Moisture transfer measurement

The measurements first reveal an increase in the water level, which can be attributed to moisture transfer from the stopper into the product. The decrease observed subsequently could be due to water expulsion as a result of some product transformation (crystallization of sugar within the substrate, for example). The water would then be adsorbed by the stopper. As a matter of fact, it is well known that the capacity of stoppers to adsorb water depends on their composition [13-15]. Finally, in the third stage, transfer by diffusion through the stopper could account for the slow moisture recovery in each sample. 

It is a well-documented fact that changes in reaction rate correlates well to changes in a, with references too numerous to include. Because reactions alter their behavior as a function of researchers often mistakenly redefine either as (1) a measure of the ability of water to participate in reactions, (2) a ratio of the amount of water that participates in chemical reactions and microbial growth to water that cannot participate, or (3) a ratio of "free" to "bound" water. The actual role of a in food reactions, microbial growth, and moisture transfer has been extensively documented and reviewed but not completely understood (Labuza, 1980 Rockland and Nishi, 1980 Chirife and Buera, 1994). 

In this study, bulky nano Her mats were produced by using a modiHd electrospinning method. Bulk porosify of nano Her mats was measured and the effect of bulk porosity on the air permeability and moisture transfer of nano Her mats was evaluated. 

FIGURES Schematic design of the insttument for measurement of moisture transfer. 

Kusuda has provided very accurate values for properties of moist air, required for measuring the capacity of air-conditioning apparatus, moisture transfer analysis in cold storage machines, and problems concerned with the simultaneous transfer of heat and moisture. 

The intrinsic water vapour resistance (Ret) of fabrics were measured by using standard Sweating Guarded Hot Plate (SGHP) method (ISO 11092 and ASTM FI 868) to simulate the moisture transfer through fabrics when skin is wet and sweating (skin model). 

The term water vapor permeability (WVP, g.m . day ) is commonly used to measure the breathability of the fabric, which indicates the moisture transfer resistanee in the heat and mass transfer processes. This property can be obtained by the experimental measurement with the Evaporation... 

In the study a mathematical model was developed to calculate the values of heat and moisture transfer through the porous textiles applied with PCMs. These values were compared with the porous textiles without PCMs [7]. The distribution of temperatme, liquid water content and moisture concentration were numerically computed on the basis of a finite volume difference model. To validate the mathematical model, the surface temperature of the fabric with PCM was measured by a series of experiments. The diameters of the microeapsules were assumed to be identical and they were embedded in the porous textile structure. The mechanies of coupled heat and moisture transfer and thermal regulation by the PCM were discussed by considering the phase change proeess as a moving boundary problem... 

For the air—water system, the humidity is easily measured by using a wet-bulb thermometer. Air passing the wet wick surrounding the thermometer bulb causes evaporation of moisture from the wick. The balance between heat transfer to the wick and energy requited by the latent heat of the mass transfer from the wick gives, at steady state,... 

Mass Transfer and Useful Capacity. The term useful capacity, also referred to earlier as breakthrough capacity, differs from the equihbrium capacity shown on Figures 9a and 9b. The useful capacity is a measure of the total moisture taken up by a packed bed of adsorbent at the point where moisture begins to appear in the effluent. Thus the drying process cycle must be stopped before the adsorbent is fully saturated. The portion of the bed that is not saturated to an equihbrium level is called the mass-transfer 2one. 

E. Bouveresse, D.L. Massart and P. Dardenne, Calibration transfer across near-infrared spectroscopic instruments using Shenk s algorithm effects of different standardisation samples. Anal. Chim. Acta, 297, 405 16 (1994). B.G. Osborne and T. Feam, Collaborative evaluation of universal cahbrations for the measurement of protein and moisture in flour by near-infrared reflectance, /. Food TechnoL, 18, 453 60 (1983). 

The BioView sensor (DELTA Light Optics, Denmark) was developed especially for industrial applications. It is capable of completely automatic optical measurement for monitoring and control of different bioprocesses. The instrument is conceived to withstand harsh industrial environments (e.g., high temperature, moisture) and electromagnetic interference. For data transfer a single-fiber asynchronous modem is used, which allows a distance between the computer and spectrometer of up to several hundred meters. 

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