• Title/Summary/Keyword: Water Flow Test

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Critical Heat Flux and Flow Pattern for Water Flow in Annular Geometry

  • Park, Jae-Wook;Baek, Won-Pil;Chang, Soon-Heung
    • Proceedings of the Korean Nuclear Society Conference
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    • 1996.11a
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    • pp.224-229
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    • 1996
  • An experimental study on critical heat flux (CHF) and two-phase flow visualization has been performed for water flow in internally-heated, vertical, concentric annuli under near atmospheric pressure. Tests have been done under stable forced- circulation, upward and downward flow conditions with three test sections of relatively large gap widths (heated length = 0.6 m. inner diameter = 19 mm, outer diameter = 29, 35 and 51 mm). The outer wall of the test section was made up of the transparent Pyrex tube to allow the observation of flow patterns near the CHF occurrence. The CHF mechanism was changed in the order of flooding, chum-to-annular flow transition, and local dryout under a large bubble in churn flow as the flow rate was increased from zero to higher values. Observed parametric trends are consistent with the previous understanding except that the CHF for downward flow is considerably lower than that for upward flow.

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An Experimental Study on the Characteristic of Thermal Performance according to Feed Water Conditions to of Vacuum Membrane Distillation Module using PVDF Hollow Fiber (PVDF 중공사막을 이용한 진공 막 증류 모듈의 공급수 조건에 따른 열성능 특성에 관한 실험적 연구)

  • Joo, Hongjin;Kwak, Heeyoul
    • Journal of Korean Society of Water and Wastewater
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    • v.31 no.4
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    • pp.339-346
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    • 2017
  • In this study, thermal performance test of VMD module was performed, prior to the construction of the demonstration plant using the vacuum membrane distillation (VMD) module of the capacity of $400m^3/day$ and to the commercialization of the VMD module. For the thermal performance test, the experimental equipment of capacity of $2m^3/day$ was constructed. The permeate flux test and thermal performance test according to feed water conditions such as temperature and flow rate were conducted. The VMD module used in the study was manufactured by ECONITY Co., LTD with PVDF hollow fiber membrane. As a result, the Performance Ratio (PR) of the VMD module showed the maximum value of 0.904 under the condition of feed water temperature of $75^{\circ}C$ and flow rate of $8m^3/h$. PR value of the VMD module using PVDF hollow fiber membrane showed linearly increasing relationship with feed water temperature and flow rate. Also, The permeate flux of the VMD module was analyzed to have maximum value of 18.25 LMH and the salt rejection was 99.99%.

Hydraulic Residence Time in a Prototype Free Water Surface Constructed Wetland

  • Lee, Kyung-Do;Kwun, Soon-Kuk;Kim, Seong-Bae;Cho, Young-Hyun;Kim, Jin-Ho
    • Korean Journal of Environmental Agriculture
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    • v.24 no.1
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    • pp.6-11
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    • 2005
  • A prototype surface flow constructed wetland was built in the upstream area of reclaimed tidal lands to improve the water quality of Lake Sihwa by treating severely polluted stream water. In this study, a tracer test using rhodamine-WT was performed to investigate the flow characteristics and to quantify the observed hydraulic residence time (HRT) for a high-lying cell in the Banwol wetland of the Sihwa constructed wetland. The tracer test indicated that even if flow was mainly observed in the open water area of the Banwol wetland, water flowed continuously in the vegetative area and there was no dead zone. The calculated HRT (51.3 hrs), calculated by dividing the wetland volume by the wetland inflow, exceeded the observed HRT (38.7 hrs), since the short-circuiting of flux resulting from irregular topography and vegetation was not reflected in the calculated HRT. The exit tracer concentration curves were reproduced well by both the plug flow with dispersion and tanks-in-series models, indicating that the performance of the Banwol wetland can be estimated accurately using these models.

