2000 Volume 62 Issue 3 Pages 128-139
To determine the drying characteristics of rough rice in a closed circulating air dehumidification system, thin-layer drying experiments excluding the effect of layer depth were conducted at different combinations of drying air temperature and relative humidity (r. h.). For the limited variety Mutsuhomare used in the experiments, drying to 15% w. b. moisture level proceeded with temperature as low as 10°C, provided r. h. was 60%. Average drying rate between drying span increased with temperature rise and r. h. fall, but the effect of temperature increase was more significant. The drying rates, 1.60-2.90%d.b./h, at 40°C and 40 to 60% r. h. were greater than 0.78-1.70%d.b./h at 30°C and 0.45-0.88%d.b./h at 20°C. The rates at 10°C and 50 to 60% r. h., 0.41-0.50%d.b./h, were higher than those of natural drying, 0.31-0.36%d.b./h. At 10°C, the decrease in r. h. did not significantly affect drying rate. The sum of heavily and lightly fissured grain percentages linearly increased as drying rate rose.
