• 한국가스학회지
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• 제23권3호
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• pp.1-6
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• 2019

본 연구는 폐기물 소각로에서 질소산화물 저감을 위해 고온의 배기가스를 연소로에서 재순환하여 연소용 공기와 혼합하여 배기가스 재순환을 이용한 방법에서 고온의 배기가스를 별도의 동력 팬이 없이 코안다 노즐을 이용한 배기가스 재순환 장치에 관한 연구이다. 코안다 노즐에서 공기 공급 노즐 간극의 변화와 공기 공급 노즐의 위치에 따른 배기가스 재순환 유량 특성과 혼합 가스의 출구에서 평균온도 변화를 살펴보았다. 공기 공급 노즐의 간극이 3.22, 4.03, 4.84 mm로 변할 때 가장 좁은 3.22 mm일 때가 배기가스 재순환 유량과 공기 공급 유량의 비인 배기가스 재순환 유량비가 2.227로 가장 재순환 유량이 크게 나타났고 혼합가스 평균 온도는 $594.8^{\circ}C$로 나타났다. 공기 공급 노즐의 위치가 코안다 노즐 목의 전방 위치, 목 위치, 확관 위치로 변할 때를 살펴보았으며 전방 위치와 목 위치일 때는 재순환 유량비가 1.843으로 거의 같은 값이고 확관 위치에서는 1.696으로 나타났으며 평균 온도는 $559.8^{\circ}C$와 $544.3^{\circ}C$로 나타났다.

• 한국환경과학회지
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• 제24권7호
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• pp.947-954
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• 2015

Dielectric barrier discharge plasma is a new technique in water pollutant degradation, which that is characterized by the production of chemically active species such as hydroxyl radicals, ozone, hydrogen peroxide, etc. If dissolving of plasma gas generated in the plasma reaction has increased, it is possible to increase the contaminant removal capacity. In this study, the improvement on the dissolving performance of plasma gas was evaluated by the indirect method measuring the overall oxygen transfer coefficient. Experiments were conducted to examine the effects of nozzle type, distance from water surface, air supply rate and liquid circulation rate. The experimental results showed that the $K_{La}$ value of the 3-prong nozzle is 2.67 times higher than the diffuser. The order of $K_{La}$ value with nozzle type ranked in the following order: 3-prong nozzle (inner diameter, less 1 mm) > circular nozzle (inner diameter, 1.5 mm) > ellipse nozzle (short diameter 1 mm, long diameter 2.5 mm) > circular nozzle (inner diameter, 3 mm). Optimal liquid circulation rate was appeared to be 1.7 L/min, the value of $K_{La}$ was 0.510 1/min. The value of $K_{La}$ with increasing air supply rate was revealed in the form of an exponential such as $K_{La}=0.3581e^{0.2919^*air\;flow\;rate}$.

• 한국환경과학회지
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• 제27권3호
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• pp.219-225
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• 2018

This study was conducted to investigate the possibility of utilizing various types of nozzles and gas-liquid mixers to increase the dissolution rate of plasma gas containing ozone generated in a dielectric barrier plasma reactor. After selecting the air atomizing nozzle with the highest gas dissolution rate among the 13 types of test equipment, we investigated the influence of the operating factors on the air atomizing nozzle to determine the optimal plasma gas dissolution method. The gas dissolution rate was measured by a simple and indirect method, specifically, the measurement of KLa instead of direct measurement of ozone concentration, which requires a longer analysis time. The results showed that the KLa value of the simple mix of air and water was $0.372min^{-1}$, Which is 1.44 times higher than that ($0.258min^{-1}$) of gas emitted from a normal diffuser. Among the nozzles of the same type, the KLa value was highest for the nozzle having the smallest orifice diameter. Among the 13 types of devices tested, the nozzle with highest KLa value was the M22M nozzle, which is a gas-liquid spray nozzle. The relationship between water circulation flow rate and KLa value in the experimental range was linear. The air supply flow rate and KLa value showed a parabolic-type correlation, while the optimum air supply flow rate for the water circulation flow rate of 1.8 L / min is 1.38 times.

