PERPINDAHAN MASSA AIR PADA PROSES PENGERINGAN GABAH MENGGUNAKAN MESIN PENGERING TYPE ROTARY

Transfer of Water Mass in The Grain Drying Process Using a Rotary Type Drying Machine. Grain is an agricultural commodity that contains a very high moisture content after harvesting. In general, the water content contained in rice is around 20-23% wet basis in the dry season and in the rainy season it is around 24- 27% wet basis. The main purpose of drying rice grain is to reduce its water content by around 13% -14% which previously grain had 25% moisture content. During the drying process the moisture content or moisture content of the grain experiences evaporation and spreads to dry air. Dry air that previously had low humidity levels will increase during the drying process. This shows that there is a transfer of the water mass of the material to the dry air around it. The use of a rotary drying machine will facilitate the grain drying process. Therefore it is necessary to analyze the process of mass transfer of water in grain to dry air during the drying process. Before the drying process is carried out, a moisture content test is carried out to determine the initial moisture content of the grain so that it can be determined by the mass of water that will be evaporated later. The grain drying process is carried out with a capacity of 5000 gr. Each drying process was carried out with wet bulb temperature 〖(T〗 _wb), dry ball 〖(T〗 _db), and mass (Ma) was observed and recorded. The process of drying grain using a rotary type of pressing machine takes 60 minutes and is compressed. The final moisture content of grain after drying is 14%, previously 25%. The largest decrease in water mass and water content of unhulled rice occurred at the first 20 minutes of drying, while the smallest occurred at the last 20 minutes of drying. The average drying rate of grain is 0.14% with a decrease in water mass of 9.17 grams for every minute of drying. The difference in the value of the humidity ratio between the input and output sides of the drying tub tends to decrease from 20 to 60 minutes, until the end of drying. The relative humidity value during the drying process always decrease