• Title/Summary/Keyword: Water atomization

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A Study of the Thickness Characteristics of the Liquid Sheet Formed by an Impinging Jet onto a Plate (평판 충돌 제트로 생성되는 액막의 두께 분포 특성 연구)

  • Kim, M.S.;Oh, J.H.;Jeong, H.M.;Kang, B.S.
    • Journal of ILASS-Korea
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    • v.27 no.2
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    • pp.77-83
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    • 2022
  • In this study, the thickness of the liquid sheet formed by a low speed impinging jet onto a flat plate was measured by the direct contact method. The spatial distribution characteristics of the sheet thickness in the radial and circumferential directions, and the effects of jet velocity and liquid viscosity were analyzed. The measurement results were compared with the theoretical predictions. The wavy surface was observed in the case of low viscosity water, but not in the high viscosity aqueous glycerol solutions. The sheet thickness increased as the circumferential angle increased or the distance from the impinging point increased, but the thickness decreased as the circumferential angle increased around the impinging point. As the jet speed increased, the sheet thickness decreased, and the sheet thickness increased as the liquid viscosity increased. Comparison with the theoretical predictions showed that the measurement results agreed well in the case of low viscosity water or high viscosity liquids around the impinging point. The distribution characteristics of the sheet thickness can provide useful means for prediction of spray characteristics in splash plate injectors.

Development of the Real-time Concentration Measurement Method for Evaporating Binary Mixture Droplet using Surface Plasmon Resonance Imaging (표면플라즈몬공명 가시화 장치를 이용한 증발하는 이종혼합물 액적의 실시간 농도 가시화 기법 개발)

  • Jeong, Chan Ho;Lee, Hyung Ju;Choi, Chang Kyoung;Lee, Hyoungsoon;Lee, Seong Hyuk
    • Journal of ILASS-Korea
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    • v.26 no.4
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    • pp.212-218
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    • 2021
  • The present study aims to develop the Surface Plasmon Resonance (SPR) imaging system facilitating the real-time measurement of the concentration of evaporating binary mixture droplet (BMD). We introduce the theoretical background of the SPR imaging technique and its methodology for concentration measurement. The SPR imaging system established in the present study consists of a LED light source, a polarizer, a lens, and a band pass filter for the collimated light of a 589 nm wavelength, and a CCD camera. Based on the Fresnel multiple-layer reflection theory, SPR imaging can capture the change of refractive index of evaporating BMD. For example, the present study exhibits the visualization process of ethylene glycol (EG)-water (W) BMD and measures real-time concentration change. Since the water component is more volatile than the ethylene glycol component, the refractive index of EG-W BMD varies with its mixture composition during BMD evaporation. We successfully measured the ethylene glycol concentration within the evaporating BMD by using SPR imaging.

1-D Modeling of Heater Surface Temperature Distribution in EHC-based Urea-SCR System (EHC 기반 Urea-SCR 시스템 히터 표면온도 분포의 1-D 모델링)

  • Park, Sunhong;Son, Jihyun;Moon, Seoksu;Oh, Kwangchul;Jang, Sungwook;Park, Sungsuh
    • Journal of ILASS-Korea
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    • v.27 no.1
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    • pp.11-17
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    • 2022
  • In upcoming Post Stage-V and Tier 5 regulations of construction machineries, nitrogen oxide (NOx) emissions are strictly limited in cold start conditions. In response to this, a method of improving NOx conversion efficiency has been applied by installing an electric heating catalyst (EHC) in front of conventional urea-SCR systems so that the evaporation and thermal decomposition of urea-water solution can be promoted in cold start conditions. In this strategy, the evaporation and thermal decomposition of urea-water solution and corresponding NOx conversion efficiency are governed by temperature conditions inside the EHC. Therefore, characterizing the temperature distribution in the EHC under various operating conditions is crucial for the optimized operation and control of the EHC in Urea-SCR systems. In this study, a 1-D modeling analysis was performed to predict the heater surface temperature distribution in EHC under various operating conditions. The reliability of prediction results was verified by comparing them with measurement results obtained using an infrared (IR) camera. Based on 1-D analysis results, the effects of various EHC operation parameters on the heater surface temperature distribution were analyzed and discussed.

