Cocoon Drying in a Mixed-Mode Solar Dryer : The Drying Kinetics, Dryer Performance and Mechanical Properties of Raw Silk

Abstract

The purpose of this research was to study the process of drying cocoon by mixed-mode solar dryer by considering the drying kinetics, performance of the dryer for drying cocoon and mechanical properties of raw silk. The dryer mainly consists of a v-corrugated plate solar collector, drying chamber and a blower was used to force the air throughout the solar collector and the drying chamber. The experiment was done by drying 5 kg of cocoons, with the initial moisture content of 220 %db to the final moisture content of 10 %db. The results from drying kinetics experiment showed that the Midilli Kucuk model was the appropriate model for the prediction of drying process. The moisture diffusion coefficient was 9.54x10-10m  2/s. The performance of dryer showed the collector efficiency, drying efficiency and overall drying efficiency of 37.37%, 12.01% and 8.85%, respectively. Also, the experiment of reeling showed that the reelability percentage of dried cocoons were more than that of fresh cocoons and the size of raw silk were more than the silk reeling from fresh
cocoon. Besides this, the tenacity and elongation of raw silk from dry cocoon were more than that of raw silk that from fresh cocoon (p<0.05). Therefore, the mixed-mode solar dryer was found as one of the alternatives for cocoon drying.