A Study of Energy Consumption and Drying Rate: Comparison of Continuous and Intermittent Drying Methods of Rough Rice

Rice is one of the oldest-cultivated plants in the world. In terms of cultivated land, it occupies the second largest area after wheat. One of the most critical challenges to meet human demand in the rice production industry is to produce and process this product with the least energy consumption in the shortest duration and with the highest quality. Drying accounts for about 20%-25% of the total energy used in the processing of this product. It has a considerable impact on the final product quality. In this study, we intend to compare continuous and intermittent drying methods of paddy in terms of energy consumption and drying rate. The experiments were conducted using Hashemi rice variety. The drying experiments were conducted at 4 drying temperatures of 40, 50, 60, and 70°C via continuous, two-stage intermittent drying, and three-stage intermittent drying methods. Energy consumption, total drying duration, and process duration were measured for each drying test. The results showed that applying tempering operation between drying stages significantly reduced the energy consumption and the total drying duration. Three-step drying at a temperature of 60°C led to the lowest amount of energy consumption (2566 kJ) and the total drying duration (40 min).