Water Vapor

Flexible PVC/silica composite membranes having a porous structure have been produced using plastisol-plastigel technology. Equilibrium and rate studies related to water vapor adsorption on membranes have been studied using a Cahn 2000 gravimetric adsorption system. For the solubility and diffusivity of water vapor in membranes 4.23-7.74 cm3/(cm3 cmHg) and 2.0–3.5 × 10−13 m2/s values have been determined respectively. The measured permeability of water vapor through membranes 1.6–7.3 × 10−6 ((cm2/s)/(cm2 cmHg))cm, were much higher than predicted permeabilities 0.85−2.73 × 10−8 ((cm2/s)/(cm2 cmHg))cm. from solubility diffusion data, indicated the membranes had a porous structure.The membranes are suggested as a leather substitute since the permeability through membranes is comparable to that of leather and is at least 100 times higher than that of plasticized PVC film obtained by conventional processing techniques.

In a joint venture between Agricultural Research Organization, Volcani Center and StePac L.A Ltd. (Tefen, Israel), a series of plastic films have been developed (commercial name Xtend®) with higher permeability to water vapor than most commercially available MAP products. Using hydrophilic Xtend® films manufactured from various proprietary blends of polyamides with other polymeric and non- polymeric compounds allowed achieving in-pack

An atmospheric pressure plasma jet generated in Ar/water vapor mixtures has been investigated and the effect of water content on plasma properties has been studied. Plasma generated in Ar/water (0.05%) mixture shows higher intensity of OH radicals in emission spectra than pure argon alone. Plasma density has been estimated from current measurement and is in order of 1.5×1013 cm-3. Electron temperature has been estimated as 0.97 eV in pure Ar and it decreases with an increase in water content in plasma. The gas temperature has been determined by fitting of the experimental spectra and using the Boltzmann plot method. The gas temperature increases with the addition of water to feed gas from 620 K in pure Ar up to 1130 K for 0.76% H2O.

A diffusion driven desalination process was recently described where a very effective direct contact condenser with a packed bed is used to condense water vapor out of an air/vapor mixture. A laboratory scale direct contact condenser has been fabricated as a twin tower structure with two stages, co-current and countercurrent. Experiments have been operated in each stage with respective saturated