• Title/Summary/Keyword: Water vapor

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Water Vapor Transport Properties of Nonwoven Batting Materials (부직포 충전재의 수분투파성)

  • Kim, Hui-Suk;Na, Mi-Hui;Kim, Eun-Ae
    • Journal of the Korean Society of Clothing and Textiles
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    • v.22 no.1
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    • pp.72-79
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    • 1998
  • Journal of the Korean Society of Clothing and Textiles Vol. 22, No. 1 (1998) p. 72∼79 The purpose of this study was to investigate the effects of geometrical structure and fiber type on the water vapor transport properties of nonwoven batting materials. Two types of fiber were used such as polyester and wool. Correlation between physical properties of nonwovens and water vapor transport rate was analyzed by Pearson Correlation. Steady and dynamic state water vapor transport properties were measured by absorption, evaporation and cobaltots chloride method respectively. The results were as follows: 1) In geometrical structure, thickness of nonwovens was effected on absorption and evaporation rate and air permeability was more influencing factor on water vapor transport rate than porosity. There were no decreasing of water vapor transport rate in hydrophilic fiber at high relative humudity. 2) The hydrophilicity of fiber affected steady and dynamic state water vapor permeabilities and wool nonwoven showed higher water vapor transport rate than polyester at high relative humidity. 3) Thickness showed higher correlation coefficient with water vapor transport rate than other physical properties of nonwovens.

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Measurement of Water Vapor Permeability of Bio-polymer Films (생고분자 필름의 투습도 측정)

  • Rhim, Jong-Whan
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.5 no.1
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    • pp.37-46
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    • 1999
  • Water vapor permeability of films is commonly calculated from the water vapor transmission rate of the film measured using a permeability cup method which is essentially a gravimetric method. This method was originally developed for petroleum based plastic films with low water vapor permeability. In the case of hydrophilic bio-polymer films, the resistance caused by a stagnant air layer, which is developed between the underside of the film mounted on the cup and the surface of the desiccant saturated salt solution or distilled water, can be significant and, if neglected, ran lead to underestimation of water vapor transmission rates. Therefore, it is necessary to correct water vapor transmission rate data to accurately estimate the water vapor permeability of bio-polymer films.

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Applications of Cryogenic Method to Water Vapor Sampling from Ambient Air for Isotopes Analysis (수증기 동위원소 측정을 위한 저온채집법에 대한 연구)

  • Kim, Songyi;Han, Yeongcheol;Hur, Soon-Do;Lee, Jeonghoon
    • Ocean and Polar Research
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    • v.38 no.4
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    • pp.339-345
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    • 2016
  • Stable water vapor isotopes have been utilized as a tracer for studying atmospheric global circulations, climate change and paleoclimate with ice cores. Recently, since laser spectroscopy has been available, water vapor isotopes can be measured more precisely and continuously. Studies of water vapor isotopes have been conducted over the world, but it is the early stage in south Korea. For vapor isotopes study, a cryogenic sampling device for water vapor isotopes has been developed. The cryogenic sampling device consists of the dewar bottle, filled with extremely low temperature material and impinger connected with a vacuum pump. Impinger stays put in the dewar bottle to change the water vapor which passes through the inside of impinger into the solid phase as ice. The fact that water vapor has not sampled completely leads to isotopic fractionation in the impinger. To minimize the isotopic fractionation during sampling water vapor, we have tested the method using a serial connection with two sets of impinger device in the laboratory. We trapped 98.02% of water vapor in the first trap and the isotopic difference of the trapped water vapor between two impinger were about 20‰ and 6‰ for hydrogen and oxygen, respectively. Considering the amount of water vapor trapped in each impinger, the isotopic differences for hydrogen and oxygen were 0.33‰ and 0.06‰, respectively, which is significantly smaller than the precision of isotopic measurements. This work can conclude that there is no significant fractionation during water vapor trapping.

