• Title/Summary/Keyword: Inflow rate

Search Result 520, Processing Time 0.024 seconds

A Study on Usage of Results from Batch Reactor for Design of Aerobic Digestion (호기성 소화조 설계시 회분식 반응조에서 획득된 결과의 이용방안에 관한 연구)

  • Choung, Youn-Kyoo;Ko, Kwang-Baik;Park, Joon-hong
    • Journal of Korean Society of Water and Wastewater
    • /
    • v.8 no.3
    • /
    • pp.1-8
    • /
    • 1994
  • In the general process of design for aerobic digestion, the design for field plant of which inflow pattern is continuous inflow is performed using the results from lab scale batch reactor. However, the recent researchers reported that the general designs were performed as over-estimated, Therefore, in this study, laboratory batch experiments were carried out at $20^{\circ}C$ and pH 7.5 on the aerobic digestion of waste activated sludge at different solid levels. This treatise could consider the negligence about effective digestion periods the usage of VSS as solid concentration, and the effect of initial solid concentration of solid degration rate coefficient($k_d$) as reasons of the overestimated design, and showed the scheme of how to design for aerobic digestion from batch experiment.

  • PDF

A Study on the Prediction of Performance and Simulation in a Radial inflow-Turbine for Exhaust Gas Turbochargers (과급기 구동용 반경류 배기터빈의 수치해석과 성능예측)

  • Jeong, Hyo-Min;Koh, Dae-Kwon
    • Journal of the Korean Society of Fisheries and Ocean Technology
    • /
    • v.29 no.3
    • /
    • pp.220-228
    • /
    • 1993
  • This paper presents a description and evaluation of a detailed mathematical simulation for the steady and unsteady flow in a radial inflow-turbine which is most frequently used, at present, for exhaust gas turbochargers of internal combustion engines. As a method of computation, the two-step differential Lax-Wendroff method and the characteristic method were used. The turbine characteristics, the mass flow rate, the power output and fluid movements at the turbine scroll inlet were compared with the experiment data. The results of the simulation were in good agreement with experimental values under both steady and unsteady flow conditions.

  • PDF

Operational Strategy of Anaerobic Digesters Considering Energy Balance (에너지수지를 고려한 혐기성소화시설의 운영방안)

  • Hong, Seong-Gu;Kwun, Soon-Kuk
    • Journal of The Korean Society of Agricultural Engineers
    • /
    • v.50 no.4
    • /
    • pp.59-66
    • /
    • 2008
  • Anaerobic digestion system is getting more attractive in that it produces biogas in the process of organic waste stabilization. Net energy production is important when biogas production is concerned. In this study, net energy production was evaluated with respect to biogas production and heat losses in a hypothetical digester. Under the condition of digester operation with slurry inflow of 5% of TS, additional fuel is required to maintain digester temperature during the winder season. Substrate therefore, needs to have higher VS contents through co-digestion of silage or food waste that has greater values of methane production rate. Heating input slurry is important in cold season, which covers over 80% of heating requirement. Heat recovery from digestate is valuable to reduce the use of biogas for heating. It seems desirable to minimize slurry inflow when temperature is very low. Psychrophilic digestion may be a feasible option for reducing heating requirement.

Seasonal Changes of Environmental Factors and Primary Productivity in the Jido Pond Ecosystem (지도못 生態系에 있어서의 1次 生産性과 環境要因의 계절적 變化)

  • Lyu, Seung-Won;Song, Seung-Dal
    • The Korean Journal of Ecology
    • /
    • v.7 no.2
    • /
    • pp.61-66
    • /
    • 1983
  • Seasonal changes of aquatic environmental factors, phytoplankton biomass and primary productivity were investigated in the Jido pond (a phytoplankton proliferating pond) from August 1982 to October 1983. Secchi disc transparency, pH, alkalinity and inorganic nitrogen concentration ranged 24~105cm, 7.5~10.6, 50~175mgCaCO3/l 0.1~4.0mgN/l, respectively. The minimum values of transparency, alkalinity and inorganic nitrogen concentration and the maximum value of pH were obtained during the phytoplankton proliferating season. The phytoplankton biomass changed in the range of 51~1146mgchl/m3 with considerable fluctuations but maintained fairly constant in winter. Themaximum and minimum rates of monthly carbon inflow (net primary production) of the phytoplankton community attained 1190gc/m2 in August 1982 and 68g/m2 in February 1983, respectively. The annual rates of inflow and outflow from August 1982 to July 1983 were 7.384 and 7.396kgc/m2, respectively. Turnover rate of phytoplankton carbon and efficiency of radiation of the phytoplankton community varied in the ranges of 60~130%/day (annual mean, 90%/day) and 0.9~11.2% (annual mean, 6.3%), respectively.

