• Title/Summary/Keyword: Horizontal small tube

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A Study on Manufacturing and Experimental Techniques for the 1/5th Scale Model of Precast Concrete Large Panel Structure (프리캐스트 콘크리트 대형판 구조물의 1/5축소모델 제작 및 실험기법 연구)

  • 이한선;김상규
    • Magazine of the Korea Concrete Institute
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    • v.8 no.2
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    • pp.139-150
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    • 1996
  • The objective of this study is to provide the information on the manufacturing and exper- , ructures. imental techniques of small scale modeling of precast concrete(P.C.) large panel :-t The ad~~pted scale was one-fifth. 4 types of experiments were performed : nlaterial tests for model concrete and model reinforcement, compressive test of horizontal joint, shear test of vertical joint and cyclic static test of 2-story subassemblage structure. Based on the experimental results, the following conclusions are drawn : i 1) Model concrete had in general larger compressive strength than expected. (2) Model reinforcement showed less ductility if the annealing processes were performed without using vaccuum tube. 131 Failure niotles of horizontal and vertical joints were almost same for both prototype and model. But the strength of model appears to be higher than required by similitude law. (41 Hysteretic behavior of 1 /T, scale subassemblage model can be made quite similar to that of prototype if the ductility of model reinforcement and compressive strength of model concrete could be representative of those of prototype.

Characteristics of Evaporation Heat Transfer in a Small-Scale Cryogenic Heat Exchange System for the Utilization of LNG Cold Energy (LNG 냉열활용을 위한 초저온 열교환시스템의 축소모형에서 증발 열전달 특성)

  • Nam S. C.;Lee S. C.;Lee Y. W.;Sohn Y. S.
    • Journal of the Korean Institute of Gas
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    • v.2 no.4
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    • pp.25-33
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    • 1998
  • The characteristics of evaporation heat transfer for the utilization of LNG cold energy was investigated experimentally using liquified nitrogen and a solution of ethylene-glycol and water under horizontal two-phase conditions in the small-scale equipment of a cryogenic heat exchange system. The inner tubes in the double pipe heat exchanger with 8 mm and 15 mm inner diameter and 6 m length were adopted as a smooth test tubes and enhanced tubes by means of wire-coil inserts. Heat transfer coefficients and Nusselt number for the test tube were calculated from measurements of temperatures, flowrates and pressures. The correlations in a power-law relationship of the Nusselt number, the Reynolds number and Prandtl number for heat transfer were proposed which can be available for design of cryogenic heat exchangers. The correlations showed heat transfer coefficients for the wire-coil inserts were much higher than those for the smooth tubes, increased by more than 2.5 ${\~}$ 5.5 times depending upon the equivalent Reynolds number. Form and length of cryogenic double pipe heat exchanger were proposed for applicable to the utilization of LNG cold energy.

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Performance Evaluation of Underground Pipe with In-Situ Recycled Controlled Low Strength Materials (현장발생토사 재활용 유동성채움재를 이용한 지하매설관의 거동평가)

  • Lee Kwan-Ho;Song Chang-Seob
    • International Journal of Highway Engineering
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    • v.8 no.2 s.28
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    • pp.1-12
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    • 2006
  • An existing Steel pipe, Cast iron pipe and Concrete pipe is can not escaped from aging, specially Metal tube is causing many problems that the quality of water worse is concerned about many rust and mike efficient use of preservation of water. The use of Glassfiber Reinforced Plastic Pipe(GRP PIPE) should be one of the possible scheme to get over these problems. The GRP PIPE has an excellent resistance power and the life is lasting from 50 to 100 years roughly. It's to be useful as a result of high durability and a good construction work also it is a light weight therefore can be expected to short the time of construction and man power. In this research, to executed the small-scaled model test, in-situ model test using CLSM of in-situ soil and to evaluated the stress - strain of the pipe also try to estimated how useful is. From the model test in laboratory, the vertical and horizontal deformation of the GRP PIPE measured in six instance using 200mm and 300mm in diameters. The value of experimentation, theory, analysis got the same results of the test, but the vertical and horizontal deformation gauged in small and the earth pressure was almost zero using CLSM of in-situ soil..

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Condensation Heat Transfer Characteristics of R-410A as an Alternative R-22 in the Condenser with Small Diameter Tubes (세관을 사용한 응축기에서 R-22의 대체냉매인 R-410A의 응축 열전달 특성)

  • Son, Chang-Hyo
    • Clean Technology
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    • v.13 no.2
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    • pp.151-158
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    • 2007
  • An experimental study to investigate the condensing heat transfer characteristics of small diameter horizontal double pipe heat exchangers with R-22 and R-410A was performed. Experimental facility was constructed to calculate and observe HTC(heat transfer coefficients), flow patterns and pressure drop. The main components include a liquid pump, an evaporator, a condenser(test section), a sight-glass, pressure taps and measurement apparatus. Two pipes of different diameters are tested; One 5.35 mm ID 0.5 mm thick, the other 3.36 mm ID 0.7 mm thick. The mass flow rate ranged from 200 to $500\;ks/m^2{\cdot}s$ and heating capacity were form 1.0 to 2.4 kW. The flow patterns of R-22 and R-410A were observed with a high speed camera through the sight-glass. The tests revealed that HTC of R-410A was higher than that of R-22 by maximum 5%. Annular pattern was observed for the most cases but stratified flow was also detected when x<0.2. The pressure drop in 3.36 mm ID pipe was higher than that of 5.35 mm by $30{\sim}50%$. Comparing with previous correlations such as Shah, Fujii and Soliman's, Fujii' showed the best good agreement with my data with a maximum deviation of 40%.

