• Title/Summary/Keyword: Liquid Layer

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Monitoring of the Transfer of Tetrachloroaurate(III) Ions by Thin-layer Electrochemistry and Electrochemical Deposition of Metallic Gold over a Graphite Electrode

  • Song, Ji-Seon;Shin, Hyo-Sul;Kang, Chan
    • Bulletin of the Korean Chemical Society
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    • v.29 no.10
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    • pp.1983-1987
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    • 2008
  • This study demonstrates the electrochemical conversion of the synthetic procedure of monolayer-protected clusters using a thin toluene layer over an edge plane pyrolytic graphite electrode. A thin toluene layer with a thickness of 0.31 mm was coated over the electrode and an immiscible liquid/liquid water/toluene interface was introduced. The transfer of the tetrachloroaurate ($AuCl_4^-$) ions into the toluene layer interposed between the aqueous solution and the electrode surface was electrochemically monitored. The $AuCl_4^-$ ions initially could not move through into the toluene layer, showing no reduction wave, but, in the presence of the phase transfer reagent, tetraoctylammonium bromide (TOABr), a cathodic wave at 0.23 V vs. Ag/AgCl was observed, indicating the reduction of the transferred $AuCl_4^-$ ions in the toluene layer. In the presence of dodecanethiol together with TOABr, a self-assembled monolayer was formed over the electro-deposited metallic gold surface. The E-SEM image of the surface indicates the formation of a highly porous metallic gold surface, rather than individual nanoparticles, over the EPG electrode.

Experimental Study on Liquid Desiccant Distribution Characteristics at a Dehumidifier with Extended Surface (확장표면을 적용한 액체식 제습기에서 제습액 분배 특성에 관한 실험적 연구)

  • Lee, Min-Su;Chang, Young-Soo;Lee, Dae-Young
    • Proceedings of the SAREK Conference
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    • 2009.06a
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    • pp.645-649
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    • 2009
  • Liquid desiccant cooling technology can supply cooling by using waste heat and solar heat which are hard to use effectively. For compact and efficient design of a dehumidifier, it is important to sustain sufficient heat and mass transfer surface area for water vapor diffusion from air to liquid desiccant on heat exchanger. In this study, the plate type heat exchanger is adopted which has extended surface, and hydrophilic coating and porous layer coating are adopted to enhance surface wettedness. PP(polypropylene) plate is coated by porous layer and PET(polyethylene terephthalate) non-woven fabric is coated by hydrophilic polymer. These coated surfaces have porous structure, so that falling liquid film spreads widely on the coated surface foaming thin liquid film by capillary force. The temperature of liquid desiccant increases during dehumidification process by latent heat absorption, which leads to loss of dehumidification capacity. Liquid desiccant is cooled by cooling water flowing in plate heat exchanger. On the plate side, the liquid desiccant can be cooled by internal cooling. However the liquid desiccant on extended surface should be moved and cooled at heat exchanger surface. Optimal mixing and distribution of liquid desiccant between extended surface and plate heat exchanger surface is essential design parameter. The experiment has been conducted to verify effective surface treatment and distribution characteristics by measuring wall side flow rate and visualization test. It is observed that hydrophilic and porous layer coating have excellent wettedness, and the distribution can be regulated by adopting holes on extended surface.

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Effects of Electrolytes in a Liquid Thin Layer System

  • Chung, Taek-Dong
    • Journal of the Korean Electrochemical Society
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    • v.5 no.4
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    • pp.216-220
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    • 2002
  • The effects of electrolytes on electrochemical behavior from an oil thin layer interposed between a graphite electrode and an aqueous solution phase were examined. A hydrophobic electroactive species, tetrachloro-1,4-benzoquinone (TCQ), in a benzonitrile (EN) layer was employed to study ion transfer properties across the BN-water interface. Experimental results showed that hydrophobic cations as well as anions could be successfully used as ionic charge carriers. The addition of various salts into either the oil layers or the aqueous solutions offers deeper insight for the electrochemistry of the liquid thin layer system. When aqueous perchloric acid is interfaced with the BN films, the perchlorate ion of tetrahexylammonium perchlorate (THAP) substantially suppresses the dissociated proton concentration in the layer by the common ion effect while there is only a little change in the total acid concentration. Further approach by theoretical calculation makes it possible to quantitatively understand the effect of the electrolytes to the electrochemical responses of TCQ, which were previously reported (Anal. Chem. 73, 337 (2001)).

A Study on the Boundary Layer Thickness at a Liquid-Vapor Interface (기액계면의 경계층 두께에 관한 연구)

  • Choi, Soon-Ho;Song, Chi-Sung;Choi, Hyun-Kyu;Lee, Jung-Hye;Kim, Kyung-Kun
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1086-1091
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    • 2004
  • The boundary layer is a very important characteristic of a liquid-vapor interface since it governs the heat and mass transfer phenomena across an interface. However, the thickness of a boundary layer is generally micro- or nano-sized, which requires highly accurate measurement devices and, consequently, costs the related experiments very high and time-consuming. Due to these size dependent limitations, the experiments related with a nano-scaled size have suffered from the errors and the reliability of the obtained data. This study is performed to grasp the characteristics of a liquid-vapor interface, by using a molecular dynamics method. The simulation results were compared with other studies if possible. Although other studies reported that there existed a temperature discontinuity over an interface when the system was reduced to micro- or nano-sized, we confirmed that there was no such a temperature discontinuity.

