• 융합정보논문지
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• 제10권2호
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• pp.82-88
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• 2020

본 연구는 화공용 열교환기에서 법랑코팅 적용을 위한 고온의 소성 공정조건 최적화에 대한 기초자료를 얻고자 하는데 그 목적이 있다. Shell & Tube 형태인 열교환기에 법랑코팅 적용을 위해 소성온도를 순차적으로 높이는 방안에 대해 검토하였다. 소성로 내부에서 열교환기의 온도분포에 대해 CFD 상용 프로그램으로 수치계산하여 구한 온도를 하중조건으로 열응력 해석을 수행하는 연성 해석(FSI) 방식을 이용하여 열교환기의 구조 안전성에 미치는 영향을 확인하였다. 수치해석 및 실험결과 상온의 열교환기를 바로 860℃도의 소성로에 넣으면 열교환기의 국부적 온도차로 인한 구조 안전성에 문제가 발생하므로 온도차를 줄이기 위한 예열 과정이 필요하다. 소성공정 단계가 적은 Case2와 같이 1단계 예열온도 445℃, 2단계 소성온도 860℃가 가장 적합한 것으로 판단된다.

• 대한기계학회논문집
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• 제14권1호
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• pp.251-258
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• 1990

본 연구에서는 제 1보에서 다루었던 프로세스 해석의 결과들을 토대로 하여 열교환기의 최적 설계를 행하는데 주력하였다. 먼저, 열교환기의 최적 설계를 행하 는데 주력하였다. 먼저, 열교환기의 열설계에 필요한 CO$_{2}$와 Natrium의 물성치 및 열전달에 관한 기존의 실험식들을 여러문헌으로부터 연구 검토한 후 프로그램에 편 리하게 이용할 수 있도록 전산화 하였으며, 열교환기의 설계시 필요한 전체 경비의 최 소화를 기하는 방향으로 최적화된 설계인자들을 결정하도록 시도하였고 또한 최적화된 프로그램을 개발함으로써 인력, 외화 및 에너지 절감의 효과를 얻고자 하였다.

• 한국초전도ㆍ저온공학회논문지
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• 제24권3호
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• pp.62-67
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• 2022

Liquid hydrogen (LH₂) has a higher density than gaseous hydrogen, so it has high transport efficiency and can be stored at relatively low pressure. In order to use efficient bulk hydrogen in the industry, research for the LH₂ supply system is needed. In the high-pressure hydrogen station based on LH₂ currently being developed in Korea, a heat exchanger is used to heat up supercritical hydrogen at 700 bar and 60 K, which is pressurized by a cryogenic high-pressure pump, to gas hydrogen at 700 bar and 300 K. Accordingly, the heat exchanger used in the hydrogen station should consider the design of high-pressure tubes, miniaturization, and freezing prevention. A helical heat exchanger generates secondary flow due to the curvature characteristics of a curved tube and can be miniaturized compared to a straight one on the same heat transfer length. This paper evaluates the heat transfer performance through parametric study on the distance between coils, guide effect, and anti-icing design of helical heat exchanger. The helical heat exchanger has better heat transfer performance than the straight tube exchanger due to the influence of the secondary flow. When the distance between the coils is uniform, the heat transfer is enhanced. The guide between coils increases the heat transfer performance by increasing the heat transfer length of the shell side fluid. The freezing is observed around the inlet of distribution tube wall, and to solve this problem, an anti-icing structure and a modified operating condition are suggested.

• 설비공학논문집
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• 제18권11호
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• pp.941-946
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• 2006

Nowadays heat exchangers that have been applied for freon refrigerating systems, a shell and tube type condenser, but because of their large size, large space for installation and more amount of refrigerants are needed. Therefore, in this study, we will find the most suitable operating condition through the comparison of performance between the shell & tube type and shell & disk type heat exchanger with R22. The experiments are carried out for the condensing pressure of refrigeration system from 1,500 kPa to 1,600 kPa and for the degree of superheat from 0 to $10^{\circ}C$ at each condensing pressure. As a result of experiment, if the shell & disk type heat exchanger is applied for R22 refrigerating systems, minimized input of refrigerants and space required for installation will be secured, which will have a great contribute to financial improvement for industry.

• 농업생명과학연구
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• 제44권4호
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• pp.29-43
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• 2010

The numerical analysis by using CFX 11.0 commercial code was done for proper design of the heat exchanger. The present experimental studies were also conducted to investigate the effects of circulating solid particles on the characteristics of fluid flow, heat transfer and cleaning effect in the fluidized bed vertical shell and tube type heat exchanger with counterflow, at which a variety of solid particles such as glass ($3mm{\Phi}$), aluminum ($2{\sim}3mm{\Phi}$), steel ($2{\sim}2.5mm{\Phi}$), copper ($2.5mm{\Phi}$) and sand ($2{\sim}4mm{\Phi}$) were used in the fluidized bed with a smooth tube. Seven different solid particles have the same volume, and the effects of various parameters such as water flow rates, particle diameter, materials and geometry were investigated. The present experimental and numerical results showed that the flow velocity range for collision of particles to the tube wall was higher with heavier density solid particles, and the increase in heat transfer was in the order of sand, copper, steel, aluminum, and glass. This behavior might be attributed to the parameters such as surface roughness or particle heat capacity.

