The Drying of Chili Spur Pepper by Using a Longan Dryer

Abstract

The biomass longan dryer, which is used in this research, consists mainly of a dual
stage of 40x120x120 cm drying chamber, a combustion chamber, a hot air damper and a ducting
system with air recycling. The chili spur pepper was selected to be a drying product for using
the biomass longan dryer during off-season longan harvesting in order to increase the operating
efficiency as well as to reduce the payback period (PBP) of this type of dryer. Optimal
conditions of chili spur pepper drying in terms of the product layer thickness and the fraction of
air recycling were investigated based on experimentation by considering the drying time,
specific energy consumption and product quality.
Optimal product layer thickness was found to be 20 cm with a product capacity of
200 kg. Drying air temperature was about 80oC and drying time was about 15 hours. Initial
moisture content of 250% (db) reduced to a final moisture content of 13% (db) with the specific
energy consumption of 12.95 MJ/kg H2O evaporated. Experimental results indicated that the
optimal fraction of air recycling should be 80% whereas the drying time was extended to be 17
hours with the specific energy consumption of 10.23 MJ/kg H2O evaporated corresponding to
an energy savings of 21%.

Keywords: chili spur pepper / drying / longan dryer / air recycling / energy saving