Techno-Economic Evaluation of Textile Bobbins Drying Processes

Abstract

Drying of textile bobbins was carried out on two kinds of laboratory-scale dryers; in a cross circulation drying rig, atmospheric pressure heating air is used, while in the through circulation drying apparatus, the heating air is pressurized before the drying process takes place.

In both processes, air was electrically heated; different air temperatures and velocities were used. Inside the bobbin, seven thermocouples were placed, in order to provide temperature data during the drying process.

In through circulation drying, plots of temperature against time indicated the presence of an evaporation front, moving from inside the bobbin to the outside. In cross circulation drying, two moving fronts were observed, one starting from inside the bobbin, another from the outside.

Comparison of the two drying processes shows ‘through circulation’ drying to be much faster (about eight times) than ‘cross circulation’, although the first process needs extra energy for drying air pressurisation.

Experimental results so far indicate temperature to be the most important factor; although the cost to produce higher temperature is higher, drying times are shorter, and these two opposed effects result in an overall economy. However, temperature values are limited by the nature of the material, the limit commonly used in industry being 90°C.