• Corrosion Science and Technology
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• 제22권5호
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• pp.322-329
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• 2023

There are a variety of heat exchangers used in automobiles, such as shell and tube heat exchangers, double tube heat exchangers, and plate heat exchangers. Most of them are water-cooled to prevent engine overheating. There have been reports of corrosion damage to these heat exchangers due to continuous wetting caused by external temperature differences, road pollutants, and snow removal. In addition, galvanic corrosion, which occurs when two dissimilar materials come into contact, has been identified as a major cause. In this study, corrosion characteristics and galvanic corrosion behavior of Al alloy (AA3003, AA4045 and AA7072) used in automobile heat exchangers were analyzed. Effective clad materials for heat exchanger tubes and fins were also evaluated. It was found that AA7072 should be applied as the cladding material for fin AA3003 and that AA4045 was suitable as a cladding material for tube AA3003 because this clad materials application was the most effective clad design to delay the occurrence of pinhole in the tube. Main factors influencing galvanic corrosion dissolution were found to be galvanic corrosion potential difference and galvanic corrosion current density.

• 설비공학논문집
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• 제24권8호
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• pp.621-626
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• 2012

A new baffle configuration, an annular baffles, are considered in the present study as an alternative to reduce the excessive pressure drop associated with the conventional segmental ones in typical operating conditions. The heat transfer and pressure drops are numerically simulated for a single tube shell-and-tube model and compared against the conventional-baffle cases. Baffle blockage ratio and number of baffles are considered as the major variables for the present study specifying a fixed baffle spacing. It is found that the heat transfer increases 1.4~2.2 times without significant pressure loss compared to the bare tube cases and the goodness factor increases 1.35 times compared to the conventional-baffle model.

• 설비공학논문집
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• 제17권12호
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• pp.1132-1138
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• 2005

Recently, production and use of freon substances are restrained due to depletion of ozone layer and global warming. In this aspect of environmental problems, the best solution is to use the natural refrigerant such as ammonia. Thus, this study is to find the optimal operating conditions by comparing the performance between the shell and tube type and shell and disk type heat exchangers using the ammonia refrigerant, and to verify the superiority of the shell and disk type heat exchanger that is not used in field of refrigeration and air conditioning. Finally, this study shows that the shell and disk type heat exchanger is applicable to the ammonia refrigeration system, and this system minimizes the refrigerant charge and installation space.

• 대한기계학회논문집B
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• 제39권3호
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• pp.223-229
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• 2015

배플과 관군간의 누설유동이 쉘-관 열교환기 성능에 미치는 영향을 FLUENT 를 사용하여 조사하였다. 쉘측 출구온도를 최대로 하는 최적누설유동을 찾기 위해 쉘측 단면적에 대한 누설단면적 비가 0%-40% 범위의 5 가지 누설유동을 가진 쉘-관 열교환기에 대하여 CFD 모델이 개발되었다. 관 입구 및 벽면온도를 일정하게 유지하고 Reynolds 수를 4952 부터 14858 증가시키면서 유동장 및 온도장을 계산하였다. 해석결과, 출구온도, 압력강하, 열전달률은 Reynolds 수뿐만 아니라 누설유동에도 크게 영향을 받는 것으로 나타났다. 누설유동은 열전달률과 압력강하를 동시에 낮추는 결과를 제시한 기존의 결과와는 달리, 본 연구에서는 적정의 누설유동은 배플 주위의 재순환영역에 추가적인 모멘텀을 공급함으로써 최대출구온도, 작은 압력강하, 높은 열전달률을 유도하는 효과를 발휘하는 새로운 결과를 얻었다. 20%의 누설단면적이 최적의 누설단면적으로 나타났다.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2011년도 춘계학술발표대회 논문집
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• pp.74-79
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• 2011

This study was accomplished to evaluate the performance of Multi Effect Distillation(MED) for solar thermal desalination system. It was designed Multi effect distillation with $3m^3/day$ capacity and Shell&Tube type heat exchanger. Also, The effective heat transfer of Shell&Tube heat exchanger was used Cu(90%)-Ni(10%) corrugated tube. The parameters relating to the performance of Multi Effect Distillation are known as hot water flow rate. The experimental conditions for each parameters were $18^{\circ}C$ for sea water inlet temperature, $6m^3/hour$ sea water inlet volume flow rate, $75^{\circ}C$ for hot water inlet temperature, 2.4, 3.6, and $4.8m^3/hour$ for hot water inlet volume flow rate, respectively. The results are as follows, Development for Multi effect distillation was required about 40kW heat and 35kW cooling source to produce $3m^3/day$ of fresh water. And, Performance ratio of Development Multi effect distillation was about 2.0191.