• Title/Summary/Keyword: center pipe

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Titanium alloys: A closer-look at mechanical, gamma-ray, neutron, and transmission properties of different grade alloys through MCNPcode application

  • Ghada ALMisned;Omer Guler;Duygu Sen Baykal;G. Kilic;H.O. Tekin
    • Nuclear Engineering and Technology
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    • v.56 no.9
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    • pp.3501-3511
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    • 2024
  • Titanium alloys play a vital role in optimizing the effectiveness and security of nuclear reactors, strengthening structural durability, and facilitating the effective handling of nuclear waste. The aim of this study is to investigate the gamma-ray, neutron, and transmission properties of four common titanium alloys through the examination of the deposited energy amount in the liquid sodium coolant material, in relation to the mechanical properties of these alloys. MCNP (version 6.3) is utilized for designing the titanium pipes. Next, the pipes were re-designed considering the elemental mass fractions and densities of the investigated titanium alloys. Grade 26 sample is reported with the highest values of mass attenuation coefficients and the lowest HVL values among those investigated alloys. Grade 26 is reported to have the lowest TF value, whereas Grade 12 demonstrated the highest TF value. The highest Effective Removal Cross Section (ΣR, 1/cm) value against fast neutrons is reported for Grade 26. The utilization of Grade 26 sample as pipe material resulted in the lowest deposited energy amount (MeV/g) and subsequent lowest contamination in the coolant material. Out of the alloys that were chosen for analysis, it has been determined that Grade 26 exhibits the highest level of strength. It can be concluded that the Grade 26 alloy exhibits desirable characteristics for applications in nuclear technologies that require superior gamma-ray and neutron absorption properties, as well as exceptional mechanical properties. Nevertheless, it is essential to emphasize the importance for ongoing studies to enhance the existing material properties of Grade 26, with the aim of achieving improved safety and efficacy in nuclear applications.

A Study on the Cold Flow Characteristics of a Flue Gas Recirculation Burner with Both Outlets Opening (양쪽 출구가 트인 배기가스 재순환 버너의 냉간 유동 특성에 관한 연구)

  • Ha, Ji Soo
    • Journal of the Korean Institute of Gas
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    • v.22 no.3
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    • pp.7-12
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    • 2018
  • Thermal NOx is generated in a high temperature environment in a combustion facilities. Exhaust gas recirculation method is widely used among various methods for reducing nitrogen oxides in combustion devices. In the present study, the computational fluid dynamic analysis was accomplished to elucidate the cold flow characteristics in the flue gas recirculation burner with both outlets opening. Because the reciculation pipes is installed toward the tangential direction, the swirling flow is formulated in the burner and the phenomenon of the reverse flow creation is detected at the center area of circular burner. We are confirmed that this is the similar trend with the burner with one side outlet closed. From the present study, it was seen that the recirculated inflow from both recirculated burner outlets increased by about 5% compared to the burner with one side outlet opening. At the outlet located at the exhaust gas recirculation pipe inlet(gas exit 1), the inlet flow was formed in the entire region. At the opposite outlet(gas exit 2), the total flow was discharged, but the center part of the burner was observed to have a reverse flow. The flow rate at the gas exit 2 was 3 ~ 5 times larger than the flow rate at the gas exit 1.

Analytic study on thermal management operating conditions of balance of 100kW fuel cell power plant for a fuel cell electric vehicle (100kW급 연료전지 열관리 시스템 실도로 운전조건 해석적 연구)

  • Lee, Ho-Seong;Lee, Moo-Yeon;Cho, Choong-Won
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.2
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    • pp.1-6
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    • 2019
  • The objective of this study was to investigate performance characteristics of thermal management system(TMS) in a fuel cell electric vehicle with 100kW Fuel Cell(FC) system. In order to build up analytic modelling for TMS, each component was installed and tested under various operating conditions, such as water pump, radiator, 3-Way valve, COD heater, and FC stack etc. and as the results of them, correlations reflecting component's characteristics with flow rate, air velocity were developed. Developed analytic modelling was carried out under various operating conditions on the road. To verify modelling's accuracy, after prediction for optimum coolant flow rate was fulfilled under certain operating conditions, such as FC system, water pump speed, opening of 3-way valve, and pipe resistance, analytic and experimental values were compared and good agreement was shown. In order to predict cold-start operating performance for analytic modelling, coolant temperature variation was analyzed with $-20^{\circ}C$ ambient temperature and duration was predicted to rise in optimum temperature for FC. Because there is appropriate temperature difference between inlet and outlet of FC stack to operate FC system properly, related analysis was performed with respect to power consumption for TMS and heat rejection rate and performance map was depicted along with FC operating conditions.