Evaluation of Hydraulic Characteristics Influenced by Different Deflector Baffles in the Sedimentation Basin with Inclined Plate Settler (경사판 침전지에서 저류벽의 설치위치에 따른 수리학적 특성의 평가)

  • Yu, Myong-Jin;Kim, Hyun-Chul;Ryu, Seong-Ho
    • Journal of Korean Society on Water Environment
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    • v.21 no.1
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    • pp.40-45
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    • 2005
  • Sedimentation is one of the most common and important units in conventional water treatment plant. Structure such as various baffle walls and inclined plate settler may be obstacles to the horizontal flow when it is poorly designed. Therefore, the effects of these structures on characteristics of hydraulic flow must be evaluated to improve the settling efficiency of the floc. The hydraulic characteristic of the two sedimentations at Y water treatment plant (YWTP), which have different deflector baffles inside the settling basin, were investigated by tracer (fluoride) test. The inclined plate settler installed inside settling basin caused an undesirable impact on horizontal flow and produced dead zone. Solid baffle wall under the plate settler could help to minimize the formation of density currents and flow short circuiting. NaF used as a tracer was recovered more than 90% at investigated all basins. Morill index ($t_{90}/t_{10}$), Modal index ($t_p/T-HRT$) and short-circuiting index ($[M-HRT-t_p]/M-HRT$) were determined from tracer test results performed at YWTP. Those indices ranged 2.95~3.02, 0.40~0.53 and 0.32~0.46, respectively.

A Nonparametric Trend Tests Using TMDL Data in the Nakdong River (낙동강 수계의 수질오염총량 자료를 이용한 비모수적 수질추세 분석)

  • Kim, Mi-Ah;Lee, Soyoung;Mun, Hyunsaing;Cho, Hang-Soo;Lee, Jae-kwan;Kim, Kyunghyun
    • Journal of Korean Society on Water Environment
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    • v.33 no.1
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    • pp.40-50
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    • 2017
  • We were interested in the long-term temporal and spatial variability trends of water quality. Trend tests such as the Seasonal and Regional Kendall tests and LOWESS (LOcally WEighted Scatter plot Smoother) have been recommended as outstanding tools for trend detection. In this study, we conducted four types of nonparametric trend tests (Seasonal and Regional Kendall tests, LOWESS, and flow-adjusted Seasonal Kendall). We aimed to identify water quality trends using the monthly data for five variables (BOD, COD, TN, TP, and flow) collected from 24 sites in the Nakdong River from August 2004 to December 2013. According to the Regional Kendall test, BOD, COD, and TN increased but TP decreased trend. The Seasonal Kendall test showed that BOD, TN, and TP remained constant at 62.5-83.3% of the sites. COD remained constant at 58.3% of the sites. LOWESS showed that TP gradually increased between 2007 and 2008, then decreased slowly at the Gumi, Geumhogang6, Daeam-1 and Milyanggang3 sites. BOD increased slightly between 2008 and 2009, and then decreased slowly at the Namgang4-1 site. Lastly, a flow-adjusted Seasonal Kendall test was conducted. There were different results between Seasonal Kendall and flow-adjusted Seasonal Kendall tests at 11 of the 24 sites. According to the results from six of the eleven sites, BOD increased at one site, showed no trends at three sited, and decreased at two sites. Each of COD, TN increased at two, one site. but TP decreased at two sites.

Depressurized Circulating Water Channel Design Using CFD (수치 해석을 이용한 감압 회류 수조 설계)

  • 부경태;조희상;신수철
    • Journal of the Society of Naval Architects of Korea
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    • v.40 no.4
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    • pp.22-29
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    • 2003
  • New high-speed depressurized circulating water channel was designed by using the CFD code. Flow in the channel has free surface and pressure in the test section can be depressed. In this study, Flow separation and bubble occurrence were considered in designing the contraction nozzle shape for better flow uniformity Tn the test section. To supplement velocity defect due to the free surface, nozzle injection system more effective in high-speed flow was installed instead of drum system. Necessary power and injection techniques were proposed. And guide vane arrangement was analyzed to reduce the flow resistance and keep quiet free surface from ´surging´. Wave absorber was devised to reduce the wave resistance and to prevent the entrainment of air to the diffuser.

Efficiency Analysis for Water Turbine Generator of Agricultural Reservoir (농업용 보의 수차 발전기 효율 분석)

  • Kim, Jong-Gyeum
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.62 no.9
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    • pp.1223-1227
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    • 2013
  • If the factory test efficiency and field operation efficiency of water turbine are different from each other, issues for efficiency warranty can be raised. So, This paper shows the result for comparative analysis of field operating efficiency vs plant testing efficiency of the water turbine generator installed in agricultural reservoir. The efficiency of the induction generator is analyzed by the change of rotational speed with the parameter obtained by test, the efficiency of water turbine is calculated by the change of head with the design flow. Efficiency deviation of induction generator is lower but the variation of developed power is pretty high near the rated speed and the efficiency variation of water turbine is high by the fluctuation of head for constant flow. It was found that factory test efficiency and total efficiency of water turbine generator calculated according to the rotational speed are very close.

