Energy and Exergy Analyses of Rice Drying in a Novel Electric Stationary Bed Grain-Drying System with Internal Circulation of the Drying Medium

In our study, we developed a system to reduce both energy consumption and pollutant discharge during the drying process. We present a new technology, a stationary bed grain-drying test device based on the internal circulation of the drying medium (ICODM). A rice-drying experiment was carried out inside of it, and the influences of air temperature (AT) and air velocity (AV) on the energy and exergy efficiencies (EEE) as well as the improvement potential rate (IPR) and the sustainability index (SI) of the rice-drying process were studied. The following conclusions were obtained: when the rice was dried at a temperature of below 55 degrees C and an AV across the grain layer of 0.5 m/s, the average EEE during the drying process was 48.27-72.17% and 40.27-71.07%, respectively, demonstrating an increasing trend as the drying medium temperature increased. When the rice was dried using an AV across the grain layer in the range of 0.33-0.5 m/s and a temperature of 40 degrees C, the two values were 39.79-73.9% and 49.66-71.04%, respectively, demonstrating a decreasing trend as the drying medium flow velocity increased. IPR and SI were 4.1-8.5 J/s and 1.9-2.7, respectively, at a drying temperature of 30-55 degrees C and an AV of 0.33-0.5 m/s. These conclusions can provide helpful guidance for the optimization and control of the rice-drying process in terms of saving energy.

Automated summary

In this study, a system was developed to reduce energy consumption and pollutant discharge during the drying process. A new technology called the internal circulation of the drying medium (ICODM) was used to conduct a rice-drying experiment. The effect of air temperature and air velocity on energy and exergy efficiencies, as well as improvement potential rate and sustainability index of the rice-drying process were investigated. The findings suggest that controlling temperature and airflow can improve the energy efficiency of the drying process.