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Effects of boundary layer and liquid viscosity and compressible air on sloshing characteristics

  • Zou, Chang-Fang;Wang, De-Yu;Cai, Zhong-Hua
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.4
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    • pp.670-690
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    • 2015
  • In this paper, numerical investigations for tank sloshing, based on commercial CFD package FLUENT, are performed to study effects of boundary layer grid, liquid viscosity and compressible air on sloshing pressure, wave height and rising time of impact pressure. Also, sloshing experiments for liquids of different viscosity are carried out to validate the numerical results. Through comparison of numerical and experimental results, a computational model including boundary layer grid can predict the sloshing pressure more accurately. Energy dissipation due to viscous friction leads to reduction of sloshing pressure and wave elevation. Sloshing pressure is also reduced because of cushion effect of compressible air. Due to high viscosity damping effect and compressible air effect, the rising time of impact pressure becomes longer. It is also found that liquid viscosity and compressible air influence distribution of dynamic pressure along the vertical tank wall.

A Study of Liquid Crystal Alignment Layer Using Brewster Angle Microscope (Brewster Angle Microscope를 이용한 액정 배향막 연구)

  • 정치섭
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.12 no.1
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    • pp.81-87
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    • 1999
  • The surface morphology of liquid crystal alignment layer has been investigated by using Brewster angle microscope(BAM) for the first time. The samples used in this work for liquid crystal alignment layer were mechanically rubbed polyimide films. The rubbing pattern on this layer has been analyzed with the terms of microgroove and rubbing induced optical birefringence. For the mechanically rubbed surface, the geometrical factors of microgroove play the major role for the formation of rubbing pattern. We propose that the BAM can be used as a powerful tool not only for observing the rubbing pattern, but also for inspecting the surface defects.

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Dependence of Dielectric Layer and Electrolyte on the Driving Performance of Electrowetting-Based Liquid Lens

  • Lee, June-Kyoo;Park, Kyung-Woo;Kim, Hak-Rin;Kong, Seong-Ho
    • Journal of Information Display
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    • v.11 no.2
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    • pp.84-90
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    • 2010
  • This paper presents the effects of a dielectric layer and an electrolyte on the driving performance of an electrowetting on dielectric (EWOD)-based liquid lens. The range of tunable focal length of the EWOD-based liquid lens was highly dependent on the conditions of the dielectric layer, which included an inorganic oxide layer and an organic hydrophobic layer. Moreover, experiments on the physical and optical durability of electrolyte by varying temperature conditions, were conducted and their results were discussed. Finally, the lens with a truncated-pyramid silicon cavity having a sidewall dielectrics and electrode was fabricated by anisotropic etching and other micro-electromechanical systems (MEMS) technologies in order to demonstrate its performance. The lens with $0.6-{\mu}m$-thick $SiO_2$ layer and 10 wt% LiCl-electrolyte exhibited brilliant focal-length tunability from infinity to 3.19 mm.

Parametric Investigation on Double Layer Liquid Coating Process with Viscous Dissipation in Optical Fiber Mass Manufacturing System (광섬유 대량생산시스템 이중 액상코팅공정의 점성소산 및 공정인자 영향성 해석연구)

  • Kim, Kyoungjin;Park, Joong-Youn
    • Journal of the Semiconductor & Display Technology
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    • v.17 no.4
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    • pp.80-85
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    • 2018
  • The present investigation on optical fiber mass manufacturing features the computational modeling and simulation on a double layer liquid coating process on glass fiber surface. The computational model employs a simplified geometry of typical fiber coating system which consists of primary and secondary coating dies along with secondary coating cup. The viscous dissipation in coating flow is incorporated into the double layer coating process simulations. Heavy temperature dependence of coating liquid viscosity is also considered in the model. The computational results found that the effects of viscous dissipation on both primary and secondary coating layer thicknesses are highly significant at higher drawing speed. Several important coating process parameters such as supply temperature and pressure of primary and secondary coating liquids are investigated and discussed in order to appreciate how those parameters affect the double layer coating layer thickness on fast moving glass fiber.

Fabrication of a microlens array using a birefringent layer and ferroelectric liquid crystal

  • Lee, Yong-Min;Lee, Kwang-Ho;Choi, Yoon-Seuk;Kim, Jae-Hoon
    • 한국정보디스플레이학회:학술대회논문집
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    • 2007.08a
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    • pp.109-112
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    • 2007
  • A new concept of the microlens array is fabricated using a birefringent layer on the concave microlens array. The stacked layers of liquid crystalline polymer (LCP) and the UV epoxy focus an incident light due to the surface relief structure. The ferroelectric liquid crystal layer was added to control the focusing intensity with a fast switching time.

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Melting Heat Transfer of Liquid Ice in a Rectangular Vessel with Heated Top Wall (구형용기내 상부면가열에 의한 유동빙의 융해열전달)

  • 김명환;김경근
    • Journal of Advanced Marine Engineering and Technology
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    • v.19 no.1
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    • pp.36-44
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    • 1995
  • Melting characteristics of unrestrained liquid ice in a rectangular vessel with heated top wall were investigated experimentally. The liquid ice, a mixture of ice particles and ethylene-glycol aqueous solution, was adopted as a testing material. During the melting process the liquid ice was drawn by buoyancy to the heated top wall of the rectangular vessel where close-contact melting occured. The melting behavior and melting rate of the liquid ice as well as local/mean heat-transfer coefficient at the heated top wall were observed and measured under a variety of conditions of heat flux and various initial concentration of the aqueous binary solution. It was found that the heat transfer of the heated top wall is remarkably promoted by the close-contact melting, and that the dendritic frozen layer at the lower interface of the liquid ice is formed. Photographic evidence demonstrated that plumes containing solute-rich liquid issued from isolated chimneys within the liquid ice layer where segregation of interstitial channel took place.

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