• 한국분무공학회지
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• 제8권1호
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• pp.9-15
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• 2003

The liquid phase LPG injection (LPLI) system is considered as one of the next generation fuel supply systems for LPG, vehicles, since it can accomplish the higher power, higher efficiency, and lower emission characteristics than the existing mixer type fuel supply system. However, during the injection of liquid LPG fuel into the inlet duct of an engine, a large quantity of heat is extracted due to evaporation of fuel. A problem is that the moisture in the air freezes around the outlet of a nozzle, which is called icing Phenomenon. It may cause damage to the outlet nozzle of an injector. The frozen ice deposit detached from the nozzle also may cause a considerable damage to the inlet valve or valve seat. In this work, the experimental investigation of the icing phenomenon was carried out. The results showed that the icing phenomenon and process were mainly affected by humidity of inlet air instead of the air temperature in the inlet duct. Also, it was observed that the icing occurs first in the inlet of a nozzle, and grows considerably at the upper part of the nozzle inlet and the opposite side of the nozzle entrance. An LPG fuel, mainly consisting of butane, has lower latent heat of vaporization than that of propane, which is an advantage in controlling the icing phenomenon.

• 한국산학기술학회논문지
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• 제22권1호
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• pp.321-326
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• 2021

본 연구는 웨이퍼를 적재할 때 웨이퍼의 손상을 최소화 시키기 위한 기술이다. 반도체와 솔라셀에 이용되는 두께가 얇은 웨이퍼는 적재된 웨이퍼 사이의 표면 장력에 의해 웨이퍼의 분리를 어렵게 만들어 웨이퍼의 표면에 손상을 줄 수 있다. 이러한 웨이퍼의 손상을 최소화시키는 기술은 압축 공기를 웨이퍼 쪽으로 분사하고, 미소의 수평 이동 기구를 동시에 적용하는 것이다. 연구에 사용된 주요 실험 인자는 웨이퍼의 공급 속도, 압축 공기의 노즐 압력, 그리고 흡착 헤드의 흡착 시간이다. 실험 결과, 동일한 노즐 압력에서 웨이퍼의 공급 속도가 빠를수록 파손율이 증가하고, 동일한 공급 속도에서는 노즐 압력이 낮을수록 파손율이 증가한다. 그리고, 웨이퍼를 흡착시키데 필요한 시간은 어느 수준 이상이면 웨이퍼의 공급 속도에 따른 파손율에는 큰 영향을 미치지 않는다. 본 연구의 실험 범위 안에서 최적의 실험 조건은 웨이퍼의 공급 속도 600 ea/hr, 압축 공기의 노즐 압력 0.55 MPa, 흡착 헤드의 흡착 시간 0.9 sec 이다. 또한, 반복성능 실험을 통해 개선된 기술은 웨이퍼의 파손율을 최소화시킬 수 있음을 보여 주었다.

• 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.

• 한국분무공학회지
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• 제8권2호
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• pp.1-6
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• 2003

The liquid phase LPG injection (LPLI) system (the third generation technology) has been considered as one of the next generation fuel supply systems for LPG vehicles, since it has a very strong potential to accomplish the higher power, higher efficiency, and lower emission characteristics than the mixer type(the second generation technology) fuel supply system However. when a liquid LPG fuel is injected into the inlet duct of an engine, a large quantity of heat is extracted due to evaporation of fuel. This leads to freezing of the moisture in the air around the outlet of a nozzle, which is called icing phenomenon. It may cause damage to the outlet nozzle of an injector or inlet valve seat. In this work, the experimental investigation of the icing phenomenon was carried out The results showed that the icing phenomenon and process were mainly affected by humidity of inlet air instead of air temperature in the inlet duel. Also, it was observed that the total ice formed around the nozzle weighs at about $150mg{\sim}260mg$ after injection for ten minutes. And some fuel species were found in the ice attached at the front side of a nozzle, while frozen ice attached at the back of a nozzle was mostly' consisted of moisture of inlet air. Therefore, some frozen ice deposit. detached from front nozzle of an injector, may cause a problem of unfavorable air fuel ratio control in the small LPLI engine.

