2 상 유동 및 물질전달 특성에 미치는 오리피스 노즐형상과 소요동력의 영향

양희천(Hei Cheon Yang) 대한기계학회 2016 大韓機械學會論文集B Vol.40 No.4

호기성 수처리 과정의 폭기에 소요되는 에너지의 이용효율을 높이기 위해서는 물질전달 특성뿐만 아니라 소요동력에 대한 연구가 필요하다. 본 논문은 수직 2 상 유동 및 물질전달 특성에 미치는 오리피스 노즐형상과 소요동력의 영향에 대한 실험적 연구를 목적으로 한다. 측정 변수들을 이용하여 유량비, 소요동력, 물질전달 계수 그리고 물질전달 효율을 산출하였다. 소요동력이 커지면 물질전달 계수는 증가하는 반면에 유량비와 물질전달 효율은 감소하였다. 무차원 면적비가 작은 오리피스 노즐의 유량비, 물질전달 계수 및 효율이 높게 나타났다. 물질전달 특성에 미치는 유량비, 소요동력 그리고 프라우드 수의영향을 평가하기 위한 실험식을 제시하였다. It is necessary to investigate the input power as well as the mass transfer characteristics of the aeration process in order to improve the energy efficiency of an aerobic water treatment. The objective of this study is to experimentally investigate the effect of orifice nozzle design and input power on the flow and mass transfer characteristics of a vertical two-phase flow. The mass ratio, input power, volumetric mass transfer coefficient, and mass transfer efficiency were calculated using the measured data. It was found that as the input power increases the volumetric mass transfer coefficient increases, while the mass ratio and mass transfer efficiency decrease. The mass ratio, volumetric mass transfer coefficient, and mass transfer efficiency were higher for the orifice configuration with a smaller orifice nozzle area ratio. An empirical correlation was proposed to estimate the effect of mass ratio, input power, and Froude number on the volumetric mass transfer coefficient.

바나듐레독스흐름전지 전해질 유량에 따른 성능변화

이건주,김선회 한국수소및신에너지학회 2015 한국수소 및 신에너지학회논문집 Vol.26 No.4

The electrolyte flow rates of vanadium redox flow battery play very important role in terms of ion transfer to electrolyte, kinetics and pump efficiency in system. In this paper a vanadium redox flow battery single cell was tested to suggest the optimization criteria of electrolyte flow rates on the efficiencies. The compared electrolyte circulation flow rates in this experimental work were 15, 30 and 45 mL/min. The charge/discharge characteristics of the flow rate of 30 mL/min was the best out of all flow rates in terms of charging and discharging time. The current efficiencies, voltage efficiencies and energy efficiencies at the flow rate of 30 mL/min were the best. The IR losses obtained at thd current density of 40 mA/cm 2 , at the flow rates of 15, 30 and 45 mL/min were 0.085 V, 0.042 V and 0.115 V, respectively. The charge efficiencies at the current density of 40 mA/cm 2 were 96.42%, 96.45% and 96.29% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. The voltge efficiencies at the current density of 40 mA/cm 2 were 77.34%, 80.62% and 76.10% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively. Finally, the energy efficiencies at the current density of 40 mA/cm 2 were 74.57%, 77.76% and 73.27% for the electrolyte flow rates of 15, 30 and 45 mL/min, respectively.The optimum flow rates of electrolytes were 20 mL/min in most of operating variables of vanadium redox flow battery.

수직 오리피스 이젝터의 혼합유동 및 산소전달 특성

김동준(Dong Jun Kim),박상규(Sang Kyoo Park),양희천(Hei Cheon Yang) 대한기계학회 2015 大韓機械學會論文集B Vol.39 No.1

