Suitable thin layer drying model for pneumatic paddy dryer

Abstract

The objective of this research was to select a suitable thin layer drying model for a Pneumatic paddy dryer. In the experiment, Khao Dok Mali 105 rice, with a quantity of 20 kilograms and an initial moisture content of 26 percent (wet basis), was used as the sample. Set the drying air velocity to 8.5 meters per second and the motor speed to help drive the rice was constant at 50 revolution per minute throughout the test. The paddy drying process is categorized into three different drying air temperature conditions: 60, 80 and 100 degrees Celsius, respectively. The study found that the Midilli et al. model was the most suitable for predicting the moisture ratio of rice at a drying air temperature of 70 degrees Celsius, compared to other empirical models. It had R² of 0.999, RMSE of 0.0072, and χ² value of 0.000062. The Wang and Singh model proved to be the most appropriate for predicting moisture ratio at a drying air temperature of 80 degrees Celsius, with R² of 0.999, RMSE of 0.0054, and χ² value of 0.000033. Lastly, the Verma et al. model was found suitable for predicting moisture ratio at a drying air temperature of 100 degrees Celsius, with R² of 0.999, RMSE of 0.0052, and χ² value of 0.000038. When these models were further refined for predicting drying behavior within the temperature range of 60 to 100 degrees Celsius, it was observed that the Midilli et al. model provided the highest precision in predicting rice moisture content during the drying process, with R² of 0.999, RMSE of 0.0066, and χ² value of 0.000047, respectively. The obtained model can be used to study the prediction of paddy moisture content during the drying process for planning the operation and energy management of dryers in the future.