Dynamic moisture transfer

Hong K, Hollies NRS, Spivak SM. Dynamic moisture vapour transfer through textiles part I clothing hygrometry and the influence of fiber type. Text Res J 1988 58 697. 

The mechanism of contact-sorption drying is very complex because moisture transfer takes place in heterogeneous and multicomponent systems and is accompanied by thermal effects. The idealized scheme of contact-sorption drying shown in Figure 12.1 reflects phenomena taking place in a dynamic system (e.g., mixing or fluidization), where interaction between the sorbent-material, material-material, and sorbent-sorbent is likely to occur. 

Szczesniak, A.S., Loh, J. and Mannell, W.R. (1983) Effect of moisture transfer on dynamic viscoelastic parameters of wheat flour/water systems, /. RheoL, 27, 537-56. 

Hong K, Hollies N R S and Spivak S M, Dynamic moisture vapor transfer through textiles. Part I Clothing hygrometry and the influence of fibre type . Textile Res. J., 1988, 58, 697-706. 

Hong,K. HoUies,N. R. S. Spivak, S. M. Dynamic Moisture Vapor Transfer Through Textiles, Part I Clothing Hygrometry and the Influence of Fiber Type, Textile Res. J. 1988,58(12), 697-706. 

Fan and Luo [12] incorporated the new two-stage moisture sorption/ desorption model of fibers into the dynamic heat and moisture transfer model for porous clothing assemblies. They considered the radiation heat transfer and the efFect of water content of fibers on the thermal conductivity of fiber material. Further, Fan and his co-woricers improved the model by introducing moisture bulk flow, which was caused by the vapor-pressure gradients and supersaturation state [12]. This improvement made up for the ignorance of liquid water diffusion in the porous textile material in previous models. The equations of the model are listed as follows ... 

To understand the heat and moisture flow characteristics of textile fabrics, many mathematical models have been propounded. Matty computational tools like Computational Fluid Dynamics (CFD), artificial neural networks, fuzzy logic and many more are also being used to understand the complex relationships between the clothing parameters and the perception of comfort. This chapter deals with the studies on heat and mass transfer properties of textile assemblies. The phenomena covered here are diy steady state heat transfer, transient heat transfer, moisture vapor and liquid moisture transfer and coupled heat and moisture transfer properties of fibers, fiber bundles, fibrous materials and other textile stmctures. The processes involved in each and the woik done on modeling and simulation of the transfer processes till date, from the point of view of clothing comfort have been discussed. 

Moisture-transport simulation includes transport as well as storage phenomena, quite similar to the thermal dynamic analysis, where heat transfer and heat storage in the building elements are modeled. The moisture content in the building construction can influence the thermal behavior, because material properties like conductance or specific heat depend on moisture content. In thermal building-dynamics simulation codes, however, these... 

The 2,2,6,6-tetramethylpiperidinoxyl (TEMPO) radical was first prepared in 1960 by Lebedev and Kazarnovskii by oxidation of its piperidine precursor. TEMPO is a highly persistent radical, resistant to air and moisture, which is stabilized primarily by the steric hindrance of the NO-bond. Paramagnetic TEMPO radicals can be used as powerful spin probes for investigating the structure and dynamics of biopolymers such as proteins, DNA, and synthetic polymers by ESR spectroscopy [7]. A versatile redox chemistry has been reported for TEMPO radicals. The radical species can be transformed by two-electron reduction into the respective hydroxyl-amine or by two-electron oxidation into the oxoammonium salt [8]. One-electron oxidations involving oxoammonium salts have also been postulated [9]. The TEMPO radical is usually employed under phase-transfer conditions with, e.g., sodium hypochlorite as activating oxidant in the aqueous phase. In oxidations of primary alcohols carboxylic acids are often formed by over-oxidation, in addition to the de-... 

The critical moisture content depends upon the ease of moisture movement through the solid, and hence, upon the pore structure of the solid, sample thickness and (hying rate. Segment BC is the constant-rate peri(xl. During this pericxl, the drying is controlled simultaneously by heat and mass transfer applied to a liquid-gas interface in dynamic equilibrium with a bulk gas phase. 

Both moisture and solute transport in soils are dynamic processes, and difficult to describe analytically. Further, the processes strongly interact to affect the distribution of contaminants in the soil. Experiments regarding transfer of actinides, or any other material through porous media must therefore include an understanding and control of both processes. 

Clearly, the equilibration of the carbon atoms is due to rapid intermo-lecular silyl transfer. Of course, these results do not rule out a simultaneously occurring slow dyotropic process. The nature of the intermolecular mechanism is uncertain. Compound 43 is highly hygroscopic. Trace impurities such as moisture may cause rapid desilylation, resilylation setting in at different oxygen atom. However, addition of catalytic amounts of water or squaric acid itself has no influence on the reaction rate 62). Alternatively, desilylation may proceed according to Scheme 5. Unfortunately, studies of rate dependency on concentration are not possible for dynamic C—NMR at present. 

This work is part of the smart enterprise division in Tumut Visy Pulp and Paper, and addresses the advanced control and operation of the mill. In this context, a robust dynamic model is developed for the recovery boiler, and validated over a wide range of operating conditions. In the steady state case, energy and mass balances were carried out over the different sections of the process. In the dynamic case, initially, heat and mass transfer across the bed are coupled with moisture evaporation, black liquor pyrolysis, char combustion and gasification, gas-phase. The influence of model parameters kinetic constants and operational variables on process dynamics are studied by numerical simulation. The model was developed/implemented in a Visual C++ environment. 

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