The influence of mechanical action on felting shrinkage of wool fabric in the tumble dryer

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Felting shrinkage of untreated wool fabric occurs easily during tumble drying. Mechanical action applied on fabrics plays a significant part in felting shrinkage of wool fabric. In general, the more severe the mechanical action of a washing or drying machine, the more rapid is felting shrinkage. However, both the degree of mechanical action applied on fabric and the type of mechanical action could influence felting shrinkage of untreated wool fabric. In the current study, fabric movement and felting shrinkage of untreated wool fabric at different rotation speeds of the drum in a tumble dryer under no heating condition were studied. Based on the different fabric movements at different rotation speeds of the tumble drum, the extent of impact force and rubbing force at different rotation speeds were assessed through their ranking. The total mechanical action applied on the fabric was expressed by the percentage of thread removal of “thread removal fabric” during drying process. The results showed that lowest mechanical force on fabrics could be achieved when the higher rotation speed of the drum was used for drying wool fabrics in tumble dryers, and it could prevent wool felting shrinkage. It was also found that falling of the fabric followed by impact to the drum wall caused less felting shrinkage than sliding with rubbing between fabrics. Therefore, falling movement of fabric could be a potential method to dry wool fabric in drying machines without causing severe felting shrinkage

Global Steady Subsonic Flows through Infinitely Long Nozzles for the Full Euler Equations

We are concerned with global steady subsonic flows through general infinitely long nozzles for the full Euler equations. The problem is formulated as a boundary value problem in the unbounded domain for a nonlinear elliptic equation of second order in terms of the stream function. It is established that, when the oscillation of the entropy and Bernoulli functions at the upstream is sufficiently small in $C^{1,1}$ and the mass flux is in a suitable regime, there exists a unique global subsonic solution in a suitable class of general nozzles. The assumptions are required to prevent from the occurrence of supersonic bubbles inside the nozzles. The asymptotic behavior of subsonic flows at the downstream and upstream, as well as the critical mass flux, have been clarified.Comment: 32 pages, 1 figure. arXiv admin note: text overlap with arXiv:0907.3276 by other author

Dimensional change of wool fabrics in the process of a tumble-drying cycle

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Currently domestic tumble dryers are popularly used for drying garments; however, excessive drying and the inappropriate way of tumble agitation could waste energy and cause damage to or the dimensional change of garments. Shrinkage of wool fabrics during tumble drying causes a serious problem for wool garments. The current study investigated the shrinkage of untreated and Chlorine-Hercosett–finished wool fabrics at different drying times. Temperature of air in the tumble dryer, temperature of fabric, moisture content of fabric, and dimensional change at different drying times were measured. For the duration of the tumble drying, the rise of fabric temperature and the reduction of moisture content on the wool fabric were investigated to explore their relationship to the shrinkage of wool fabrics in the tumble-drying cycle. It was found that the tumble-drying process can be divided into different stages according to the temperature change trend of wool fabrics. The shrinkage mechanisms of the untreated and the treated fabrics were different. The dimensional change of untreated wool fabric was caused mainly by felting shrinkage during tumble drying. Chlorine-Hercosett–finished wool fabric can withstand the tumble-drying process without noticeable felting shrinkage due to the surface modification and resin coating of surface scales of wool fibers. The finding from the current research provides further understanding of the shrinkage behavior of wool fabrics during the tumble-drying process, leading to optimizing operational parameters at specific stages of a tumble-drying cycle

Exergy analysis of porous cotton fabric drying process during the domestic air vented dryer

This study reveals energy and exergy efficiencies of the fabric drying processes during air vented dryer. Exergy models of thedrying processes have been formed and each stage is examined in terms of exergetic parameters. Additionally, parametricstudies, including the exergy destruction rates, exergy efficiencies, and exergy loss ratios of the system and its components,have been investigated under various operating conditions. The results indicate that the exergy efficiency increases with theincrease in drying rate. Heater of dryer is the highest exergy destruction component of the whole dryer and its powersignificantly affects exergy destruction of whole drying process; while fan and motor of driving drum are lower exergydestruction component of dryer. Use of staged heating model of adjusting heater power based on drying period is found to be aneffective method to reduce the exergy destruction rate of dryer and fabric damage caused by over-drying. Specifically, exergyefficiency of dryer can be improved by increasing the heater power during the warm up and the constant rate period, or bydecreasing the drying-power during the falling rate and the blow-air period. The findings are found to be useful to systemdesign and performance optimization of domestic dryer in term of reducing irreversibility of the drying system.

Explosion gravitation field algorithm with dust sampling for unconstrained optimization

This research was funded by the National Natural Science Foundation of China (Nos. 61572227, 61772227, 61702214), the Development Project of Jilin Province of China (Nos 20170101006JC, 20180414012GH, 20170203002GX, 20190201293JC), Zhuhai Premier-Discipline Enhancement Scheme, China (Grant 2015YXXK02) and Guangdong Premier Key-Discipline Enhancement Scheme, China (Grant 2016GDYSZDXK036). This work was also supported by Jilin Provincial Key Laboratory of Big Date Intelligent Computing, China (No. 20180622002JC).Peer reviewedPostprin