Influences of drying parameters on efficiency rate of paddy rice in deep fixed-bed

In order to reduce drying energy consumption for paddy rice and enhance the production efficiency, a new concept of efficiency rate which showed thermodynamic characters was defined for paddy drying in a deep fixed-bed based on analyzing the existing indexes. A series of paddy drying experiments were conducted in a deep fixed-bed. Influencing laws of each experiment factor on the new index were investigated. Five-factor quadratics rotary orthogonal combination was adopted to establish the relationship between performance function and each factor, and the effects of each factor on the efficiency rate were investigated. An optimum range under 95% probability of efficiency rate lower than 2000 kJ/(kg?h) was obtained as follows: drying air temperature, drying air velocity, paddy thickness, original moisture content and tempering time were 56.2-57.7℃, 0.89-0.96 m/s, 35.3-37.0 cm, 21.31%-21.86%, 2.87-3.16 h, respectively. The results provide a reference for saving energy of paddy drying in the practice and the research of paddy drying process simulation.