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백재진(J.J.Back),정몽규(M.K.Chung),신칠석(C.S.Shin),백광기(K.K.Back) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.11
Abstract: We have studied on the main causes of pressure drop in the paint hose under the spraying with airless spray pump and suggest calculation method for selecting the optimum<br/> pressure drop during the spraying. Among many factors contributing the pressure drop during the airless spraying procedure of paint, some of the key factors and the correct method for checking. pressure loss between airless pump and spray gun are addressed. We have developed pressure loss calculation method which depending on hose length and diameter, viscosity and flow rate in the painting hose during the spraying. also we have developed calculation equation for the expected spray tip flow rate which depending on pressure and specific gravity and tip size
DAF 공정에서 공기포화장치와 노즐 특성 별 미세기포 발생에 미치는 영향
박상철(S C Park),오호영(H Y Oh),정몽규(M K Chung),송석용(S L Song),안용희(Y H Ahn) 大韓環境工學會 2013 대한환경공학회지 Vol.35 No.12
DAF (Dissolved air flotation) 공정에서 공기포화장치(Saturator)와 미세기포 발생노즐은 미세기포 형성에 중요한 영향을 미치는 장치이다. 미세기포 발생 효율을 증가시키기 위해서는 공기포화장치 용기 안에서 기-액 접촉 효율을 증가시키고, 미세기포 발생노즐까지 이송 배관 내 압력을 일정하게 유지해 주어야 한다. 본 연구에서는 공기포화장치 내 순환수 유입 분사노 즐과 포화수 이송 배관, 미세기포 발생노즐에 의한 미세기포 발생에 미치는 영향을 공기체적법과 기포 크기, 기포의 잔류시간 측정을 통해 비교해 보았다. 순환수 유입 분사노즐을 설치하고, 포화수의 이송 배관 내 압력손실이 발생하지 않는 구조, 미세 기포 발생노즐의 통과유속을 증가시킬 경우 미세기포 발생 성능이 증가하였다. The saturator and injection nozzle are important facilities on the dissolved air flotation process. To increase the formation of micro bubble, it is required to improve the air dissolving performance in the saturator and keep the pressure uniform from the saturator to the nozzle. This study aimed to evaluate the performance of the saturator and the hydraulic effect of the nozzle and the pipe structure. The air volume concentration, bubble size and bubble residual time were measured in the test. The saturator, which had mounted with the spray nozzle, showed a good performance for bubble formation. Also, the characteristics of micro bubble formation were influenced by pressure uniformity and flow velocity through the orifice in the nozzle.
용존공기부상조(DAF-tank)의 형상변화가 분리조(Separation Zone)의 내부 유동 패턴에 미치는 영향에 대한 수치해석적 연구
류광년(Gwang Nyeon Ryu),박상민(Sang Min Park),이호일(Ho Il Lee),정몽규(Mong Kyu Chung) 대한기계학회 2011 大韓機械學會論文集B Vol.35 No.8
용존공기부상조의 파일럿실험장치 설계를 위한 사전 검증 작업으로서 부상조의 유동을 이차원 이상유동으로 가정하여 수치적으로 모사하였다. 형상이 변경된 다양한 부상조와 기준부상조와의 간접적인 성능 비교를 위하여 분리조에서의 하강속도를 비교하였다. 해석 결과 기준부상조의 분리조에서는 잘 설계된 High-rate DAF 의 전형적인 유동 패턴이 관찰되었다. 이러한 유동패턴은 Baffle 각도나 접촉조의 폭과 같은 다른 형상 변수와 상관없이 Baffle 이 충분히 높을 때 잘 유지되었다. 그러나 Baffle 높이 및 각도, 접촉조의 폭 및 다공판의 설치유무는 분리조에서 하강속도의 균일성에 영향을 미쳤다. 기준부상조에서 Baffle 의 높이를 제외한 다른 형상을 변화시키지 않았을 때, 분리조에서의 하강속도가 균일한 것으로 나타났다. 이것은 기준부상조의 형상최적화가 잘 되어있음을 의미한다. We numerically simulated a dissolved air flotation (DAF) tank to predict the performance of the pilot facility. The flow was assumed to be two-dimensional and two-phase. The velocity distributions in the separation zones of differently shaped DAFs were compared to find the effect of the shape on the performance. The results showed that the typical flow pattern that appeared in a well-designed DAF-tank was generated in the separation zone of the base model. This flow pattern could be maintained while the baffle height was sufficiently tall regardless of the other geometric parameters. However, the baffle height and angle, the contact zone width, and the perforated plate affected the uniformity of the downward flow in the separation zone. Except for the baffle height, the base model used in this study showed a better uniformity of downward flow than did other models with different geometric parameters.
백재진(Jae-Jin Baek),윤원준(Won-Jun Yun),이채석(Chae-seok Lee),정몽규(Mong-Ku Chung),신상룡(Sang-ryong Shin),권혁준(hyeog-jun kwon),이병헌(Byung-Hun Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
A significant amount of labor hour is being spent for clean up spent abrasives after blasting. So, for improving the efficiency of abrasive(grit) recovery process which acts as the neck of a battle in preceding coating stage, it was established the theoretical background for pneumatic transport technology in the abrasive recovery system as well as experimentally evaluated the effect of design parameters such as flow pattern, saltation<br/> velocity and pressure drop on the efficiency of the abrasive recovery system. And, by optimizing the operating parameter such as the length and diameter of suction hose, specification of recovery device, recovery mouth and hose connection method, a method which can dramatically increase the efficiency of abrasive recovery system, is derived.
Grit와 Air의 혼합비 최적화를 통한 블라스팅 효율 향상
배한진(Han-Jin Bae),백재진(Jae-Jin Baek),김을현(Eul-Hyun Kim),정몽규(Mong-Ku Chung),신칠석(Chil-Seok Shin),백광기(Kwang-Ki Baek) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.11
Achieving the maximum blasting efficiency with minimum abrasive consumption is a critical concern in surface preparation stage of shipbuilding and offshore industry. Increasing the abrasive flow rate beyond the optimum point results in a major reduction in productivity even though the amount of abrasive used is larger. So, this study is intend to find out the optimum abrasive-to-air mixing ratio which can make a significant improvement in blasting efficiency and remarkably reduce the amount of abrasive used. From the test results, it can be identified that as the abrasive feeding rate is increased linearly, blasting efficiency is increased to a maximum point and then gradually decreased in the form of a bell-shaped.
용존공기부상조(DAF-tank)의 형상변화가 내부유동 패턴에 미치는 영향에 대한 수치해석적 연구
류광년(Gwang Nyeon Ryu),박상민(Sang Min Park),이호일(Ho Il Lee),정몽규(Mong Kyu Chung) 대한기계학회 2010 대한기계학회 춘추학술대회 Vol.2010 No.11
Dissolved air flotation tank was simulated using CFD method to predict its performance. In an excellently designed DAF tank, three typical flow patterns are observed. They are stratified flow just beneath the free surface, vertical flow below the stratified flow, and horizontal plug flow at the bottom respectively. It is well known that a disruption of these flow patterns is disadvantageous for the DAF performance. In this study, these flow patterns were simulated numerically well. However, they were not maintained consistently over time. The effect of geometric shape in the DAF tank on the flow pattern was evaluated numerically as well. The results showed that baffle height, baffle angle, and installation of perforated plate for uniform vertical flow can affect the flow patterns.