Study of in-store drying of rough rice (3rd phase) energy consumption, grain quality and mathematical model improvement

Experiments to study the quality of paddy both in percent head rice and percent germination were done, and found that the specific final energy consumption (excluding losses) for drying with low air flow rate (strategies 1, 2 and 3) was lower than that used by drying with high air flow rate (strategies 4 and 5). But it would be higher or lower when it was considered in terms of primary energy consumption. Comparing among the three strategies of drying with low air flow rate (strategies 1, 2 and 3), the specific final energy consumption of the 3rd strategy was minimum and that of the 2rd strategy was slightly higher than that of the 1st strategy. When the primary energy consumption was considered, the 2nd and 3rd strategies consumed lowest specific primary energy. For drying with high air flow rate, the specific final energy and specific primary energy consumption of the 5th strategy was lower than that of the 4th strategy. If types of energy were considered, the 2nd and 5th strategies could be of the most interest because energy in forms of heat, which was cheaper than electricity for driving fan, was significantly contributed in these strategies. Thus the cost of drying would be lowest. The 3rd strategy was also interesting because of low specific primary energy consumption. The experimental results and those obtained from Soponronnarit (1986)'s near-equilibrium drying model were compared. They are slightly different. In case of drying with low air temperature and low air flow rate, the predicted moisture content was slightly higher than the experimental one, the difference became smaller when the effect of heat from respiration was included in the model. On the contrary, for drying with high air flow rate and high temperature, the predicted moisture content was slightly lower than the experimental one and the effect of heat from respiration is negligible.