Numerical investigation of airflow and heat transfer characteristics and optimal design of the American ginseng drying room

Highlights: • A mathematical model is proposed for flow and heat transfer in ginseng drying room. • The inhomogeneities are investigated for the velocity and temperature fields. • The key influence factors are clarified for the inhomogeneity distributions. • The drying room is optimized according to the key influence factors. The airflow and heat transfer characteristics in drying rooms have significant effects on drying behavior and product quality. Therefore, inhomogeneity has been a research hot spot in the drying industry. However, the key factors influencing the inhomogeneities of both velocity and temperature distributions are still not fully revealed. The proposed relevant optimizations are based only on the temperature distribution inhomogeneity, without considering the velocity distribution. Moreover, literature focusing on American ginseng drying is rare. In this study, we performed a numerical simulation and proposed an optimal design for an American ginseng drying room. For this purpose, a mathematical model for the airflow and heat transfer in a ginseng drying room is proposed and validated using experimental data. The inhomogeneity characteristics of the airflow and temperature distributions are investigated, and the optimal parameters for a ginseng drying room are determined based on the inhomogeneity coefficients. The results show that the inhomogeneous distributions of the airflow and temperature in the drying room are mainly influenced by the inlet airflow rate, inlet diameter, and number of partition boards with stacked ginseng. By optimizing the above three parameters, the inhomogeneity coefficients of the airflow and temperature distributions in the American ginseng drying room used in this study can be reduced by 13.67% and 11.76%, respectively. This research not only helps to deepen the understanding of the airflow and heat transfer characteristics and optimize the American ginseng drying room, but also provides useful insights for the investigation and optimization of the conditions in the other drying industries.