Study on drying characters of a thin cotton fabric under uneven radial heating by the hot air jet

Abstract

It is important to understand the characteristics of hot-air drying of cotton fabrics for the structure design and process optimization of the drying equipment. A transient heat and moisture transfer model of the thin porous cotton fabric is established, in which the uneven heating on the textile surface caused by the hot air jet was considered. The effects of environmental air temperature and relative humidity, initial moisture content, hot air temperature, and velocity at the nozzle outlet on the drying characters were studied via this model. Results show that the temperature of the constant rate drying period at various points on the fabric is different due to the uneven heat input, which is higher at the center part of the fabric and lower away from the center of the fabric. The drying time is very non-uniform on the fabric surface especially when the hot air for drying and the environmental air have a large temperature difference. The environmental air humidity also has great influence on the drying time. The drying time of fabric increases by more than two times as the environmental air humidity rises from 5% to 30%. During the drying process, increasing hot air temperature is more conducive to improve the drying efficiency than increasing hot air velocity. The drying time decreases 19% only when the hot air velocity doubled, meaning that increasing hot air velocity cannot improve drying rate effectively. Moreover, experiments were conducted and results show that the experimental results coincided with the simulated ones well.

Keywords:

• Impingement drying
• moisture content
• heat and mass transfer
• cotton fabric
• mathematical modeling
• porous media

Acknowledgements

The authors would like to acknowledge the supports from [National Natural Science Foundation of China] (number 62173307); [Zhejiang Provincial Public Projects of China] (number LGG18E050022); [Key R&D projects of Science and Technology Department of Zhejiang Province] (number 2019C01027); [the Natural Science Foundation of Zhejiang Province] (number LQ21E050006).

Disclosure statement

The authors declare that there is no conflict of interest with respect to the research, authorship, and/or publication of this article.

Data availability

The data used to support the findings of this study are available from the corresponding author [X Z] upon request.

Additional information

Funding

The authors would like to acknowledge the supports from [National Natural Science Foundation of China] (number 62173307); [Zhejiang Provincial Public Projects of China] (number LGG18E050022); [Key R&D projects of Science and Technology Department of Zhejiang Province] (number 2019C01027); [the Natural Science Foundation of Zhejiang Province] (number LQ21E050006).