Liquid water transmission

BSI (1999). Paints and Varnishes - Coating Materials and Coating Systems for Exterior Masonry and Concrete Part 3 - Determination and Classification of Liquid Water Transmission Rate (permeability) EN 1062-3, British Standards Institute London. 

As mentioned above, heat and mass transfer in textile materials is a complex phenomenon that includes several mechanisms. Textile material properties significantly influence these mechanisms. Several researchers studied the effect of these properties on heat and mass transfers at three different levels (1) the microscopic level (chemical composition, morphological characteristics, fineness, cross-section, porosity, and water content of the component fibers), (2) the mesoscopic level (yam structure and properties), and (3) the macroscopic level (the fabric s physical and stmctural characteristics and finishing treatments) [3,22,23]. Thus, in the following section, heat transfer properties, such as thermal conductivity, thermal resistance, thermal absorptivity, and thermal emissivity and mass transfer properties, such as water vapor transmission and liquid water transmission, will be defined at fiber, yam, and fabric levels. 

A porous structure, which contains voids also called pores, is filled with a fluid (liquid and/or gas). Thus, mass transfer properties of textile materials can be studied at two levels water vapor transmission properties and liquid water transmission properties. 

Goldstein, R., and S. S. Penner, Transmission of Infrared Radiation through Liquid Water and through Water Vapor near Saturation, J. Quant. Spectrosc. Radiat. Transfer, 4, 359-361 (1964). 

All IR measurements were performed by a transmission method. IR spectra through a Cap2 plate without any samples were first measured from 25 to -120°C to clarify how the IR spectra depend on measurement temperatures. The IR spectrum at 25 C was used as a background spectrum k to obtain absorption spectra Ahs = -log(///o)) for all IR measurements. The spectra for the methane hydrate and water-ice films were taken at every 20°C after keeping for 10 minutes at temperatures from -120 to -20 C. An IR spectrum for the liquid water film was performed at 25 C. 

Liquid water and sometimes water vapor are removed from natural gas to prevent corrosion and formation of hydrates in transmission lines and to attain a water dew point requirement of the sales of gas. Many sweetening agents employ an aqueous solution for treating the gas. Therefore dehydrating the natural gas that normally follows the sweetening process involves ... 

Moreover, transport phenomena for the sweat case are much more complicated than the water vapour case because wetting of the surface by liquid water precedes water wetting of the surface by liquid water precedes water vapour transmission. Note that there is an important difference in water absorbing characterizing of wool and cotton, although both fibers have relatively high water vapour absorption rates. Because of the hydrophobic surface... 

A range of membrane processes are used to separate fine particles and colloids, macromolecules such as proteins, low-molecular-weight organics, and dissolved salts. These processes include the pressure-driven liquid-phase processes, microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO), and the thermal processes, pervaporation (PV) and membrane distillation (MD), all of which operate with solvent (usually water) transmission. Processes that are solute transport are electrodialysis (ED) and dialysis (D), as well as applications of PV where the trace species is transmitted. In all of these applications, the conditions in the liquid boundary layer have a strong influence on membrane performance. For example, for the pressure-driven processes, the separation of solutes takes place at the membrane surface where the solvent passes through the membrane and the retained solutes cause the local concentration to increase. Membrane performance is usually compromised by concentration polarization and fouling. This section discusses the process limitations caused by the concentration polarization and the strategies available to limit their impact. 

Mass transmission through textile material takes place both in the form of liquid water and water vapor. The process of moisture transport through clothing imder transient humidity eonditions is an important factor to influence the dynamic comfort of the wearer in practical use. Moisture may transfer through textile materials in vapor and in liquid form, as outlined below. 

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