• Title/Summary/Keyword: Heat leak

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Modeling of non-isothermal CO2 particle leaked from pressurized source: II. Behavior of single droplet

  • Chang, Daejun;Han, Sang Heon;Yang, Kyung-Won
    • Ocean Systems Engineering
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    • v.2 no.1
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    • pp.33-47
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    • 2012
  • This study revealed the behavior of droplets formed through leak process in deep water. There was a threshold depth named the universal attraction depth (UAD). Droplets rose upward in the zone below the UAD called the rising zone, and settled down in the zone above the UAD called the settling zone. Three mass loss modes were identified and formulated: dissolution induced by mass transfer, condensation by heat transfer and phase separation by pressure decrease. The first two were active for the settling zone, and all the three were effective for the rising zone. In consequence, the life time of the droplets in the rising zone was far shorter than that of the droplets in the settling zone.

A Study on the Contact Force and Temperature Distribution of Lip Seals (립실의 접촉력 및 온도분포 해석에 관한 연구)

  • 김청균;전인기;김종억
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.6
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    • pp.1559-1566
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    • 1994
  • Using the finite element method, the contact force, contact band width and temperature distribution of lip seals analyzed for the interference including some nonlinearities such as material nonlinearity, geometrical nonlinearity and nonlinear contact boundary condition. The calculated results showed that the contact stress concentrated on the contact zone between the garter spring and the rubber toward the flex side, the contact edge of lip seals. The high contact forces due to the increased interference separate the sealing gap between the lip edge and the rotating shaft. This may lead to leak the sealed oil.

The Characteristic Investigation on Narrow-gap TIG Weld Joint of Heavy wall Austenitic Stainless Steel Pipe (오스테나이트계 SS 배관의 협개선 TIG 용접부 특성 조사)

  • Shim, Deog-Nam;Jung, In-Cheol
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.670-677
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    • 2003
  • Although Gas Tungsten Arc Welding (GTAW or TIG welding) is considered as high quality and precision welding process, it also has demerit of low melting rate. Narrow-gap TIG welding which has narrow joint width reduces the groove volume remarkably, so it could be shorten the welding time and decrease the overall shrinkage in heavy wall pipe welding. Generally Narrow-gap TIG welding is used as orbital welding process, it is important to select the optimum conditions for the automatic control welding This paper looks at the application and metallurgical properties on Narrow-gap TIG welding joint of heavy wall large austenitic stainless steel pipe to determine the deposition efficiency, the resultant shrinkage and fracture toughness. The fracture toughness depends slightly on the welding heat input.

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Effect of Vapor-Cooled Heat Stations in a Cryogenic Vessel (극저온액체 저장용기에서 열전도 차폐단의 영향)

  • Kim, S.Y.;Kang, B.H.;Choi, H.J.
    • Transactions of the Korean hydrogen and new energy society
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    • v.9 no.4
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    • pp.169-176
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    • 1998
  • An experimental study on effect of vapor-cooled heat stations in a 5.5 liter cryogenic vessel has been performed. The cryogenic vessel is made of stainless steel of thickness of 1mm and insulated by the combined insulation of vacuum, MLI(multi-layer insulation) and vapor-cooled radiation shield. Vapor-cooled heat stations are also constructed based on the 1-dimensional thermal analysis to reduce the heat inleak through a filling tube. Thermal analysis indicates that the vapor-cooled heat stations can substantially enhance the performance of vessel for cryogenic fluids with high $C_p/h_{fg}$ where $C_p$ the specific heat and $h_{fg}$ the heat of vaporization, such as $LH_2$ and LHe. The experimental results for $LN_2$ shows that the total heat inleak into inner vessel consists of 14% radiation and 86% conduction through the filling tube. Therefore, it is expected that the conduction heat in leak of the vessel for high $C_p/h_{fg}$ cryogenic fluids can be significantly reduced. powders. The amount of copper coating was 20wt%. In order to examine corrosion behavior of the electrodes, the corrosion current and the current density, in 6M KOH aqueous solution after removal of oxygen in the solution, were measured by potentiodynamic and cyclic voltamo methods. The results showed that Co in the alloy increased corrosion resistance of the electrode whereas Ni decreased the stability of the electrode during the charge-discharge cycles. The electrode used Si sealant as a binder showed a lower corrosion current density than the electrode used PTFE and the electrode used Cu-coated alloy powders showed the best corrosion resistance.