A study on the water vapor permeability velocity of Polypropylene spunbond non-woven fabrics (폴리프로필렌 부직포의 투습속도에 관한 연구)

  • Choi, Jae-Woo;Jun, Byung-Ik
    • Journal of the Korean Society of Industry Convergence
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    • v.9 no.3
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    • pp.229-233
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    • 2006
  • The water vapor permeability of polypropylene spun bond non-woven fabrics were investigated with the water vapor permeability velocity at $20^{\circ}C$, $30^{\circ}C$ and $40^{\circ}C$ by applying the hygroscopic method. At each temperature 50, 65 and 80 %RH conditions were used. The results indicated that the water vapor permeability velocity increased with increasing the water vapor concentration difference between both sides of sample surfaces and it decreased with increasing the number of the piled-up fabrics and the apparent density.

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Formation and Growth of Atmospheric Aerosols by Water Vapor Reactions in an Indoor Smog Chamber (스모그 챔버에서 수분 반응에 의한 대기 에어로졸의 생성 및 성장)

  • Kim Min Cheol;Bae Gwi-Nam;Moon Kil-Choo;Park Ju-Yeoun
    • Journal of Korean Society for Atmospheric Environment
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    • v.20 no.2
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    • pp.161-174
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    • 2004
  • Aerosol formation and growth by water vapor reactions were investigated in a 2.5 -㎥ indoor smog chamber filled with the unfiltered ambient air. The relative humidity of test ambient air was elevated at 59~64% or 84~88% by adding water vapor. The aerosol number size distribution and the concentrations of $O_3$, NO, NO$_2$, and SO$_2$ were measured during the experiments. The $O_3$ and NO$_2$ gases were well reacted with the water vapor at high relative humidity of 84~88%, and the reaction rates of these gases seemed to be decreased at low relative humidity of 59~64%. The formation and condensational growth phenomena of ambient aerosols by water vapor reactions were observed in a Teflon bag, depending strongly on the initial particle size distribution. The water vapor reactions might be affected by the contents of oxidants produced by photochemical reactions under sunlight.

Behavior of Water Vapor Permeability on Layered System

  • Oh, Ae-Gyeong
    • Fashion & Textile Research Journal
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    • v.11 no.2
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    • pp.359-362
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    • 2009
  • This study investigates the behavior of water vapor permeability of a layered system to find out a comfortable combination of a layered system for outdoor activities and examines the water vapor permeability of various types of outdoor clothing fabrics. The layered system includes the base layer such as sportswool and polyester/cotton fabrics, the middle layer such as single and double sided fleece fabrics, and the shell layer such as polyurethane-coated, PTFE-laminated and microfiber fabrics in this experiment. Results show that the layered system was applied, it was working together as a whole having some influence on each other layer, though every layer offered varying degree of water vapor permeability. Water vapor permeability of layered system exactly followed the same trend as the shell layer, which is all vapor permeable water repellent fabrics as a single layer. The rate of water vapor transfer through a layered system is mainly related to the type of vapor permeable water repellent fabrics used for the shell layer.

The Experimental Study on a Effect of Korean Paper (Hanji) on Indoor Humidity Control (한지(韓紙)가 실내습도조절에 미치는 영향에 관한 실험적 연구)

  • 이종원;임정명
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.6
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    • pp.599-607
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    • 2004
  • The purpose of this study is to reevaluate the performance of Hanji as an architectural material. Hanji has good things in controlling indoor space comfortably. Particularly, ability of controlling humidity of Hanji affects indoor space comfort and human health. The major focuses of this experimental research are (1) how much of water vapor passes through Hanji, (2) how much of water vapor is absorbed into Hanji. In the first case, indoor humidity is higher than outdoor humidity. In this case, approximately 38 g of water vapor passes through Hanji 1, genarally utilized in window paper (Changhoji), per square meter in one hour. And approximately 4 g of water vapor is absorbed into Hanji 2, genarally utilized in wallpaper, per square meter. In the second case, outdoor humidity is higher than indoor humidity. In this case, Hanji passes water vapor to inner space at first, but when indoor relative humidity reach approximately 66%, although outdoor humidity is higher than indoor humidity, water vapor doesn't pass through Hanji. If Hanji is utilized in window material and wallpaper, indoor space is maintained comfortably without mechanical devices in humidity control.

