Experimental Study and Mathematical Model to Follow the Drying Phenomenon of Knitted Textile Fabric

In this paper, the results of an experimental study on textile thermal drying after wet processing pretreatments are presented. The mass variation of the studied samples as a function of drying time was determined using the gravimetric method at three different temperatures: 100°C, 110°C and 120°C. A polynomial model was found and established to follow the drying phenomenon of wet textile fabric. INTRODUCTION Textile fabrics either as knits or woven have to be cleaned, prepared, dyed, or printed and undergo subsequent finishing after these wet processing treatments. Drying is the stage between wet processing and dry finishing treatments. It is a very important step which aims to free the textile of moisture and to extract water from the material. In industry, it is very important to choose the appropriate instrument and to control the systems for the achievement of uniform drying and avoid its negative effects on quality. Therefore, the study of this phenomenon becomes very important and has attracted the attention of several authors [1-6]. Drying techniques may be classified as mechanical or thermal. Mechanical processes are used in general to remove the water which is mechanically bound to the fiber. This is aimed to improve the efficiency of the following step. Thermal processes consist in heating the water and converting it into steam. The dynamics of drying textile fabric after treatment with foam solutions is studied by M. S. Ivanov et al [7]. The drying curves for fabric and base treated with warp-sizing foam were experimentally obtained and discussed. The experiment was conducted on samples of base and fabric from a blend of natural, synthetic, and man-made fibers. Finally, transfer functions corresponding to transients and reflecting the dynamics of drying for the three drying objects indicated above were determined. They found a welldefined model for each sample. The influence of initial moisture content, drying temperature, and air velocity was observed and studied by Luiza H. C. D. Sousa et al [8]. They used an individual knitted fabric samples (150x150mm) of cotton fiber of approximately 0.60 mm thickness and ambient moisture content ranging from 7 to 10%. They used the equation proposed by Page [9]. But this model was effective where accurate modeling of initial drying behavior was not important. They found that the influence of the three operational variables studied on cellulose drying (initial moisture content, surface temperature, and air velocity) could be analyzed with the generalized drying curve. In the literature, the study of textile drying is limited. However, there are numerous studies of the technique of drying of foods [10-15]. For example, samples of plums were pretreated in alkali solution containing ethyl-oleate and dried in a laboratory dryer at 65 °C and 1.2 m/s air velocity [10]. Doymaz et al [10] have studied the effect of pretreatments on drying plums under hot-air. They found that convective drying of pretreated plums was 29.4% shorter than that for untreated plums. According to these experimental results, they considered two different models. The empirical exponential model (Eq.1) for untreated plums and Eq. 2 for treated plums. ) + ) = t b t a MR 1 0 (-k exp (-k exp (1) 2 1 bt at MR + + = (2) Where: a, b, k0 and k1were an empirical constants in drying models and MR was the moisture ratio. In this paper, because no information is available on the drying behavior of textile fabrics, a mathematical model was developed to follow the drying phenomenon of textile fabric after wet processing