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A Study of Damage Assessment Caused by Hydrogen Gas Leak in Tube Trailer Storage Facilities (수소 Tube Trailer 저장시설에서의 수소가스 누출에 따른 사고피해예측에 관한 연구)

  • Kim, Jong-Rak;Hwang, Seong-Min;Yoon, Myong-O
    • Fire Science and Engineering
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    • v.25 no.6
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    • pp.32-38
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    • 2011
  • As the using rate of an explosive gas has been increased in the industrial site, the regional residents adjacent to the site as well as the site workers have frequently fallen into a dangerous situation. Damage caused by accident in the process using hydrogen gas is not confined only to the relevant process, but also is linked to a large scale of fire or explosion and it bring about heavy casualties. Therefore, personnel in charge should investigate the kinds and causes of the accident, forecast the scale of damage and also, shall establish and manage safety countermeasures. We, in Anti-Calamity Research Center, forecasted the scope of danger if break out a fire or/and explosion in hydrogen gas facilities of MLCC firing process. We selected piping leak accident, which is the most frequent accident case based on an actual analysis of accident data occurred. We select and apply piping leak accident which is the most frequent case based on an actual accident data as a model of damage forecasting scenario caused by accident. A jet fire breaks out if hydrogen gas leaks through pipe size of 10 mm ${\Phi}$ under pressure of 120 bar, and in case of $4kw/m^2$ of radiation level, the radiation heat can produce an effect on up to distance of maximum 12.45 meter. Herein, we are going to recommend safety security and countermeasures for improvement through forecasting of accident damages.

Failure Analysis on Localized Corrosion of Heat Transport Pipe in District Heating System (지역난방 열수송관 국부 부식 파손 분석)

  • Kim, You Sub;Chae, Hobyung;Kim, Woo Cheol;Jeong, Joon Cheol;Kim, Heesan;Kim, Jung-Gu;Lee, Soo Yeol
    • Corrosion Science and Technology
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    • v.19 no.3
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    • pp.122-130
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    • 2020
  • In this study, a corrosion failure analysis of a heat transport pipe was conducted, as the result of a pinhole leak. Interestingly, the corrosion damage occurred externally in the pipeline, resulting in severe thickness reduction near the seam line. Also, while a stable magnetite protective film formed on the inner surface, the manganese oxide formation occurred only on the outer surface. The interior and exterior of the pipe were composed of ferrite and pearlite. The large manganese sulfide and alumina inclusions were found near the seam line. In addition, the manganese sulfide inclusions resulted in grooving corrosion, which progressed in the seam line leading to the reduction in the thickness, followed by the exposure of the alumina in the matrix to the outer surface. To note, the corrosion was accelerated by pits generated from the boundaries separating the inclusions from the matrix, which resulted in pinhole leaks and water loss.

Efficacious Pleurodesis with OK-432 Plus Autoblood or OK-432 Against the Pneumothorax with Persistent Air Leak (지속성 기흉에서 OK-432와 자가혈액을 이용한 흉막 유착술의 효과)

  • Kim, Hyoung Soo;Choi, Goang Min
    • Tuberculosis and Respiratory Diseases
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    • v.60 no.1
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    • pp.72-75
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    • 2006
  • Background : This report reviews our experience with persistent air leaks in the peumothorax that were not considered candidates for surgical treatment in order to evaluate the efficacy and risks of the OK-432 plus autoblood or OK-432 pleurodesis. Material & Methods : From March 2004 to July 2005, 8 consecutive patients who had an air leak in the pneumothorax over 5 days and had been treated with OK-432 plus autoblood or OK-432 pleurodesis. The patients were not considered candidates for surgical treatments because the chest CT findings revealed severe chronic lung disease with multiple bullae and/or bullous changes. A prolonged air leak with/without dead space was treated with either OK-432 plus autoblood or OK-432 pleurodesis. The efficacy and side effects of OK-432 pleurodesis were assessed by determining the duration of the air leak, the number of pleurodesis, the patients' symptoms, measurements of the white blood cell count and the c-reactive protein level. Results : All of eight patients were male and the mean age was $72.4{\pm}8.5$. The mean number of pleurodesis was $1.9{\pm}1.1$ and the mean duration of the air leak was $4.6{\pm}4.6days$ after pleurodesis. Side effects after pleurodesis were encountered in 7 patients, which included a chilling sensation in 7 cases, chest pain in 5 cases, headache in 3 cases, local heat sensation in 2 cases, and fever in 1 case. Leukocytosis was observed in 6 patients, and the mean of WBC count and CRP were $14500{\pm}2100$ and $21.9{\pm}11.4mg/dL$, respectively. Conclusion : Either OK-432 plus autoblood or OK-432 pleurodesis has acceptable side effects, and can be considered a treatment option for persistent air leaks in the pneumothorax that are not candidates for surgical treatment.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2013 (설비공학 분야의 최근 연구 동향 : 2013년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.26 no.12
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    • pp.605-619
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    • 2014
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2013. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of fluid machinery, pipes and relative parts including orifices, dampers and ducts, fuel cells and power plants, cooling and air-conditioning, heat and mass transfer, two phase flow, and the flow around buildings and structures. Research issues dealing with home appliances, flows around buildings, nuclear power plant, and manufacturing processes are newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for general analytical model for desiccant wheels, the effects of water absorption on the thermal conductivity of insulation materials, thermal properties of Octadecane/xGnP shape-stabilized phase change materials and $CO_2$ and $CO_2$-Hydrate mixture, effect of ground source heat pump system, the heat flux meter location for the performance test of a refrigerator vacuum insulation panel, a parallel flow evaporator for a heat pump dryer, the condensation risk assessment of vacuum multi-layer glass and triple glass, optimization of a forced convection type PCM refrigeration module, surface temperature sensor using fluorescent nanoporous thin film. In the area of pool boiling and condensing heat transfer, researches on ammonia inside horizontal smooth small tube, R1234yf on various enhanced surfaces, HFC32/HFC152a on a plain surface, spray cooling up to critical heat flux on a low-fin enhanced surface were actively carried out. In the area of industrial heat exchangers, researches on a fin tube type adsorber, the mass-transfer kinetics of a fin-tube-type adsorption bed, fin-and-tube heat exchangers having sine wave fins and oval tubes, louvered fin heat exchanger were performed. (3) In the field of refrigeration, studies are categorized into three groups namely refrigeration cycle, refrigerant and modeling and control. In the category of refrigeration cycle, studies were focused on the enhancement or optimization of experimental or commercial systems including a R410a VRF(Various Refrigerant Flow) heat pump, a R134a 2-stage screw heat pump and a R134a double-heat source automotive air-conditioner system. In the category of refrigerant, studies were carried out for the application of alternative refrigerants or refrigeration technologies including $CO_2$ water heaters, a R1234yf automotive air-conditioner, a R436b water cooler and a thermoelectric refrigerator. In the category of modeling and control, theoretical and experimental studies were carried out to predict the performance of various thermal and control systems including the long-term energy analysis of a geo-thermal heat pump system coupled to cast-in-place energy piles, the dynamic simulation of a water heater-coupled hybrid heat pump and the numerical simulation of an integral optimum regulating controller for a system heat pump. (4) In building mechanical system research fields, twenty one studies were conducted to achieve effective design of the mechanical systems, and also to maximize the energy efficiency of buildings. The topics of the studies included heating and cooling, HVAC system, ventilation, and renewable energies in the buildings. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment is mostly focused on indoor environment and building energy. The main researches of indoor environment are related to infiltration, ventilation, leak flow and airtightness performance in residential building. The subjects of building energy are worked on energy saving, operation method and optimum operation of building energy systems. The remained studies are related to the special facility such as cleanroom, internet data center and biosafety laboratory. water supply and drain system, defining standard input variables of BIM (Building Information Modeling) for facility management system, estimating capability and providing operation guidelines of subway station as shelter for refuge and evaluation of pollutant emissions from furniture-like products.