본 논문은 수직 오리피스 이젝터의 혼합유동 및 산소전달 특성에 대한 실험적 연구를 목적으로 한다. 실험장치는 전동 모터-펌프, 오리피스 이젝터, 순환 수조, 공기압축기, 고속 카메라 시스템 그리고 제어 및 측정기기로 구성하였다. 측정된 구동유체 및 유입공기의 유량을 이용하여 유량비를 도출하였다. 이적터에서 분출된 혼합유동의 가시화를 통해 정성적 거동을 고찰하였으며, 용존산소 농도를 측정하여 총괄 산소전달계수를 도출하였다. 구동유체의 유량이 일정하고 압축기의 공기압이 높아지면 유량비와 산소전달계수는 증가하며, 압축기의 공기압이 일정하고 구동유체의 유량이 증가하면 유량비는 감소하지만 산소전달계수는 증가하였다. 기포의 크기에 따른 체류시간 및 확산도와 수직 혼합유동의 도달거리는 2 상의 접촉면적과 시간에 크게 영향을 미치기 때문에 산소전달율의 중요한 변수임을 유추할 수 있다. The objective of this study is to experimentally investigate the mixed flow behaviors and oxygen transfer characteristics of a vertical orifice ejector. The experimental apparatus consisted of an electric motor-pump, an orifice ejector, a circulation water tank, an air compressor, a high speed camera unit and control or measurement accessories. The mass ratio was calculated using the measured primary flow rate and suction air flow rate with experimental parameters. The visualization images of vertically injected mixed jet issuing from the orifice ejector were qualitatively analyzed. The volumetric oxygen transfer coefficient was calculated using the measured dissolved oxygen concentration. At a constant primary flow rate, the mass ratio and oxygen transfer coefficient increase with the air pressure of compressor. At a constant air pressure of the compressor, the mass ratio decreases and the oxygen transfer coefficient increases as the primary flow rate increases. The residence time and dispersion of fine air bubbles and the penetration of mixed flow were found to be important parameters for the oxygen transfer rate owing to the contact area and time of two phases.

R22를 적용한 전자팽창밸브의냉매유량 특성 및 유량예측 모델링

박차식,이선일,김용찬,이영수 대한설비공학회 2006 설비공학 논문집 Vol.18 No.11

The objective of this study are to analyze the flow characteristics of R22 flowing through EEVs and to develop an empirical correlation to predict the refrigerant flow rate. The mass flow rates of EEVs with different geometries were measured at various condensing temperatures, subcoolings, and EEV openings. Based on the experimental data, an empirical correlation for mass flow predictions in EEVs was developed by modifying the orifice equation. The correlation showed good agreement with the measured data for R22 with average and standard deviations of 1.4% and 6.1%, respectively. Approximately 90% of the measured data were within ±10% of the predictions.

흡기유량에 따른 디젤엔진에서의 배출가스 특성에 대한 연구

김형준 ( Hyung Jun Kim ),박용희 ( Yong Hee Park ),엄명도 ( Myoung Do Eom ),고종민 ( Jong Min Ko ),황진우 ( Jin Woo Hwang ),이상현 ( Sang Hyun Lee ),길지훈 ( Ji Hoon Keel ),김정수 ( Jeong Soo Kim ) 한국분무공학회 2013 한국액체미립화학회지 Vol.18 No.1

The investigation was conducted to analyze the exhaust emission characteristics in diesel engine according to intake air mass flow. In this study, the test diese engine with a 5,899 cubic centimeter displacement and power of the 260 ps was used to analyze the emission characteristics according to the intake air mass flow. In addition, the test modes were applied by the ND-13 and ETC mode. In order to analyze the emission characteristics, the engine dynamometer with 440 K W and emission gas analyzer (AMA-4000) were utilized. From the experimental results, it is revealed that the Nox and HC emis-sions in the intake air mass flow of large amount have high levels compared to those in the intake air mass flow of large amount have high levels compared to those in the intake air mass flow of small amount in the ND-13 mode . However , the PM emission was shown the opposite trend in the NOx and HC emission due to the trade-off relation between the NOx and PM.

다공 오리피스를 이용한 액체산소 유량측정

임하영(Hayoung Lim),이지성(Jisung Lee),김정한(Junghan Kim),노용오(Yongoh Noh) 한국추진공학회 2017 한국추진공학회 학술대회논문집 Vol.2017 No.5

액체산소의 유량을 측정하기 위해 두 가지 형태의 다공성 오리피스 미터를 제작하여 물을 이용하여 Cd 를 측정하였다. 다공 오리피스 미터와 코리올리 미터를 직렬로 연결하고 액체산소를 흘려보내는 유동시험을 수행하여 물을 이용하여 구한 Cd 를 이용하여 질량유량을 산출하였다. 코리올리 미터를 기준으로 할 때 A 형(1/2")의 경우 0.4%, B 형(3/4")의 경우 0.8% 이하의 오차를 확인하였다. To measure the flow rate of the liquid oxygen, two types of multi-hole orifice meter were prepared. The Cd of the orifice meter was determined by the flow test using water. After performing the liquid oxygen flow test for orifice meter and Coriolis meter, the mass flow rate was calculated using the Cd. The error of the mass flow rate compare to Coriolis meter, A-type(1/2") was below than 0.4%, B-type(3/4") was below than 0.8%.