A study on improvement of painting quality through a de-painting phenomenon of KUH-1 tail blade (한국형 기동헬기 꼬리 날개 디페인팅 현상을 통한 도장 품질 향상에 관한 연구)

  • Chang, In-Ki;Kim, Young-Jin;Seo, Hyun-Soo;Jeon, Boo-Il
    • Journal of Korean Society for Quality Management
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    • v.42 no.3
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    • pp.325-338
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    • 2014
  • Purpose: The purpose of this study was to explain de-painting phenomenon of KUH-1 tail blade and to propose useful solution of it by test. The proposed solution was evaluated by real flight, and then it applied to mass product to improve the paint qual ity of KUH-1 tail blade. Methods: This study investigated an adhesive ability of primer following surface sanding condition. The cross cut and scratch test were conducted to evaluate the adhesive strength. And the water flow test was designed to simulate a real flight condition under rain. Through water flow test, an optimal condition of tail blade to prevent a de-painting phenomenon was deduced. Finally, the improvement method was evaluated by real flight under rain. Results: The results of this study are as follows; The sequential polishing was most excellent method in primer painting quality. The results of test including cross cut, scratch and water flow showed that MIL-DTL-53039 paint with epoxy primer has excellent adhesive ability. To proof the effect of improvement, a real flight during a rain condition was conducted. Finally, the comparison between original and improved configuration was conducted. Conclusion: The painting quality of KUH-1 tail blade was improved through deriving an optimal painting condition. In detail, a condition of optimal sanding and a sort of primer and paint was showed. Finally, the reliability of tail blade was guaranteed through improving the quality of painting.

Air-Water Two-Phase Flow Test Facility of a Single Stage Closed-type Centrifugal Pump (단단 밀폐형 원심펌프의 기액이상류 성능시험 설비)

  • Kim, S. Y.;Lee, S. L.;Kim, Y. T.;Kim, S. D.;Lee, Y. S.;Lee, Y. H.
    • 유체기계공업학회:학술대회논문집
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    • 2004.12a
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    • pp.49-53
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    • 2004
  • LabVIEW is mostly preferred to use in experiment, measurement and control as one of the useful thing in America and Europe. So, We tried performance experiment of a single-stage closed-type centrifugal pump by using the LabVIEW. The pump rpm and the shaft torque are measured by rpm sensor and torque sensor The test pump's maximum rpm, head, kW are 1,750, 13m, and 1.5kW, respectively The casing is made up with transparency acrylic for confirmation the flow patterns. We installed experimental equipment for air water two phase flow. This paper tries to analyze the single-phase flow characteristics through this air water two phase flow experimental apparatus. The performance results of a single-stage closed-type centrifugal pump satisfied reappearance and coincide well with head and coefficients according to the change of rpm.

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MEASUREMENT OF THE SINGLE AND TWO PHASE FLOW USING A NEWLY DEVELOPED AVERAGE BIDIRECTIONAL FLOW TUBE

  • Yun, Byong-Jo;Euh, Dong-Jin;Kang, Kyunc-Ho;Song, Chul-Hwa;Baek, Won-Pil
    • Nuclear Engineering and Technology
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    • v.37 no.6
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    • pp.595-604
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    • 2005
  • A new instrument, an average BDFT (Birectional Flow Tube), was proposed to measure the flow rate in single and two phase flows. Its working principle is similar to that of the Pilot tube, wherein the dynamic pressure is measured. In an average BDFT, the pressure measured at the front of the flow tube is equal to the total pressure, while that measured at the rear tube is slightly less than the static pressure of the flow field due to the suction effect downstream. The proposed instrument was tested in air/water vertical and horizontal test sections with an inner diameter of 0.08m. The tests were performed primarily in single phase water and air flow conditions to obtain the amplification factor(k) of the flow tube in the vertical and horizontal test sections. Tests were also performed in air/water vertical two phase flow conditions in which the flow regimes were bubbly, slug, and churn turbulent flows. In order to calculate the phasic mass flow rates from the measured differential pressure, the Chexal drift-flux correlation and a momentum exchange factor between the two phases were introduced. The test results show that the proposed instrument with a combination of the measured void fraction, Chexal drift-flux correlation, and Bosio & Malnes' momentum exchange model could predict the phasic mass flow rates within a $15\%$ error. A new momentum exchange model was also proposed from the present data and its implementation provides a $5\%$ improvement to the measured mass flow rate when compared to that with the Bosio & Malnes' model.