2017 Volume 79 Issue 2 Pages 186-196
We developed a prototype of a heated air (HA) recirculation type dryer to dry forage rice economically and efficiently. In this dryer, we replaced a kerosene burner of standard performance with one having superior performance to generate HA at a higher temperature than that commercially available. We conducted experiments to verify the suitability of the developed dryer. We set the average temperature of 60°C, 70°C, 80°C, 90°C, and 100°C. We also set the standard drying mode of a commercially available recirculation type dryer (HA was at 40°C) as a control. When the HA temperature was raised above 60°Cin our prototype, the drying rate increased by about two to four times, and the energy consumption per kilogram of evaporated water decreased by approximately 10% to 25%. Additionally, raising the HA temperature above 60°Cretained the feeding value (nutritional quality) and indicated the possibility of improving the pepsin digestibility. Furthermore, with the increase in HA temperature, the reduction of the drying cost per kilogram of evaporated water varied from 1.6JPY (HA was at 60°C) to 4.6JPY (HA was at 100°C).
We found the raising the average temperature of the HA above 80°Cwas very effective in drying forage rice economically and efficiently. However, examining the operating system of our prototype against the moisture content of dried forage rice that fell below the standard moisture content (14.5%w.b.) was necessary.
