Development of Hot-Air Supplemented Solar Dryer for White Yam (Dioscorea Rotundata) Slices

Abstract

In this study, a hot-air supplemented solar dryer was designed and fabricated for drying white yam slices Dioscorea rotundata. The capacity of the designed hot-air supplemented solar dryer was 14 kg. The equipment was tested in Federal University of Technology Akure (FUTA) using white yam Dioscorea rotundata to establish the effect of incorporating the hot-air section into the solar dryer. Drying experiments were conducted using a temperature of 60 °C for the hot-air supplemented solar drying process at a drying air velocity of 0.8 m/s. After the experiment, it was deduced that the total drying time used to reduce the moisture in the white yam slices to safe storage moisture content (SSMC) differs for the two different drying conditions giving a total drying time of 18 hours for solar dryer and 13 hours for hot-air supplemented solar dryer. The average dryer thermal efficiency for the solar dryer was 31.45 %, and the average dryer thermal efficiency is 42.10 % at solar/mechanical drying at 60 oC, and also the solar collector highest efficiency was calculated to be 83.28 % at solar radiation intensity of 1199.46 W/m 2 and lowest efficiency of the solar collector was 23.89 % at solar radiation intensity of 300.40 W/m 2 .