## 3 Results and Discussion
### Investigation of Internal and External Mass Transfer in Different Strategies  
As observed from the drying time (Figure 2), the effective moisture diffusion coefficient varies in different strategies. By plotting ln (MR) versus drying time (s), the value of the effective moisture diffusion coefficient (D\({}_{\text{eff}}\)) is obtained from the Crank model. Moreover, effective moisture diffusion coefficient values by the Dincer model have been calculated according to Equations (6)-(10) based on the dimensionless moisture ratio diagram. The diagram of effective moisture diffusion coefficients by the Crank and Dincer models is shown in Figure 3. The results showed that the increasing air temperature in hot air methods increased the effective moisture diffusion coefficient obtained in both the Crank and Dincer models. This is due to the increase in molecular motion for water molecules and surface suction caused by the rapid evaporation of moisture. Moreover, the increase in radiation intensity causes an increase in the internal temperature and thermal gradient with the outside environment, resulting in the rapid movement of water molecules and increasing the effective moisture diffusion coefficient [43]. Comparing the results of effective moisture diffusion coefficients (D\({}_{\text{eff}}\)) showed that the simultaneously combined strategy (HA-IR) had a higher mass transfer rate than the other strategies. Among all the methods, the highest effective moisture diffusion coefficient of the Crank and Dincer models was obtained in the HA70-IR750 method (1.49 \(\times\) 10\({}^{-9}\) m\({}^{2}\)/s and 1.55 \(\times\) 10\({}^{-8}\) m\({}^{2}\)/s, respectively), and the lowest effective moisture diffusion coefficient was in the IR250+HA40 method (equal to 1.8 \(\times\) 10\({}^{-10}\) m\({}^{2}\)/s and 2.54 \(\times\) 10\({}^{-9}\) m\({}^{2}\)/s, respectively). The highest moisture diffusion coefficient obtained from the Crank model for the combined methods (HA70-IR750) was about 52% higher than the highest moisture diffusion coefficient in the hot air methods (HA70). The highest moisture diffusion coefficient obtained from the Dincer model for the combined methods (HA70-IR750) was about 45.2% higher than the highest moisture diffusion coefficient in the hot air method (HA70). Meanwhile, in research on drying sweet potatoes [25], the IR+HA strategy was reported as the highest effective moisture diffusion coefficient. This difference, as explained, was due to the high level of radiation intensity used in that study. The values of the convective mass transfer coefficient (h\({}_{\text{m}}\)) also decreased or increased following the increase or decrease in the effective moisture diffusion coefficient, and they were affected by the temperature and intensity of the infrared radiation used. According to Figure 4, an increase in temperature and radiation intensity, such as the internal mass transfer coefficient, also increases the external (convective) mass transfer coefficient. The highest convective mass transfer coefficients in the Crank and Dincer models were in the HA70-IR750 method (1.70 \(\times\) 10\  
greater than 1 and for the starting moment, which is a problem that was also mentioned in another research [44]. Therefore, the lag factor coefficients provided in Table 3 are valid only when the MR is less than 1. The drying constant was 1 \(\times\) 10\({}^{-4}\)-8.01 \(\times\) 10\({}^{-4}\) s\({}^{-1}\), the Dincer number was 3.12 \(\times\) 10\({}^{5}\)-2.5 \(\times\) 10\({}^{6}\), and the Biot number was in the range of 0.099-0.216 (Table 3). In research [29] on the convective drying of kiwifruit, the value of the Biot number in the range of 0.172-0.538, the value of the lag factor 1.03-1.077, and the drying constant of 0.712-2.35 \(\times\) 10\({}^{-4}\) were obtained.