Temperature and Flow Velocity Analysis for Fire in Synthetic Heat Transfer Fluid Boiler (열매유 보일러 내부화재에 따른 온도 및 속도분포 해석)

  • Kim, Yeob-Rae;Son, Bong-Sei
    • Fire Science and Engineering
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    • v.27 no.5
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    • pp.19-25
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    • 2013
  • The fire took place in the synthetic heat transfer fluid boiler. This study uses simulation to investigate the first, second and third passes and the temperature in the fire burner. The boiler's internal fluid is more or less unsteady due to the out of order inverter. As the operation continues, the flame's flow and speed are unsteady. The synthetic heat transfer fluid leak spouted about 120 kg/min in the form of vapor in the early period of the fire. The flame extended to the second and third passes. The highest temperature of the second and third pass is $1059^{\circ}C$ and $1007^{\circ}C$, respectively. The simulation shows that the temperature is $767^{\circ}C$ in the low part of the third pass. The synthetic heat transfer fluid spouted through the cracked part of the fire box in the first pass and accumulated on the turn table. The temperature rises to $183^{\circ}C$ in the low part of the burner. Therefore, it is expected that the temperature of the interior of the fire box is above $1200^{\circ}C$. The temperature of the burner rises to a maximum level several times in a short period. On account of that, several explosions occur in the fire burner.

A study on damage prediction analysis for styrene monomer fire explosion accidents (스티렌 모노머 화재폭발사고 피해예측 분석에 관한 연구)

  • Hyung-Su Choi;Min-Je Choi;Guy-Sun Cho
    • Industry Promotion Research
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    • v.9 no.2
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    • pp.37-44
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    • 2024
  • This study selected the worst-case scenario for fireball and vapor cloud explosion (VCE) of a styrene monomer storage tank installed in a petrochemical production plant and performed damage prediction and accident impact analysis. The range of influence of radiant heat and overpressure due to fireball and vapor VCE during the abnormal polymerization reaction of styrene monomer, the main component of the mixed residue oil storage tank, was quantitatively analyzed by applying the e-CA accident damage prediction program. The damage impact areas of radiant heat and explosion overpressure are analyzed to have a maximum radius of 1,150m and 626m, respectively. People within 1,150m of radiant heat of 4kW/m2 may have their skin swell when exposed to it for 20 seconds. In buildings within 626m, where an explosion overpressure of 21kPa is applied, steel structures may be damaged and separated from the foundation, and people may suffer physical injuries. In the event of a fire, explosion or leak, determine the risk standards such as the degree of risk and acceptability to workers in the work place, nearby residents, or surrounding facilities due to radiant heat or overpressure, identify the hazards and risks of the materials handled, and establish an emergency response system. It is expected that it will be helpful in establishing measures to minimize damage to workplaces through improvement and investment activities.