열식 유량계의 운전온도 범위 확장을 위한 센서부 열전달 계수에 관한 연구

강병우(Byung-woo Kang),양승철(Seung-chul Yang),성낙원(Nak-won Sung),이도형(Do-hyung Lee) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-

In order to measure gas flux, there are some techniques based on volume flux and mass flux. The mass flux measurement is more favored to measure correctly gas flux under the extremely - high thermal or extremely - low pressure conditions. The thermal mass flow-meter is the representative technique to measure mass flux. In designing the flow-meter, it is important to calibrate convectional thermal coefficient affected by flow velocities around sensor and thermal changes. To analyze quantitatively the convectional mechanism around cylinders in high thermal external flow , experiments are conducted through installing 40m3/min blower at 100 mm duct for high thermal gases and heater able to bring ambient gas up to 200 ℃. By using control valves at the end point of duct, we controlled fluid velocities. By installing Pt 100 sensor to the heater, fluid temperature is controlled. In this experiment, convectional coefficients around cylinders are proportional to velocity to the power of 0.45 . A and B in the correlation equation coefficients behaved independently at 105 ℃

일반화된 오리피스의 유량예측 상관식 및 유량선도

최종민,김용찬,곽재수,권병철 대한설비공학회 2004 설비공학 논문집 Vol.16 No.10

With the phaseout of CFC and HCFC refrigerants, refrigeration and heat pump systems must be redesigned to match and improve system performance with alternative refrigerants. A generalized flow model for predicting mass flow rate through short tube orifices is derived from a power law form of dimensionless parameters generated by Pi-theorem. The database for developing the correlation includes extensive experimental data for R12, R22, R134a, R407C, R410A, and R502 from the open literature. The correlation yields an average deviation of 0.3% and a standard deviation of 6.1% based on the present database. In addition, rating charts for predicting refrigerant flow rate through short tube orifices are generated for R12, R22, R134a, R407C, R410A, and R502.

고온 조건에서 유량 계측 방법에 따른 오차

진상욱(Sangwook Jin),황기영(Giyoung Hwang),이규준(Kyujoon Lee),민성기(Seongki Min) 한국추진공학회 2014 한국추진공학회 학술대회논문집 Vol.2014 No.5

고온 환경에서 3 가지 방법으로 공기 유량을 계산하였다. 벨마우스, 레이크, 임계 유동 벤츄리 노즐을 이용하는 방법으로 CFD(Computational Fluid Dynamics) 해석 자료를 분석하였다. 고온 조건인 점을 고려하여 부력 효과를 적용한 상태에서 배관과 외부 공기의 대류에 의한 열전달 유무 차이를 두어 유량을 확인하였고, 각 조건에서 CFD 계산을 통해 얻어진 공기 유량을 기준으로 유량 계산 방법별 유출 계수(Discharge Coefficient)를 비교하여 유량의 정확도를 분석하였다. Three kinds of measurement methods for air mass flow rate was calculated on a high temperature condition. These are the method by using a bellmouth, a rake and a critical venturi nozzle. The test condition is simulated by CFD(Computational Fluid Dynamics) with or without insulator for the convection with ambient air. The air mass flow rate based on test conditions and the variation of discharge coefficient on measurement methods have been analyzed.

연료분무 및 연소 3 : 흡기유량에 따른 디젤엔진에서의 배출가스 특성에 대한 연구

김형준 ( Hyung Jun Kim ),박용희 ( Yong Hee Park ),엄명도 ( Myoung Do Eom ),고종민 ( Jong Min Koh ),황진우 ( Jin Woo Hwang ),이상현 ( Sang Hyun Lee ),길지훈 ( Ji Hun Keel ),김정수 ( Jeong Soo Kim ) 한국액체미립화학회 2012 한국액체미립화학회 학술강연회 논문집 Vol.2012 No.-

The investigation was conducted to analyze the exhaust emission characteristics in diesel engine according to intake air mass flow. In this study, the test diesel engine with a 5,899 cubic centimeter displacement and power of the 260ps was used to analyze the emission characteristics according to the intake air mass flow. In addition, the test modes were applied by the ND-13 and ETC mode. In order to analyze the emission characteristics, the engine dynamometer with 440kW and emission gas analyzer(AMA-4000) were utilized. From the experimental results, it is revealed that the NOx and HC emissions in the intake air mass flow of large amount have high levels compared to those in the intake air mass flow of small amount in the ND-13 mode. However, the PM emission was shown the opposite trend in the NOx and HC emission due to the trade-off relation between the NOx and PM.