of slices, the slices are defined as close as possible, not evenly spaced, considering the minimum time interval of consecutive drops. The slices are arranged in short intervals in the top area of the shape, and the slices are arranged in long intervals in the bottom area of the shape. The minimum time interval is pre-determined by an experiment, and consists of the time from the open command of the nozzle to the time at which the nozzle is fully open, and the time in which the fully open state is maintained, and the time from the close command to the time at which the nozzle is fully closed. The second method produces water drop sculptures with higher resolution than does the first method.

가스발생기 후연소설비의 연소시험 결과

김채형,이광진,유병일,김성룡,황창환,한영민 한국항공우주학회 2015 한국항공우주학회 학술발표회 논문집 Vol.2015 No.11

75톤급 액체로켓엔진의 가스발생기 후연소 설비는 가스발생기에서 배출되는 연료 과농 배기가스를 연소시키는데 목적이 있다. 단독성능 시험에서 공급시스템은 감압 없이 일정한 압력으로 가스발생기 점화기 토치와 후연소 토치쪽으로 메탄과 산소를 공급했으며, 가스 토치 압력은 설계값을 만족하였다. 가스발생기 점화용 가스토치와의 연계시험에서 가스발생기 점화 성능과 연료과농 배기가스의 후연소 성능에 관한 시험을 성공적으로 수행하였다. 주변 화재 발생을 막기 위해 설치한 물장막은 소방설비로서의 작동성능도 확인되었다. After-burner facility for gas generator of 75 tonf liquid rocket engine was designed to burn the fuel-rich exhaust gas from the gas generator. In the case of the autonomous test, the supply system provided steadily methane and oxygen gases to the after-burner system without pressure drop, and the combustion pressure of the gas torch approached the design point with good performance. In the case of the coupled test with the gas toch ignitor for the gas generator, the gas generator ignition and the fuel-rich exhaust gas combustion were well carried out, leading to the verification of the test facility. A water-curtain was installed to prohibit the fire accident around the after-burner facility, and its performance was verified.