A Study of Hydrodynamics and Reaction Characteristics in Relation to the Desulfurization Temperatures of Zn-Based Solid Sorbent in the Lab-scale High Pressure and High Temperature Desulfurization Process (실험실규모 고온고압건식탈황공정의 수력학적 특성 및 탈황온도에 따른 아연계 탈황제의 반응특성 연구)

  • Kyung, Dae-Hyun;Kim, Jae-Young;Jo, Sung-Ho;Park, Young Cheol;Moon, Jong-Ho;Yi, Chang-Keun;Baek, Jeom-In
    • Korean Chemical Engineering Research
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    • v.50 no.3
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    • pp.492-498
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    • 2012
  • In this study, hydrodynamics such as solid circulation rate and voidage in the desulfurizer and the reaction characteristics of Zn-based solid sorbents were investigated using lab-scale high pressure and high temperature desulfurization process. The continuous HGD (Hot Gas Desulfurization) process consist of a fast fluidized bed type desulfurizer (6.2 m tall pipe of 0.015 m i.d), a bubbling fluidized bed type regenerator (1.6 m tall bed of 0.053 m i.d), a loop-seal and the pressure control valves. The solid circulation rate was measured by varying the slide-gate opening positions, the gas velocities and temperatures of the desulfurizer and the voidage in the desulfurizer was derived by the same way. At the same gas velocities and the same opening positions of the slide gate, the solid circulation rate, which was similar at the temperature of $300^{\circ}C$ and $550^{\circ}C$, was low at those temperatures compared with a room temperature. The voidage in the desulfurizer showed a fast fluidized bed type when the opening positions of the slide gate were 10~20% while that showed a turbulent fluidized bed type when those of slide gate were 30~40%. The reaction characteristics of Zn-based solid sorbent were investigated by different desulfurization temperatures at 20 atm in the continuous operation. The $H_2S$ removal efficiency tended to decrease below the desulfurization temperature of $450^{\circ}C$. Thus, the 10 hour continuous operation has been performed at the desulfurization temperature of $500^{\circ}C$ in order to maintain the high $H_2S$ removal efficiency. During 10 hour continuous operation, the $H_2S$ removal efficiency was above 99.99% because the $H_2S$ concentration after desulfurization was not detected at the inlet $H_2S$ concentration of 5,000 ppmv condition using UV analyzers (Radas2) and the detector tube (GASTEC) which lower detection limit is 1 ppmv.

Experimental Study for Confirmation of Relaxation Zone in the Underground Cavity Expansion (지중 내 공동 확장에 따른 이완영역 확인을 위한 실험적 연구)

  • Kim, Youngho;Kim, Hoyeon;Kim, Yeonsam;You, Seung-Kyong;Han, Jung-Geun
    • Journal of the Korean Geosynthetics Society
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    • v.16 no.4
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    • pp.231-240
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    • 2017
  • Recently, there have been frequent occurrences of ground sink in the urban area, which have resulted in human and material damage and are accompanied by economic losses. This is caused by artificial factors such as soil loss, poor compaction, horizontal excavation due to the breakage of the aged sewage pipe, and lack of water proof at vertical excavation. The ground sink can be prevented by preliminary restoration and reinforcement through exploration, but it can be considered that it is not suitable for urgent restoration by the existing method. In this study, a model experiment was carried out to simulate the in-ground cavities caused by groundwater flow for developing non-excavation urgent restoration in underground cavity and the range of the relaxation zone was estimated by detecting the around the cavity using a relaxation zone detector. In addition, disturbance region and relaxation region were separated by injecting gypsum into cavity formed in simulated ground. The shape of the underground cavity due to the groundwater flow was similar to that of the failure mode III formed in the dense relative density ground due to water pipe breakage in the previous study. It was confirmed that the relaxed region detected using the relaxation zone detector is formed in an arch shape in the cavity top. The length ratio of the relaxation region to the disturbance region in the upper part of the cavity center is 2: 1, and it can be distinguished by the difference in the decrease of the shear resistance against the external force. In other words, it was confirmed that the secondary damage should not occur in consideration of the expandability of the material used as the injecting material in the pre-repair and reinforcement, and various ground deformation states will be additionally performed through additional experiments.

The Optimum Specification of Pipes in Rain-Sheltering Greenhouse with Roof Vents for Large-Grain Grapevine Cultivation (대립계 포도 천창개폐형 비가림하우스의 최적 파이프 규격)

  • Yum, Sung-Hyun;Yun, Nam-Gyu;Kim, Gyeong-Won;Lee, Sung-Hyoun;Cho, Yong-Ho;Park, Seo-Jun;Park, Mun-Kyun
    • Journal of Bio-Environment Control
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    • v.16 no.4
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    • pp.275-283
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    • 2007
  • This study was carried out to: (1) analyze structural stability of representative rain-sheltering greenhouses for large-grain grapevine cultivation with widths of 3.6 m and 5 m in case of using the existing pipe for agriculture; (2) present the optimum specification of pipes in the greenhouse with a width of 5 m under the condition of using the pipe of which ultimate strength has been above $400N{\cdot}mm^{-2}$; (3) evaluate stability and also present the optimum specification of pipes as eaves height was augmented. The above analyses were done for greenhouses with roof vents and also with a main-column interval of 3 m and a rafter interval of 60 cm. First, the existing 3.6 m greenhouse with a rafter of ${\Phi}25.4{\times}1.5t@600$ was stable far a snow-depth of 35 cm but unstable for a wind velocity of $35m{\cdot}s^{-1}$. Meanwhile the existing 5 m greenhouse with the same rafter was not stable for a wind velocity of $335m{\cdot}s^{-1}$ as well as a snow-depth of 35 cm. This meant that existing greenhouses had to be reinforced to secure stability. Second, the specification of pipes, especially rafter, could be classified as two cases. One had a structural stability at a safe wind velocity of $35m{\cdot}s^{-1}$ and a safe snow-depth of 40 cm for which stability the rafter had to be ${\Phi}31.8{\times}1.5t@600$, and the other had a stability at $30m{\cdot}s^{-1}-35cm$ at the specification of rafter ${\Phi}25.4{\times}1.5t@600$. Finally, eaves height had a significant effect on safe wind velocity. But it had little influence on safe snow-depth. The results showed that the specification of side-wall pipes had to be reinforced for the safe side velocity accord-ing to the increment of eaves height and similarly the specification of fore-end post far the safe fore-end velocity.