• 한국분무공학회지
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• 제13권3호
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• pp.126-133
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• 2008

The atomization characteristics of the dual air supplying two-fluid nozzle were investigated experimentally using PIV and PDA systems. The twin-fluid nozzle is composed of three main parts: the feeding injector to supply fluid that is controlled by a PWM (pulse-width modulation) mode, the adaptor as a device with the ports for supplying the carrier and assist air, and the main nozzle to produce sprays. The main nozzle has the swirler with four equally spaced tangential slots, which gives the injecting fluid an angular momentum. The swirl angle in the swirler varied with $0^{\circ}$, $30^{\circ}$, $60^{\circ}$ and $90^{\circ}$. The ratios of carrier air to assist air and ALR (total air to liquid) were 0.55 and 1.23, respectively. The macroscopic behavior of the spray was investigated using PIV system, and the AMD and SMD distributions of the sprays were measured using PDA system. As a result, the SMD distribution increases along the radial distance, and it decreases with the increase of swirl angle in swirler.

• 농업과학연구
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• 제7권2호
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• pp.156-168
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• 1980

분무기(噴霧機) nozzle의 와실내(渦室內)에서 공기(空氣)를 수류(水流)의 중심부(中心部)로 분무(噴霧)시켜 예비미립화(豫備微粒化) 및 공기충돌식(空氣衝突式)의 미립화방식(微粒化方式)을 복합(復合)하여 고안(考案)된 air-center nozzle의 분무살포량(噴霧撒布量)의 분포도(分布度)와 분출량(噴出量)의 특성(特性)을 찾기위한 실험(實驗)을 실시(實施)하였다. 공기량(空氣量)은 소구경(小口徑) pipe 직경(直徑) 0.45mm부터 1.42mm이내로 7 수준(水準)으로 조절(調節)하였고 이의 각수준별(各水準別)로 압력(壓力)을 $0.35kg/cm^2$(5 psi)부터 $6.33kg/cm^2$(90 psi)까지 11 수준(水準)으로 조절(調節)하였다. 매실험결과(每實驗結果)는 표준(標準) nozzle 실험치(實驗値)와 비교분석(比較分析)하였고 이의 결과(結果)는 다음과 같다. Air-center nozzle은 비교적(比較的) 표준(標準) nozzle보다 안정(安定)된 살포량(撒布量) 분포형(分布型)을 유지(維持)하였다. Air-center nozzle의 분무살포량(噴霧撒布量) 분포도(分布度)는 공기량(空氣量)이 증가(增加)함에 따라서 중심부분(中心部分)으로 집중화(集中化)하였고 이 집중화정도(集中化程度)는 표준(標準) nozzle보다도 더 컸다. 이현상(現象)은 표준(標準) nozzle에 비(比)하여 도달성(到達性) nozzle형(型)에 적합(適合)함을 시사하였다. Air-center nozzle의 분출량(噴出量)은 어느 일정(一定)한 수준(水準) 이내(以內)에서 공기량(空氣量)때문에 표준(標準) nozzle의 분출량(噴出量)만큼 크지는 못하였다. 분출량(噴出量)의 감소율(減少率)은 압력(壓力)이 증가(增加)함에 따라서 둔화되었고 혼합용제(混合溶劑)속의 공기함유율(空氣含有率)이 2~3%인 저비율(低比率)일때 급속(急速)히 컸다. 이 현상(現象)은 공기(空氣)의 압축성질(壓縮性質)에 기인(基因)된 것으로 사료(思料)된다.

• 한국분무공학회지
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• 제2권2호
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• pp.35-42
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• 1997

An innovating technique of atomizer has been proposed to supply and to atomise molten materials. Both of a simple geometry of nozzle and an improved nozzle have been fabricated in the present study. With these nozzles, characteristics of the suction and disintegration have been empirically investigated. The important conclusions are as follows; In the case of a simple nozzle: 1) Although the sucking up and supplying of molten materials are available, the applications of powder metallurgy are limited. 2) It is concluded that the more air flow rate, $W_A$ or the shorter the height of air nozzle from the surface of supplied water, $L_h$, the more the atomizing mass of liquids, $W_L$. In the case of an improved nozzle: 3) The stable liquids can be supplied due to cut off the passage of surrounding air entrainment by air jets. 4) The atomizing mass of liquids, $W_L$ has affected not so much on the height of nozzle from the surface of supplied water, $L_h$ as that from the orifice, hc.