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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.

Monte Carlo Simulations of Detection Efficiency and Position Resolution of NaI(TI)-PMT Detector used in Small Gamma Camera (소형 감마카메라 제작에 사용되는 NaI(TI)- 광전자증배관 검출기의 민감도와 위치 분해능 특성 연구를 위한 몬테카를로 시뮬레이션)

  • Kim, Jong-Ho;Choi, Yong;Kim, Jun-Young;Im, Ki-Chun;Kim, Sang-Eun;Choi, Yeon-Sung;Joo, Kwan-Sik;Kim, Young-Jin;Kim, Byung-Tae
    • Progress in Medical Physics
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    • v.8 no.2
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    • pp.67-76
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    • 1997
  • We studied optical behavior of scintillation light generated in NaI(TI) crystal using Monte Carlo simulation method. The simulation was performed for the model of NaI(TI) scintillator (size: 60 mm ${\times}$ 60 mm ${\times}$ 6 mm) using an optical tracking code. The sensitivity as a function of surface treatment (Ground, Polished, Metal-0.95RC, Polished-0.98RC, Painted- 0.98RC) of the incident surface of the scintillator was compared. The effects of NaI(TI) scintillator thickness and the refractive index of light guide optically coupling between the NaI(TI) scintillator and photomultiplier tube (PMT) were simulated. We also evaluated intrinsic position resolution of the system by calculating the spread of scintillation light generated. The sensitivities of the system having the surface treatment of Ground, Polished, Metal-0.95RC, Polished-0.98RC and Painted-0.98RC were 70.9%, 73.9%, 78.6%, 80.1% and 85.2%, respectively, and the surface treatment of Painted-0.98RC allowed the highest sensitivity. As increasing the thickness of scintillation crystal and light guide, the sensitivity of the system was decreased. As the refractive index of light guide increases, the sensitivity was increased. The intrinsic position resolution of the system was estimated to be 1.2 mm in horizontal and vertical directions. In this study, the performance of NaI(TI)-PMT detector system was evaluated using Monte Carlo simulation. Based on the results, we concluded that the NaI(TI)-PMT detector array is a favorable configuration for small gamma camera imaging breast tumor using Tc-99m labeled radiopharmaceuticals.

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Morphological Adaptation of Zostera marina L. to Ocean Currents in Korea (한국산 거머리말(Zostera marina L.)의 해류에 대한 형태적 적응)

  • Lim, Dong-Ok;Yun, Jang-Tak;Han, Kyung-Shik
    • Korean Journal of Environment and Ecology
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    • v.23 no.5
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    • pp.431-438
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    • 2009
  • The main purpose of this research is to prepare and provide basic materials for the propagational strategy of eelgrass by investigating on the morphological adaptation of Korean Zostera marina to ocean currents. An eelgrass plant mainly consists of rhizome, leaf sheath, leaves and roots. The rhizome is the horizontal stem of the plant that serves as the backbone from which the leaves and roots emerge. The leaf sheath is the bundle at the base of the leaves that holds the leaves together, protecting the meristem, the primary growth point of the shoot. Leaves originate from a meristem which is protected by a sheath at the actively growing end of the rhizome. As the shoot grows, the rhizome elongates, moving across or within the sediment, forming roots as it progresses. The aggregated leaves from the leaf sheath are found to have two cell layers on one side and multiple layers of airy tissues called aerenchyma on the other. The aerenchyma tissues are developed in multi-layered cell structures surrounding the veins which are formed in the leaf sheath. Generative shoots are made of rhizomes, which are circular or ovoidal, stem, and spathe and spadix. The transverse section of rhizome and the stem and central floral axis is found to be circular, ovoid and in the shape of convex respectively, and the vascular bundle, which is a part of transport system, has one large tube in the center and two small tubes on both sides. The layers of collenchyma cells numbered from 12 to 15 in the stem, and from 7 to 12 in the rhizome. The seed coat is composed of sclereids, small bundles of sclerenchyma tissues, which prevent the influx of sea water from the outside and help endure the environmental stress. In conclusion, alternative multi-layer structure in circular, convex type aggregated leaf base are interpreted to morphological adaption as doing tolerable elastic structure through movement of seawater. The generative shoots develop long slim stem and branches in circular or ovoidal shapes to minimize the adverse impacts of sea current, which can be interpreted as the plant's morphological adaptation to its environment.