  • PDF

Re-evaluation of Soyang Dam inflow based on modifying a simple water balance method considering evaporation (증발량을 고려한 단순 물수지 방정식 개선을 통한 소양강댐 유입량의 재평가)

  • Yoo, Jiyoung;Lee, Dong Jin;Yoo, Do-Guen;Kim, Tae-Woong
    • Journal of Korea Water Resources Association
    • /
    • v.55 no.6
    • /
    • pp.461-469
    • /
    • 2022
  • It is very important to ensure the reliability of dam inflow data, which is critical in planning and managing the supply and demand of water resources in a basin. However, the simple water balance model sometimes results in negative inflows and does not consider the actual inflow characteristics. In this study, to address these issues, the existing water balance formula was modified by considering evaporation which is available for calculation among other outflows. The modified water balance formula was applied to the Soyang Dam. The results showed that the rate of negative inflows decreased in the re-evaluated dam inflow data and it was possible to secure consistency for the total inflow volume. In addition, investigating the water availability in the Soyang Dam watershed based on the water balance concept considering evaporation, it was found that direct water use in the human aspect was about 60%, and the indirect water use in the natural aspect was about 40%. In drought years, it was also confirmed that the proportion of indirect use of water resources increased.

Study of Surges in a Large-Diameter Subteranean Diversion Channel with Multiple Surge Tanks (대심도 지하관로 배수 시스템의 서어징 현상에 관한 연구)

  • Jeong, Gwang-Geun;Yeo, Un-Sik;An, Tae-Jin
    • Journal of Korea Water Resources Association
    • /
    • v.31 no.6
    • /
    • pp.757-768
    • /
    • 1998
  • rate of outflow is equated to the total rate of flow, both the state equation and its linearized equation yield almost identical oscillations of water levels. This shows that effects of pipe resistance on the surges are small, and justifies a free oscillation analysis. Free oscillation equation has six eigen modes of different periods, including a rigid mode which is existed when the pumped rate of outflow differs from the total rate of inflow. The six modes constitute a variety of surges dependent on different inflow and outflow conditions. Presence of the rigid mode needs sophisticated pump operations adjusted to real flood inflows.

  • PDF

Study of Hydraulic Characteristics with the Shape of the Intake of an Underground Inflow Facility using Hydraulic Experiments (수리실험을 이용한 지하유입시설 유입구 형상에 따른 수리학적 특성 분석)

  • Seong, Ho Je;Park, In Hwan;Rhee, Dong Sop
    • Journal of the Korean Society of Safety
    • /
    • v.33 no.4
    • /
    • pp.119-126
    • /
    • 2018
  • In recent years, as flood damage caused by heavy rains increased, the great-depth tunnel using urban underground space is emerging as a countermeasure of urban inundation. The great-depth tunnel is used to reduce urban inundation by using the underground space. The drainage efficiency of great-depth tunnel depends on the intake design, which leads to increase discharge into the underground space. The spiral intake and the tangential intake are commonly used for the inlet facility. The spiral intake creates a vortex flow along the drop shaft and reduces an energy of the flow by the wall friction. In the tangential intake, flow simply falls down into the drop shaft, and the design is simple to construct compared to the spiral intake. In the case of the spiral intake, the water level at the drop shaft entrance is risen due to the chocking induced by the flowrate increase. The drainage efficiency of the tangential intake decreases because the flow is not sufficiently accelerated under low flow conditions. Therefore, to compensate disadvantages of the previously suggested intake design, the multi-stage intake was developed which can stably withdraw water even under a low flow rate below the design flow rate. The hydraulic characteristics in the multi-stage intake were analyzed by changing the flow rate to compare the drainage performance according to the intake design. From the measurements, the drainage efficiency was improved in both the low and high flow rate conditions when the multi-stage inlet was employed.

