• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1999년도 제13회 학술강연논문집
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• pp.36-36
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• 1999

일반적으로 이젝터(ejector)는 노즐로부터 팽창하는 높은 운동량을 가지는 주 유동과 주변의 낮은 운동량을 가지는 유동사이에서 생기는 강한 전단력을 이용하여, 분류 주변의 유체를 보다 고압의 부분까지 압축하여 수송하는 장치이다. 이젝터는 노즐(nozzle)과 디퓨저(diffuser)로 되어 있으며, 회전부분이나 활동부분을 가지지 않는 유체기계이므로 고장이 적고, 소형임에도 불구하고 대용량의 유체를 압축할 수 있는 특징을 가지고 있다. 그러나 이젝터의 구동은 유체의 전단력만을 이용하므로 효율이 낮은 단점이 있으므로, 이젝터 형상의 최적설계 및 성능개선을 위한 연구가 필요하다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.329-334
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• 2001

In order to investigate the operating characteristics of a supersonic steam ejector, the axisymmetric, compressible, Reynolds-averaged, Navier-Stokes computations are performed using a finite volume method. The secondary and back pressures of the ejector system with a second throat are changed to investigate their effects on the suction mass flow. Three operation modes of the steam ejector system, the critical mode, subcritical mode and back flow mode, are discussed to predict the critical suction mass flow. The present computations are validated with some experimental results. The secondary and back pressures of the supersonic steam ejector significantly affect the critical suction mass flow. The present computations predict the experimented critical mass flow with fairly good accuracy. A good correlation is obtained for the critical suction mass flow. The present results show that provided the primary nozzle configuration and secondary pressure are known, we can predict the critical mass flow with good accuracy.

• 한국가시화정보학회지
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• 제9권2호
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• pp.54-60
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• 2011

This paper is a basic study on volatile organic compounds(VOC) recovery system in a crude oil carrier. VOC is easily evaporated in cargo tankers during loading and transportation of crude oil, causes serious environmental contamination and a huge economic loss. An ejector system is designed to mix VOC gas into crude oil flow to reduce VOC concentration. Detail two-phase flow inside the ejector is simulated using a commercial CFD code. To verify the numerical prediction, a scale-down experiment is conducted. Instead of crude oil and VOC, water and air are used as the working fluids. Flow characteristics and main parameters are obtained by two-phase flow visualization and PIV measurements. Air volume flow rate induced by the ejector is compared with respect to the volume flow rate of water using experimental and numerical results. Overall performance of the two-phase ejector predicted by the CFD simulation agrees well with that of the experiment.

• 한국태양에너지학회 논문집
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• 제34권4호
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• pp.45-50
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• 2014

In this paper, the Ocean Thermal Energy Conversion(OTEC) with vapor-vapor ejector is proposed newly. At this OTEC system, a vapor-vapor ejector is installed at inlet of condenser. The vapor-vapor ejector plays a very important role in increasing of the production work of low-stage turbine throughout the decrement of outlet pressure of ejector. The performance analysis is conducted for optimizing the system with HYSYS program. The procedure of performance analysis consists of outlet pressure of high turbine, the mass ratio of working fluid at separator, total working fluid rate, and nozzle diameters of vapor-vapor ejector. The main results is summarized as follows. The nozzle diameter is most important thing in this study. When each nozzle diameter of vapor-vapor ejector is 10 mm, the efficiency of OTEC system with vapor-vapor ejector shows the highest value. So it is necessary to set the optimized nozzle diameters of vapor-vapor ejector for achieving the high efficiency OTEC power system.

• 설비공학논문집
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• 제28권11호
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• pp.434-443
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• 2016

The evaporation of water from an aqueous solution is widely used in the food, desalination, pulp, and chemical industries. Usually, a large amount of energy is consumed in the evaporation process to boil off water due to atmospheric pressure. As a way of improving the energy efficiency of the evaporation process, the combination of multiple effect evaporation and thermal vapor recompression has been proposed and has become a successful technique. In this study, 4 multiple-effect falling film type evaporators for sugar solution are designed and the energy efficiency of the system is analyzed in response to the selection of the steam ejector position. Energy efficiency is increased and vapor is more compressed in the steam ejector as the Thermal Vapor Recompression (TVR) is arranged in the rear part of the evaporator system. A simplified 0-dimensional evaporator model is developed using non-linear equations derived from mass balances, energy balances, and heat transfer equations. Steam economy is calculated to compare the evaporation performance of the 4 proposed evaporators. The entrainment ratio, compression ratio, and expansion ratio are computed to check the ejector performance.