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.

Numerical Investigation of Urea Freezing and Melting Characteristics Using Coolant Heater (냉각수 순환 가열 방식을 이용한 요소수의 동결 및 해동 특성에 관한 수치적 연구)

  • Lee, Seung Yeop;Kim, Nam Il;Park, Yun Beom;Kim, Man Young
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.37 no.8
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    • pp.717-724
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    • 2013
  • Urea-SCR technology is known as one of the powerful NOx reduction systems for vehicles as well as stationary applications. For its consistent and reliable operation in vehicle applications, however, the freezing and melting of the urea solution in cold environments have to be resolved. In this study, therefore, a numerical study of three-dimensional unsteady problems was analyzed to understand the urea freezing and heating phenomena and heat transfer characteristics in terms of urea liquid volume fraction, temperature profiles, and phase change behavior in urea solutions with time by using the commercial software Fluent 6.3. As a result, it was found that the freezing phenomenon proceeds with a phase change from the tank wall to the center, whereas the melting phenomenon occurs faster in the upper part of the storage tank by natural convection and in the adjacent part of the coolant pipe than in other parts. Furthermore, approximately 190 s were required to obtain 1L of urea solution using a 4-coiled coolant heater under conditions of $70^{\circ}C$ and 200 L/h.

A study on the Need for Introducing the Information and Communication Facilities Maintenance Mandatory System: In view of Apartment House Environment) (정보통신설비의 유지관리 의무화제도 도입 필요성에 관한 연구(공동주택환경을 중심으로))

  • Lim, Sang-Chool;Kim, Sun-Hyung
    • Journal of The Institute of Information and Telecommunication Facilities Engineering
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    • v.6 no.3
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    • pp.15-24
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    • 2007
  • According to an apartment house environment and the service provide method of major telecom operators, is providing optic-LAN service with installing the equipments of optical office center and optic distribution at MDF(Main Distribution Frame) and under-ground of apartment. therefore the distribute is deepening between service providers because of space securement to install equipments and spare pipe securement to reinstall UTP cable. These were reasons that operators leaned to subscriber collection and neglected to maintenance, in addition, insist the facilities invested by each operators is his own assets for all that in-plant of apartment house is private land. So, would not being touched by others. Accordingly, this study will search it through the field current condition examine that service's types and methods which various telecom operators and broadcast operators are providing, the current conditions of being maintained, the problems of being happened. etc. and would like to improve that the users could use the services safely by making the information & communication facilities maintenance mandatory under the regular size of apartment house circumstances through the analysis of various laws relations which are managed information & communication construction work law, telecommunication basis law, home network. etc. technical standards by the Ministry of Information and Communication and are managed housing law, construction law, the regulation related to house construct standards. etc. by the Ministry of Construction and Transportation.

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The Primary Structure Controlled Mineralization in Weolseong Diatreme, Southern Korea (월성(月城) 다이아튜림의 층준(層準)에 따른 광화(鑛化) 현상(現狀))

  • Park, Ki-Hwa;Oh, Mihn-Soo
    • Economic and Environmental Geology
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    • v.20 no.1
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    • pp.19-34
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    • 1987
  • The Nokdong As-Zn deposit, located 28 km south of Kyeongju City, Southern Korea, has been investigated by a deep drilling programme. The mineralized zone is roughly 290m long and 180m wide at surface and is hosted in a pipe diatreme infilled with poor to well bedded felsic volcaniclastics. The diatreme was formed by explosive volcanic activity, of probably early Tertiary age, subsequent hydrothermal alteration and mineralization took place concurrently within stratigraphic layers in diatreme. Coarse volcaniclastics in the center part of the diatreme, together with complex systems of fracturing, acted as pathways for late hydrothermal fluids which caused alteration of volcanic material to sericite, chlorite and carbonate and precipitated ore minerals, quartz and calcite in the voids. Porosity and permeability were key factors in determining which portions of the layered diatreme were mineralized. The lower part of certain layers retained a relatively high porosity and were extensively mineralized. Metallic mineralization, consisting mostly of pyirte, sphalerite and arsenopyrite, is found as disseminations, tuff-breccia filling and veins.

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