A study on drying of textile substrates and a new concept for the enhancement of drying rate

Abstract

Gravimetric absorption test system (GATS) is used to measure the absorption capacity, absorption rate and drying rate of knit hoses, prepared from different fibres. The fibres studied are cotton, polyester and variety of modified polyesters. The study has shown that desorption or drying rate is at least two orders of magnitude lower than absorption rate. This finding implies that drying is the limiting process in moisture management. Further experiments on knit fabrics made from polyester and cotton, show that the drying rates are independent of fibre type in the constant-rate period, while the drying rates in the falling-rate period are dependent on fibre type. Subsequently, it is shown on the polyester fabric that drying rate in the falling-rate period depends on water concentration. Based on this understanding, an approach for enhancing drying rate in the falling-rate period is defined. The approach is demonstrated on knit hoses prepared from cotton and polyester yarns in alternating stripe form. The drying rate in the falling-rate period is found to be higher in the polyester-cotton stripe knit hose. A hypothesis for the observed enhancement in drying rate by wicking is put forth in terms of the internal movement of water from polyester to cotton portion. Experimentally, it is shown that 16% improvement in drying time is achieved in the case of the polyester-cotton stripe samples. Further, indications of internal water movement from polyester to cotton portion have been obtained by tracking the surface temperatures of the knit hoses during drying by infrared (IR) thermography.

Prediction of the water evaporation rate of wet textile materials in a pre-defined environment

“…Although the fiber type, the thickness and the fabrication of tested materials varied greatly, the evaporation rates did not show a big difference. It is consistent with the previous finding (Steele, 1953;Gurudatt et al, 2010).…”

“…A possible reason for this difference is that evaporation takes place on both sides of a fabric by the suspension method proposed Fourt et al, while evaporation occurs mainly from one side of a specimen in the tests of this study. Gurudatt et al (2010) obtained the drying rate as 7.8~8.5×10 −5 g/s on 100 percent saturation polyester and 8.1~8.7 10 −5 g/s for 100 percent saturation cotton knitted fabrics, respectively. By dividing them by the area of the circular specimens of 5.8 cm diameter (26.4 cm 2 ), the ranges of WER were obtained as 1.77~1.93 g/(m 2 ×min) for polyester and 1.84~1.98 g/(m 2 ×min) for cotton.…”

“…In the gravimetric absorption test system (GATS) used by Gurudatt et al (2010), the samples were wetted to desired levels of water content, in terms of percentage of saturation absorption capacity, and then allowed to dry on the weigh table of the GATS. Drying rate was expressed as weight change rate with a unit of gm/s.…”

The Role of Yarn Counts and Polyester/Cotton Blends in Comfort of Knitted Fabric

“…These findings are also in line with the observations made in previous study that improvement in drying time is achieved in the case of the polyestercotton stripe samples. Further, indications of internal P/C blend ratios water movement from polyester to cotton portion have been obtained by tracking the surface temperatures of the knit hoses during drying (Gurudatt et al, 2010).…”

Analysis and modeling of drying behavior of knitted textile materials

“…Guruddat et al [31] has used cotton and polyester fibres for knitted fabric production and they investigated that during the constant rate period, drying rates of knitted fabrics are independent from fibre type. On the other hand fibre type had been reported to have a significant effect on drying rates in the falling rate period.…”