• Journal of Advanced Marine Engineering and Technology
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• 제32권4호
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• pp.550-556
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• 2008

The aim of this research is to analyze the influence of motive pressure, driving nozzle position and nozzle throat ratio on the performance of ejector. The experiment was conducted in the variation of motive pressure of 0.196, 0.294, 0.392 and 0.490MPa respectively. The position of driving nozzle was varied in difference locations according to mixing tube diameter(0.5d, 1d, 2d, 3d, 4.15d, 5d and 6d). The experimental results show when the nozzle outlet is located at 3d, the flow characteristics change abruptly. It is shown that the suction flow rate and pressure lift ratio of ejector is influenced by the driving nozzle position. At nozzle position location of the Id of mixing tube diameter the performance of ejector gives the best performance.

• 설비공학논문집
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• 제23권7호
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• pp.505-512
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• 2011

Recently, many researchers have analyzed the performance of the transcritical $CO_2$ refrigeration cycle in order to identify opportunities to improve the system energy efficiency. The reduction of the expansion process losses is one of the key issues to improve the efficiency of the transcritical $CO_2$ refrigeration cycle. In this study, the analytical study on the performance characteristics of $CO_2$ cycle with an ejector carried out with a variation of outdoor temperature, gascooler inlet air velocity, evaporator inlet air velocity, and evaporator inlet air temperature. As a result, the system performance could be improved over 85% by using an ejector for various operating condition because of the reduction of compressor work. Moreover, the cooling capacity increased about 18% for variable outdoor condition. Therefore, the high performance of an ejector system could be maintained for wide operating conditions and system reliability could be improved compared to that of a basic system.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2005년도 제24회 춘계학술대회논문집
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• pp.405-408
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• 2005

혼합챔버 내에서 패브리-초킹(Fabri-chocking)이 발생한다는 가정을 이용하여 이차목을 갖는 환형분사 초음속 이젝터의 이론 해석을 수행하였다. 부유동 압력을 예측하기 위해 혼합챔버 입구에서 패브리-초킹면 사이를 비혼합이론(non-mixing theory)을 이용하여 계산하였다. 혼합챔버의 수축각에 의해 발생하는 깔때기 모양의 경사충격파를 이차원 경사충격파로 모사하였고, 패브리-초킹면의 주유동에만 영향을 미친다고 가정하였다. 그 결과 혼합챔버의 수축각이 4도보다 작은 조건에서 실험값을 잘 예측하는 것을 확인하였다.

• 항공우주기술
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• 제3권1호
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• pp.65-78
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• 2004

본 연구는 램제트 엔진 성능시험기의 설계기술 습득을 위하여 진행된 연구의 일부분으로 자유제트 형식 시험기의 설계기술을 연구한 결과를 정리한 것이다. 연구의 대상은 램제트 엔진 성능시험기의 범용 설비인 오염공기 방식 가열기(Vitiated Air Heater), 시험부, 디퓨저, 이젝터 등으로 설계기법 및 설치기법들을 중점으로 연구하였다. 램제트 엔진 성능시험기 시험부는 기본 성능시험기의 작동 영역(마하2~5, 고도0~25km)을 토대로 10개의 작동점으로 재구성하여 각 작동점에서의 마하수, 고도에 따른 시험장치의 초음속 노즐, 디퓨저, 이젝터 등 주요 구성요소들의 물성치(온도, 압력 등)를 계산하였으며, 성능시험기의 구동 방법 등에 대한 내용을 기술하였다.

• 한국분무공학회지
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• 제3권2호
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• pp.14-23
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• 1998

The negative pressure as much as 10's mmHg is demanded at nozzle inside, in case of atomizing the large density molten materials. by conventional air jet nozzle. In this study, suction type fluid nozzle is designed by applying the ejector principle in order to clarify the air flow of nozzle inside, mechanism of liquid suction and liquid film formation. The results of this experimental study areas follows. Suction force of liquid is magnified by using liquid nozzle, and it is able to supply the liquid stable. Negative pressure at nozzle inside is varied by throttle angle of liquid nozzle, position and outer diameter of air jet nozzle, and have a influence on liquid suction quantity and liquid film formation.