Development of a novel drying algorithm for reducing dimensional change on cotton textiles during tumble drying

Abstract

With the development of technology, the need for drying machines, which entered our lives, is increasing day by day as people are more involved in working life. People who want to save time and space and want to spend less effort for washing-drying processes are more attracted to this machine. Although the dryer appears to be a useful product in theory, it is a product that people use hesitantly. The main reason for this feeling is that drying machines shrink certain types of textiles, especially cotton-containing textiles. Within the scope of this study, a survey was conducted in order to determine the main source of the problem and to get to know the laundry habits of the users in daily life. According to the results of the survey, the shrinkage problem was determined and a phased experiment plan was designed by procuring fabric samples to simulate the textile products that the users most frequently observed shrinkage in daily life. Drying machines of different brands and models specified in the questionnaire were purchased and detailed algorithm analysis and shrinkage tests were applied. This study was carried out as a preliminary study and as a result, it was seen that there was no obvious difference between the shrinkage rates of the dryers available in the market, and all of them caused shrinkage at similar rates. It has been determined that slow drum rotation and high drum inlet temperature are the parameters that partially affect the shrinkage positively. Then, the test plan was designed considering the user conditions and the ½ Fractional Factorial Design of Experiment (DOE) study was planned. All data obtained as a result of experimental design tests and preliminary study were collected to form a mathematical model. The mathematical model was developed using the R program. By feeding 111 test data directly to the model, it is aimed to predict the shrinkage regardless of the dryer brand and model. The created model can make predictions with an accuracy rate of 97.5%. While creating the mathematical model, the importance and degree of influence of the parameters added to the model were determined and it was determined that the most important parameter affecting the shrinkage was the drum speed and drying time. Before the algorithm was designed, the shrinkage rates of the test samples were measured at different capacities periodically every 20 minutes in order to understand the development of shrinkage in the dryer and its relationship with humidity. By graphing the obtained data, it has been determined that there is a point where shrinkage gives the best results from the beginning of drying. This point is called the "Critical Moisture Point". In the periodic follow-up tests, it was determined that cotton textiles were not affected by any mechanical action and did not show shrinkage until the critical moisture point. On the contrary, it has been determined that when the textile, which comes from the washing machine with a certain amount of shrinkage, is put into the dryer, it releases itself and expands in size until it reaches the critical moisture point. It has been observed that when drying is continued after the critical moisture point, the textile starts to shrink and shrinks until the drying is complete. By combining the findings obtained as a result of all the experiments, an algorithm was designed to reduce the shrinkage rate during tumble drying of cotton textiles. Since the most important criterion in the algorithm design is the drum rotation, various iterations have been made by constructing drum stop and rotation durations at low speed and high speed. The purpose of the design is providing minimum mechanical drum movement. After drying in the 2800 RPM configuration until the critical humidity level, the configuration where the drum is slowed down to 1800 RPM and rotated for 2,5 minutes, then stopped for 7,5 minutes gives the lowest shrinkage rate among all trials. In order to ensure homogeneity and faster drying in the determined algorithm design, the system was supported with an additional heater. In the preliminary studies and as a result of the DOE tests, since the drying time directly affects the shrinkage, the shrinkage rate is further improved with the addition of an additional heater. While the lengthwise shrinkage rate of the reference Cotton Economic program was 9,2% in the knitted test sample and 2,1% in the woven test sample, the lengthwise shrinkage rate was measured as 6,6% in the knitted test sample and 1.6% in the woven test sample after the innovative algorithm design was developed. As a result of the new algorithm design, the lengthwise shrinkage rate has been improved by 28% in knitted textiles and 24% in woven textiles.