Influence of stitch length and structure on selected mechanical properties of single jersey knitted fabrics with varying cotton percentage in the yarn
Knitting is a process of manufacturing a fabric by the intermeshing of loops of yarn. Knitted fabric possesses high stretch and recovery, providing greater freedom of movement and outstanding comfort qualities for which they have been preferred as fabrics in many kinds of clothing for a long time. In clothing design and manufacturing, fabric characteristics are usually dictated by a specified end-use.1,2
The Effect of Tuck Stitch on the Properties of Weft Knitted Fabric
ABSTRACT The fabric structure is the fundamental unit that controls all properties of weft knitted fabrics. This paper studies the effect of three weft knitted structures; single jersey, rib 1 and 1, and cardigan on various properties. Knitted fabrics from 100% wool yarn of 3.8 Nm on flat knitting machine were used in the study. The effect of knit structure on the dimensional stability, density, resistance to pilling, fabric drape, fabric Diameter, color fastness to washing, and to rubbing properties are investigated, and it was found that tuck stitch influenced the properties of Knitted Fabrics. It increased their areal density, made it more porous, increased their pilling resistance, their drape coefficient, their width and kept their dimensional stability. However, the tuck stitch did not have a major influence on color fastness properties of knitted fabrics.
Effect of superficial gas velocity on the particle temperature distribution in a fluidized bed with heat production
The heat transfer behavior of particles and gas in an olefin polymerization fluidized bed was numerically analyzed using an in-house developed 3-D computational fluid dynamics discrete element model (CFD-DEM). First the implementation of the model was verified by comparing simulation results with analytical results. A constant volumetric heat production rate was implemented in the particle energy equation to mimic the heat production due to the polymerization reaction. It was found that the probability density function (PDF) of the particle temperature becomes more homogeneous with increasing superficial gas velocity. Furthermore, instantaneous snapshots of the thermal driving force (the difference between the single particle temperature and bed-average gas temperature, Tp− ) for different heat production rates provide detailed insight in the particle temperature distribution inside the fluidized bed. The time- and bed-averaged particle convective heat transfer coefficient, which was calculated by Gunn׳s correlation, was found to be independent of the superficial gas velocity. This is explained by the fact that the relative velocity of gas and particles in the emulsion phase, where most of the particles and gas interact, is hardly influenced when increasing the gas superficial velocity. From the spatial distribution of Nusselt number, it becomes apparent that the high heat transfer regions are found in the wake of rising bubbles, whereas low heat transfer rates are found in the clouds of the bubbles.