Evaluating the dynamic characteristics and energetic performance of a paddy multistage counter-flow dryer

Abstract

Paddy drying is a spontaneous dehydration process following the principles of high product quality, high drying efficiency, low energy consumption, and environmental protection. However, its complex properties hinder the development of optimal control during drying. In this study, the real-time paddy drying state of a paddy multistage counter-flow dryer is simulated utilising numerical simulation technology. Results indicate the simulation results agreed well with the experimental data with mean relative deviation of less than 15%. Moreover, the steady and transient characteristics of present dryer are analysed under multiple disturbances. In addition, the effects of ambient and ventilation parameters on productivity, specific energy consumption, heat loss, and exergy loss characteristics are investigated in detail. Based on the simulation and analysis, a uniform design experiment is performed to determine the optimal ventilation parameters of paddy with initial moisture content of 0.238 g water g −1 wet matter when ambient temperature and relative humidity are 20 °C and 50%, respectively. Drying air temperatures of 60 °C and 40 °C, and flow velocity of 1600 m h −1 and 1150 m h −1 , respectively, in the high- and low-temperature drying stages are found to be the optimal ventilation parameters. • Captured the steady and transient characteristics of paddy multistage counter-flow dryer. • Analysed the energetic performance under different ambient and ventilation parameters. • Proposed an optimal ventilation strategy considering productivity and energy consumption.