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Presented here is a protocol that guarantees uniform distribution of initial moisture inside of a fabric and investigates the effects of hot-air thermodynamic parameters (velocity, temperature, and direction) and thickness on the fabric's drying characteristics (e.g., temperature variation) under the condition of air impingement.
Impinging dryness is now a widely used and effective way for fabric drying due to its high heat and mass transfer coefficient. Previous studies on fabric drying have neglected the contributions of moisture uniformity and diffusion coefficient to the drying process; though, they have recently been shown to have a significant influence on drying characteristics. This report outlines a step-by-step procedure to investigate the effects of air impingement parameters on a fabric's drying characteristics by controlling the uniformity of its area moisture distribution. A hot air blower unit equipped with an angle adjustable nozzle is used to generate air flow with different velocities and temperatures while the drying process is recorded and analyzed using an infrared thermograph. In addition, a uniform padder is adapted to ensure the fabric's moisture uniformity. Impinging drying is studied under different initial conditions by changing the air flow temperature, velocity, and direction, then the applicability and suitability of the protocol are evaluated.
Impinging drying is a very effective drying method due to its high heat, mass transfer coefficient, and short drying time. It has attracted extensive attention due to its numerous applications including chemical industry, food1, textile, dyeing2, paper making3,4, etc. Now, impinging drying is widely used for its enhanced transport characteristics, especially for the drying of textiles in the heat setting process5.
Fabric is impinging dried by the nozzle array for the heat setting. Nozzle layout affects the uniformity of drying temperature, which has a significant influence on the fabric properties, drying efficiency, and on the fabric surface directly. Thus, it is necessary to understand temperature distribution on the textile surface to design a better nozzle array. There has been little investigation in this field at the present, though there has been plenty of research on heat and moisture transfer performance of the fabric drying process so far. Some research has mainly focused on the natural evaporation of a textile under a specified heat source, in which the impinging drying process was not involved in these studies6,7. Some have focused on heat and moisture transfer of the textile with hot air drying, but the textile moisture and temperature were assumed to be uniform in these studies8,9,10,11. Furthermore, a few of these studies attempted to obtain the temperature distribution variation with time for studying the heat and moisture transfer of the textile under impinging drying.
Etemoglu et al.2 developed an experimental set-up for obtaining temperature variation with the time of the fabric and total drying time, but this set-up is limited to single-point temperature measurements. The initial moisture content distribution in the fabric is also neglected in this type of research. Wang et al.12 intended to obtain temperature distribution on the fabric by pasting thermocouples on the textile surface at various points, but surface temperature distribution was not able to be accurately obtained with their method. Obtaining temperature distribution at the air impingement area on a fabric with even humidity distribution is important for industrial printing and dyeing production, and it will provide better guidance on the distribution and arrangement strategy for object drying with a multi-nozzle13. The following procedure provides details to study the heat and moisture transfer of a fabric during the impinging drying process. The initial moisture content is well-controlled to be evenly distributed, while the surface temperature at every point of the fabric is obtained via the experimental set-up.
The experimental set-up consists of a hot air blower unit, infrared thermograph unit, uniform padder system, and other auxiliary devices. The hot air blower unit supplies the hot air with a specified temperature and velocity in an adjustable direction according to the experimental requirements. The infrared thermograph unit records the temperature history of each impinging drying process; thus, the temperature at each pixel point of the recorded video can be extracted with a supporting post-processing tool. The uniform padder system controls the even distribution of moisture content at every point of the fabric. Finally, the influence of air impingement parameters on fabric drying characteristic with fabric moisture uniform control method are investigated. The process can be carried out in a reproducible fashion following the standard protocol described below.
1. Experimental rig set-up
NOTE: See Figure 1.
2. Testing specimen and the manufacturing process
3. Data acquisition, post-processing, and analysis
The data presented in Figure 2 are typical temperature contours for cotton fabric at different drying stages under the condition that air velocity and temperature at the nozzle outlet are 20.0 m/s and 120 °C, respectively. It can be figured from Figure 2A,B,C,D that under the air impingement drying, temperature decays from the center to the periphery and forms sets of concentric circles. Meanwhile, temperatu...
This section provides a few tips necessary to ensure reliable quantitative results. First, the fabric specimens must be kept completely dry to ensure the initial weights are correct. This is achievable through the drying process (i.e., using a suitable drying stove). If possible, an environment humidity that is kept constant benefits the experiment.
Secondly, the fabric specimens must be well-processed to ensure that the moisture at each region of the fabric is uniform. This can be done by man...
The authors have nothing to disclose.
This work was supported by the NSFC-Zhejiang Joint Fund for the Integration of Industrialization and Informatization (grant number U1609205) and National Natural Science Foundation of China (grant number 51605443), the Key Research and Development Project of Zhejiang Province (grant number 2018C01027), the 521 Talent Project of Zhejiang Sci-Tech University, and the Young Researchers Foundation of Zhejiang Provincial Top Key Academic Discipline of Mechanical Engineering of Zhejiang Sci-tech University (grant number ZSTUME02B13).
Name | Company | Catalog Number | Comments |
Air Blower | Zhejiang jiaxing hanglin electromechanical equipment co., Ltd. | HLJT-3380-TX10A-0.55 | Air Volume: 900 m3/s; |
Anemometer | KIMO | MP210 | Measurement range: 0-40 m/s; Accuracy: ±0.1 m/s |
Drying stove | Shanghai Shangyi Instrument Equipment Co., Ltd. | DHG 101-0A | precision: 1 °C; Temperature control range:10-300 °C |
Electronic Balance | Hangzhou Wante Weighing Instrument Co., Ltd. | WT1002 | Precision: 1 °C; Range: 100 g |
Fabric Style Measuring Instrument | SDL Atlas | M293 | |
Fabric Touch Tester | SDLATLAS Ltd | Fabric thickness tester | |
High thermal resistance board | Baiqiang | Flame resistance, Heat resistance is greater than 200 °C | |
High-temperature resistant silicon pipeline | Kamoer | 18# | Temperature range: -60-200 °C |
Infrared Thermogragh | Hangzhou Meisheng Infrared Optoelectronic Technology Co., Ltd. | R60-1009 | Temperature measuring range: -20-410 °C; Maximum measuring error: ±2 °C |
Padder | Yabo textile machinery co., Ltd. | Roller pressure: 0.03-0.8 MPa; Stable pressure; Easy adjustment | |
Personal Computer | Lenovo Group. | L460 | |
Temperature Sensor | Taiwan TES electronic industry co., Ltd. | 1311A | resolution: 1 °C; Temperature measuring range: -50-1350 °C |
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