Seasonal Variation of Pollutant load flowing into Yeong-Il bay (영일만 유입오염부하량의 계절 변동에 관한 연구)

  • Yoon, Han-Sam;Lee, In-Cheol;Ryu, Cheong-Ro;Park, Jong-Hwa
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
    • /
    • 2002.10a
    • /
    • pp.100-107
    • /
    • 2002
  • This study investigates the seasonal variation and spatial distribution characteristics of pollutant load, as executing the quantity valuation of pollutant load inflowing into Yeong-Il bay from on-land including the Hyeong-san river. Annual total pollutant generating rate from Yeong-Il bay region are 202ton to BOD, 620ton to SS, 42ton to T-N, 16ton to T-P respectively, if expressly point out, pollutant generating rate from the Hyeong-san river is the greatest, which BOD ratio is 78.2%, SS 88.5%, T-N 62.5%, T-P 73.1%. As calculating Tank model with input value of daily precipitation and evaporation of 2001 year in drainage basin of the Hyeong-san river, Estimated result of the annual total river discharge effluencing from this river is $830{\times}106m^3$. As result to estimating annual total effluence rate outflowing at the rivers from each drainage basins, annual total inflow pollutant rate are BOD 10,633ton, SS 19,302ton, T-N 15,369ton, T-P 305ton. The III basin which is population congestion region of the Pohang-city drain away a good many pollutant load than the V basin including the Neang-Chun with wide drainage area. Especially, a great many T-N than T-P inflow into Yeong-Il bay. The accumulation of pollutant load effluenced from on-land will happen on at the inner coast region of Yeong-Il bay, finally we would make a prediction that the water quality will take a bad turn.

  • PDF

Effect of Influent Gas on Mechanical Acceleration Durability Test of PEMFC Polymer Membrane (PEMFC 고분자막의 기계적 가속 내구 평가 과정에서 유입 가스의 영향)

  • Oh, Sohyeong;Hwang, Byungchan;Jung, Sunggi;Jeong, Jihong;Park, Kwonpil
    • Korean Chemical Engineering Research
    • /
    • v.60 no.3
    • /
    • pp.321-326
    • /
    • 2022
  • As the thickness of the polymer membrane of PEMFC(Proton Exchange Membrane Fuel Cells) is getting thinner for PEMFC performance and price reduction, research on improving durability has become more important. In the durability evaluation of membranes, the mechanical durability evaluation time is more than twice that of the chemical durability evaluation time, so it is necessary to select the durability evaluation conditions well. In this study, we tried to check how much the mechanical durability evaluation time changes when there is a difference in the inflow gas type and flow rate in the mechanical durability evaluation protocol (Wet/Dry). When nitrogen was used at a flow rate of 2,000 mL/min, the evaluation time increased by 1.25 times compared to when air was used. An increase in the degradation rate of the electrode Pt was the main factor when air was used. When the flow rate was reduced to 800 mL/min, the air and nitrogen evaluation times increased by 1.5 times and 1.2 times, respectively.

Study on Rate Dependent Fracture Behavior of Structures; Application to Brittle Materials Using Molecular Dynamics (구조물의 속도 의존적 파괴 특성에 대한 연구; 입자동역학을 이용한 취성재료에의 적용)

  • Kim, Kunhwi;Lim, Jihoon;Llim, Yun Mook
    • KSCE Journal of Civil and Environmental Engineering Research
    • /
    • v.28 no.4A
    • /
    • pp.529-536
    • /
    • 2008
  • The failure behavior of structures is changed under different loading rates, which might arise from the rate dependency of materials. This phenomenon has been focused in the engineering fields. However, the failure mechanism is not fully understood yet, so that it is hard to be implemented in numerical simulations. In this study, the numerical experiments to a brittle material are simulated by the Molecular Dynamics (MD) for understanding the rate dependent failure behavior. The material specimen with a notch is modeled for the compact tension test simulation. Lennard-Jones potential is used to describe the properties of a brittle material. Several dynamic failure features under 6 different loading rates are achieved from the numerical experiments, where remarkable characteristics such as crack roughness, crack recession/arrest, and crack branching are observed during the crack propagation. These observations are interpreted by the energy inflow-consumption rates. This study will provides insight about the dynamic failure mechanism under different loading rates. In addition, the applicability of the MD to the macroscopic mechanics is estimated by simulating the previous experimental research.