Experimental Investigation on the Thermal Performance Enhancement of Cooling System for Vehicles using Water/Coolant-Based Al2O3 Nanofluids (물/부동액-기반Al2O3나노유체를 이용한 차량용 냉각시스템 성능 향상에 관한 실험적 연구)

  • Park, Y.-J.;Kim, H.J.;Lee, S.-H.;Choi, T.J.;Kang, Y.J.;Jang, S.P.
    • Journal of ILASS-Korea
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    • v.20 no.2
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    • pp.65-69
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    • 2015
  • In this study, the thermal performance of vehicle's cooling system is experimentally investigated using the water/coolant-based $Al_2O_3$ nanofluids as working fluids. For the purpose, the water/coolant-based $Al_2O_3$ nanofluids are prepared by twostep method with gum arabic. In order to obtain the well-suspended nanofluids, the agglomerated $Al_2O_3$ nanoparticles are precipitated using centrifugal force and the experiments are performed with supernatant of them. The thermal conductivity is measured by transient hot wire method and the thermal conductivity of nanofluids is enhanced up to 4.8% as compared to that of base fluids. Moreover, the cooling performance of water/coolant-based $Al_2O_3$ nanofluids is evaluated using vehicle's engine simulator under the constant RPM condition. The results show that the cooling performance of automobile engine increases up to 5.9% using prepared nanofluids. To investigate the effect of nanofluids on exhaust gas, the $NO_x$ emission is measured during the operation with respect to time and 10.3% of $NO_x$ emission is decreased. The experimental results imply that the water/coolant-based $Al_2O_3$ nanofluids might be used as a next-generation vehicles' coolant

Combustion Characteristics of MDO and MDO Emulsion in Automotive Diesel Engine (선박 디젤유 및 선박 디젤유 에멀젼을 이용한 자동차용 디젤엔진의 연소특성)

  • Park, Jin-Kyu;Oh, Jung-Mo;Kim, Hyung-Ik;Lee, Chang-Hee;Lee, Ki-Hyung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.36 no.9
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    • pp.945-951
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    • 2012
  • A water emulsion fuel can be used to reduce soot and NOx emissions simultaneously because it has a lower combustion temperature and better fuel atomization owing to the evaporative latent heat and microexplosion of water. Moreover, it can be used without making special modifications to conventional diesel engines. Therefore, this fuel has attracted considerable research attention. In addition, lower-grade fuels are being considered for use in conventional engines because of an increase in oil prices. In this study, we investigated the combustion and exhaust characteristics of MDO (marine diesel oil), which has a lower grade than common diesel oil, and ME (MDO water emulsion) under various test conditions in an automotive diesel engine.

Moisture Adsorption Preventative Effect of Fermented Red Ginseng Extract Spherical Granules by Using Hydrophobic Compounds (홍삼의 지용성 성분을 이용한 발효홍삼 농축액 알갱이의 흡습방지 효과)

  • Shin, Myung-Gon
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.45 no.8
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    • pp.1153-1161
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    • 2016
  • For prevention of moisture adsorption, the fermented red ginseng extract spherical granules were coated by using hydrophobic fractions. The hydrophobic parts were extracted from red ginseng such as the perfect soluble part in 90% ethanol (PSE) and non-soluble part in hot water (NSHW). The optimum operating conditions for making fermented red ginseng extract spherical granules coated with PSE were a feeding rate (FR) of 0.49 mL/min, atomization air pressure (AP) of 2.14 bar, and product temperature (PT) of $48.96^{\circ}C$., whereas conditions for granules coated with NSHW were a FR of 0.61 mL/min, AP of 2.75 bar, and PT of $46.30^{\circ}C$. The solubility of coated fermented red ginseng extract spherical granule was lower than that of not coated. The fermented red ginseng extract spherical granules coated with NSHW showed more preventative effects for moisture adsorption than those coated with PSE, although there were no differences in solubility and fluidity. In the sensory evaluation, granules coated with hydrophobic fractions extracted from red ginseng were shown to be bitterer and less soluble than those not coated spherical granules. In conclusion, fermented red ginseng extract spherical granules coated with hydrophobic extracts from red ginseng showed a preventative effect against moisture.