Kinetics of water vapor adsorption by vacuum-dried jujube powder

  • Lee, Jun Ho;Zuo, Li
    • Korean Journal of Food Preservation
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    • v.24 no.4
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    • pp.505-509
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    • 2017
  • Water vapor adsorption kinetics of vacuum-dried jujube powder were investigated in temperature and relative humidity ranges of 10 to $40^{\circ}C$ and 32 to 75%, respectively. Water vapor was initially adsorbed rapidly and then reached equilibrium condition slowly. Reaction rate constant for water vapor adsorption of vacuum-dried jujube powder increased with an increase in temperature. The temperature dependency of water activity followed the Clausius-Clapeyron equation. The net isosteric heat of sorption increased with an increase in water activity. Good straight lines were obtained with plotting of $1/(m-m_0)$ vs. 1/t. It was found that water vapor adsorption kinetics of vacuum-dried jujube powder was accurately described by a simple empirical model, and temperature dependency of the reaction rate constant followed the Arrhenius-type equation. The activation energy ranged from 50.90 to 56.00 kJ/mol depending on relative humidity. Arrhenius kinetic parameters ($E_a$ and $k_0$) for water vapor adsorption by vacuum-dried jujube powder showed an effect between the parameters with the isokinetic temperature of 302.51 K. The information on water vapor adsorption kinetics of vacuum-dried jujube powder can be used to establish the optimum condition for storage and processing of jujube.

Studies on Water Vapor Sorption through Hard Gelatin Capsules (경(硬)캅셀제(劑)의 흡습(吸濕)에 관(關)한 연구(硏究))

  • Park, Joung-Hoon
    • Journal of Pharmaceutical Investigation
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    • v.2 no.1
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    • pp.40-51
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    • 1972
  • Water vapor sorption of corn starch in various protective film coated capsules in 100% RH chamber for 14 days were as follows: The percent of water vapor sorption were 28.63% in uncoated capsule, 25.16% in hydroxy propylcellulose(HPC) coated capsule, 15.59% in 2-methyl-5-vinyl pyridine-methyl acrylated-methacrylic acid (MPM) coated capsule and 15.50% in polyvinyl acetal diethyl amino acetate(AEA) coated capsule. 2. Water vapor sorotion of magnesium trisilicate in various protective film coated capsules in 100% RH chamber for 14 days were as follows. The percent of water vapor sorption were 13.91% in uncoated capsule, 13.30% in HPC-coated capsule, 10.87% in MPM-caated capsule and 9.9% in AEA-coated capsule. 3. Water vapor sorption of magnesium carbonate in various protective film coated capsules in 100% RH chamber for 14 days were as follows: The percent of water vapor sorption were 12.48% in uncoated capsule, 10.72% in HPC-coated capsule, 8.10% in MPM coated capsule and 7.8% in AEA-coated capsule. 4. MPM-coated capsules and AEA-canted capsules were mere effective to protect water vapor sorption than HPC-coated capsules.

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Correlation Analysis between GPS Precipitable Water Vapor and Heavy Snowfall on Gangwon Province in Early 2011 (2011년 강원 폭설과 GPS 가강수량의 상관성 분석)

  • Song, Dong-Seob
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.30 no.1
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    • pp.97-104
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    • 2012
  • In this paper, the GPS precipitable water vapor was retrieved by estimating of GPS signal delay in the troposphere during the progress of heavy snowfall on the Gangwon Province, 2011. For this period, the time series analysis between GPS precipitable water vapor and fresh snow depth was accomplished. The time series and the comparison with the GPS precipitable water vapor and the fresh snow depth indicates that the temporal change of two variations is closely related to the progress of the heavy snowfall. Also, the periodicity of GPS precipitable water vapor using the wavelet transform method was showed a similar cycle of saturated water vapor pressure as the limitation of this study span. The result shows that the decrement of GPS precipitable water vapor was conflicted with the increment of fresh snow depth at two sites, Gangneung and Uljin. The correlation between the GPS precipitable water vapor and the saturated water vapor pressure for the event was showed a positive correlation, compare with the non-heavy snowfall periods.