# Design of and Experimental Study on Drying Equipment for _Fritillaria ussuriensis_
## 6 Conclusions  
1. Based on the principle of hot-air drying, a drying device for _Frtiillaria ussuriensis_ with a maximum drying capacity of 15 kg/h was designed. The device adopts a thermal  
Figure 14: Comparison diagram of test and simulation data. circulation structure consisting of inner and outer drying ovens, and the heating chamber is separated from the drying chamber to prevent local overheating. The internal flow field, temperature field, and pressure field of the device were simulated and analyzed by FLUENT simulation, and the structure of the diversion channel and the layout of the trays were optimized accordingly. This enables hot air to uniformly enter the drying chamber through the left diversion channel, flow through _Fritillaria ussuriensis_, and then enter the outer box via the right air outlet, forming a cycle. After optimization, the pressure field and velocity field inside the device are uniformly distributed, and the temperature of each layer stabilizes at 338 K \(\pm\) 2 K within 600 s, which effectively enhances g thermal efficiency and drying uniformity. This addresses the issues of significant temperature fluctuations and inadequate local drying in traditional drying methods. 2. Through hot-air drying tests at 45 \({}^{\circ}\)C, 55 \({}^{\circ}\)C, and 65 \({}^{\circ}\)C, the weight changes of _Fritillaria ussuriensis_ were recorded, and the dry-based moisture content, moisture ratio, and drying rate were calculated. Six thin-layer drying models, including the Page model, Henderson-Pabis model, and Cubic model, were used for fitting. The results indicated that under all three temperature conditions, the Cubic model exhibited a goodness of fit (R\({}^{2}\)) greater than 0.99 with the smallest \(\chi^{2}\) and RMSE values. It can thus most accurately describe the drying kinetic characteristics of _Fritillaria ussuriensis_, providing a theoretical model for the analysis of heat and mass transfer as well as parameter optimization in the drying process. 3. Based on the Box-Behnken test, response surface analysis was conducted with inlet temperature, inlet air velocity, and drying time as influencing factors, and the moisture content of _Fritillaria ussuriensis_ and temperature non-uniformity coefficient as evaluation indicators. The constructed quadratic polynomial regression model was significant (\(p\) < 0.0001), with the lack-of-fit term being not significant (\(p\) > 0.05), and the coefficient of determination (R\({}^{2}\)) exceeding 0.97, indicating high predictive accuracy. The influence degree of the factors was inlet temperature > drying time > inlet air velocity. Considering the actual drying requirements, the optimal process parameters were determined as follows: inlet temperature of 338 K (65 \({}^{\circ}\)C), inlet air velocity of 3 m/s, and drying time of 10 h. Under these parameters, the predicted moisture content was 12.58%, which provides a scientific basis for the process optimization of efficient and uniform drying of _Fritillaria ussuriensis_. 4. A prototype of the drying device was constructed for testing. By comparing changes in the drying chamber temperature, the temperature of _Fritillaria ussuriensis_, and moisture content during the simulated and actual drying processes, it was found that their overall trends were consistent: the actual temperature was 2-3 \({}^{\circ}\)C lower than the simulated value (due to the difference between actual heat dissipation and the ideal simulated environment), and the moisture content decreased from an initial 66.4% to approximately 12% within 12 h, with the error within an acceptable range. The test verified the rationality of the device structure and the reliability of the simulation model. This design provides a new method for drying _Fritillaria ussuriensis_, and its thermal circulation and flow guide structure can be extended to the drying of other traditional Chinese medicinal materials.