An application of the electrostatic spray technology to increase scrubbing efficiency of SO$_{2}$ emitted from thermal systems (열시스템에서 생성된 SO$_{2}$ 가스의 배출저감을 위한 정전기 분무 원리의 응용)

  • Jeong, Jae-Yun;Byeon, Yeong-Cheol;Hwang, Jeong-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.8
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    • pp.1068-1076
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    • 1997
  • Emission control of acid exhaust gases from coal-fired power plants and waste incinerators has become an increasing concern of both industries and regulators. Among those gaseous emissions, SO$_{2}$ has been eliminated by a Spray Drying Absorber (SDA) system, where the exhaust gas is mixed with atomized limestone-water slurry droplets and then the chemical reaction of SO$_{2}$ with alkaline components of the liquid feed forms sulfates. Liquid atomization is necessary because it maximizes the reaction efficiency by increasing the total surface area of the alkaline components. An experimental study was performed with a laboratory scale SDA to investigate whether the scrubbing efficiency for SO$_{2}$ reduction increased or not with the application of a DC electric field to the limestone-water slurry. For a selected experimental condition SO$_{2}$ concentrations exited from the reactor were measured with various applied voltages and liquid flow rates. The applied voltage varied from -10 to 10 kV by 1 kV, and the volume flow rate of slurry was set to 15, 25, 35 ml/min which were within the range of emission mode. Consequently, the SO$_{2}$ scrubbing efficiency increased with increasing the applied voltage but was independent of the polarity of the applied voltage. For the electrical and flow conditions considered a theoretical study of estimating average size and charge of the atomized droplets was carried out based on the measured current-voltage characteristics. The droplet charge to mass ratio increased and the droplet diameter decreased as the strength of the applied voltage increased.

Performance and Emission Studies in a DI Diesel Engine Using Wood Pyrolysis Oil-Bio Diesel Emulsion (목질계 열분해유-바이오 디젤 유상액을 사용하는 직접분사식 디젤 엔진의 엔진성능 및 배기특성에 관한 연구)

  • Lee, Seokhwan
    • Journal of ILASS-Korea
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    • v.17 no.4
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    • pp.197-204
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    • 2012
  • The vast stores of biomass available in the worldwide have the potential to displace significant amounts of fuels that are currently derived from petroleum sources. Fast pyrolysis of biomass is one of possible paths by which we can convert biomass to higher value products. The wood pyrolysis oil (WPO), also known as the bio crude oil (BCO), has been regarded as an alternative fuel for petroleum fuels to be used in diesel engine. However, the use of WPO in a diesel engine requires modifications due to low energy density, high water contents, low acidity, and high viscosity of the WPO. One of the easiest way to adopt WPO to diesel engine without modifications is emulsification of WPO with diesel or bio diesel. In this study, a DI diesel engine operated with diesel, bio diesel (BD), WPO/BD emulsion was experimentally investigated. Performance and gaseous & particle emission characteristics of a diesel engine fuelled by WPO/BD emulsion were examined. Results showed that stable engine operation was possible with emulsion and engine output power was comparable to diesel and bio diesel operation.

A Study of the Behavior of Droplet Impacting on a Horizontal Wire (수평 와이어와 충돌하는 액적 거동에 관한 연구)

  • Kang, W.J.;Kim, J.Y.;Park, J.H.;Kang, B.S.
    • Journal of ILASS-Korea
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    • v.25 no.3
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    • pp.103-110
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    • 2020
  • In this study, the behavior of water droplet impacting on a thin horizontal wire was visualized by time-delay photography. The impact behavior modes, critical capture speed and trapped mass were analyzed by changing the droplet size, velocity, wire diameter and eccentricity ratio. As the Weber number increased, the hanging, merging, and splitting modes appeared sequentially for the case of central impact, and the hanging and non-splitting modes appeared for the case of off-center impact. The boundary We number of each mode was affected by the diameter ratio. The critical capture speed was affected much by the degree of eccentricity. For all diameter ratios, it was higher for the case of central impact than for off-center impact. The trapped mass was larger for the case of central impact than for off-center impact and it increased with the smaller We number and the larger diameter ratio.

A Study on Spray and Mixing Characteristics of Unlike Impinging Triplet Injector (F-O-F, O-F-O) (충돌형(F-O-F, O-F-O) 실물형 분사기의 분무특성 및 혼합특성에 관한 연구)

  • 김종규;김승한;문일윤;이광진;서성현;한영민
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2003.10a
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    • pp.195-203
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    • 2003
  • Spray and Mixing characteristics of the unlike impinging triplet injectors (F-O-F, O-F-O) were investigated with the variation of the momentum ratio of oxidizer to fuel. The spray pattern was measured using a backlit stroboscopic photography technique, and mixing efficiency was measured using a mechanical patternator. Kerosene/water were used as a propellant simulant. From the experimental results, it is found that a O-F-O type injector has a good atomization. And as the momentum ratio increases, the mixing efficiency decreases rapidly.

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