• Title/Summary/Keyword: Water vapor

Search Result 1,640, Processing Time 0.029 seconds

Behavior of Water Vapor Permeability on Layered System

  • Oh, Ae-Gyeong
    • Fashion & Textile Research Journal
    • /
    • v.11 no.2
    • /
    • pp.359-362
    • /
    • 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.

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

  • Rhim, Jong-Whan
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
    • /
    • v.5 no.1
    • /
    • pp.37-46
    • /
    • 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.

  • PDF

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
    • /
    • v.38 no.4
    • /
    • pp.339-345
    • /
    • 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.

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
    • /
    • v.22 no.1
    • /
    • pp.72-79
    • /
    • 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.

  • PDF

Performance of the Geothermal Heat Pump using Vapor Injection for Hot Water (증기분사를 적용한 고온수용 지열 히트펌프의 성능특성)

  • Park, Yong-Jung;Park, Byung-Duck
    • Transactions of the Korean hydrogen and new energy society
    • /
    • v.25 no.3
    • /
    • pp.297-304
    • /
    • 2014
  • The purpose of this study is to evaluate the experimental performance characteristics of a water-to-water geothermal heat pump featuring a vapor refrigerant injection for the production of hot water. The performance of geothermal heat pump with a vapor injection was evaluated by comparing with that of a conventional geothermal heat pump without a vapor injection. For heating operation, the geothermal heat pump with a vapor injection is superior in COP and heating capacity. The vapor injection was more effective for supplying hot water while overloading. The vapor injection was effective for the improvement of the cooling capacity. However, the vapor injection was not effective for the increasing of COP according to the increased input of a compressor. The advantage of vapor injection in water-to-water geothermal heat pump become disappeared while cooling operation with lower part loading.

Water - Assisted Efficient Growth of Multi-walled Carbon Nanotubes by Thermal Chemical Vapor Deposition

  • Choi, In-Sung;Jeon, Hong-Jun;Kim, Young-Rae;Lee, Nae-Sung
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
    • /
    • 2009.06a
    • /
    • pp.418-418
    • /
    • 2009
  • Vertically aligned arrays of multi-walled carbon nanotube (MWCNT) on layered Si substrates have been synthesized by water-assisted thermal chemical vapor deposition (CVD). We studied changes in growth by parameters of growth temperature, growth time, rates of gas and annealing time of catalyst. Also, We grew CNTs by adding a little amount of water vapor to enhance the growth of CNTs. $H_2$, Ar, and $C_2H_2$ were used as carrier gas and feedstock, respectively. Before growth, Fe served as catalyst, underneath which AI were coated as an underlayer and a diffusion barrier, respectively, on the Si substrate. The water vapor had a greater effect on the growth of CNTs on a smaller thickness of catalyst. When the water vapor was introduced, the growth of CNTs was enhanced than without water. CNTs grew 1.29 mm for 10 min long by adding the water vapor, while CNTs were 0.73 mm long without water vapor for the same period of time. CNTs grew up to 1.97 mm for 30 min prior to growth termination under adding water vapor. As-grown CNTs were characterized by using scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and Raman spectroscopy.

  • PDF

Kinetics of water vapor adsorption by vacuum-dried jujube powder

  • Lee, Jun Ho;Zuo, Li
    • Food Science and Preservation
    • /
    • v.24 no.4
    • /
    • pp.505-509
    • /
    • 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.

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
    • /
    • v.20 no.2
    • /
    • pp.161-174
    • /
    • 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.

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
    • /
    • v.9 no.3
    • /
    • pp.229-233
    • /
    • 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.

  • PDF

An Experimental Study of the Effects of Water Vapor in Intake Air on Comvustion and knock Characteristics in a Spark Ignition Engine (흡기중 수증기 함량이 스파크 점화기관의 연소 및 노킹에 미치는 영향에 관한 실험적 연구)

  • 이택헌;전광민
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.6 no.1
    • /
    • pp.205-212
    • /
    • 1998
  • In this study, the effects of water vapor in inlet air on combustion efficiency, general performance, knock characteristics and emission gas concentration were investig- ated through the experiments of combustion and vibration analyses, emission gas analysis by changing water vapor quantity in inlet air with temperature and humidity auto control unit. With partial vapor pressure increase, the brake torque at wide open throttle status decreased and the average ignition delay angle increased, IMEP (indicated mean effective pressured using the integral and 3rd derivatives of filtered cylinder pressure as knock intensity, which matched well with the method of frequency power spectrum of block vibration signal. Water vapor in intake air had influence on the spark knock sensitivity. With the increase of water vapor content in intake air NOx emission was decreased and HC emission was increased.

  • PDF