The Mathematical Analysis of the Drying of Cassava Grater by Using Pneumantic (flash) Dryer with Heat Recirculation Method

Abstract

The abundance of cassava cultivation production in Indonesia needs to be balanced with the use of cassava itself to be a source of alternative food as rice subtitute. In this research was done the drying of tubers grater which was cassava to be dried into flour. This drying used a mechanical dryer which was a pneumatic (flash) dryer by using the heat recirculation method (the heat produced from drying was reused). The drying in this research was carried out with a variation of 2 air openings, which were openings for air speed (blower) and openings in the heat recirculation pipe. For openings in the blower, this research used 2 variations of openings, which were openings 50% (air speed 0.0603 m/s) and openings 75% (air speed 0.0768 m/s). For openings in the recirculation pipe, 4 variations of openings were used, which were openings 0% (without recirculated the heat), openings 25% (the heat returned was only 25%), 50% and 75%. The drying time was based on how long the material was in the duct drying. The results showed that, by doing heat recirculation, the value of heating and drying efficiency would increase. The drying in air recirculation 25% could increase the value of drying efficiency for about 5-6%, while in air recirculation 50% could increase the efficiency value for about 3-4%. The value of the heating efficiency of this research ranged from 57-86%. The drying rate constant of the cassava grater moisture content ranged between 0.16 to 0.194%/second.