# Simulation-Based Analysis of the Effect of New Immersion Freezing Equipment on the Freezing Speed
## 3 Results and Discussion
### Effect of Hopper Rotation Speed on Freezing Time and Freezing Effect of Pork  
To further improve the freezing effect, rotation is used to promote a homogeneous freezing process. This aspect is less covered and few studies can be referred to to explain the results. With the flow rate of the carrier refrigerant constant (v = 1, m/s), five rotational speeds (r = 2, 4, 6, 8, 10) are set to compare the influence of the rotational speed of the rotating hopper on the freezing effect and freezing time of pork. The temperature program in the freezer and the \(x\)-\(y\) plane temperature program of the different rotational speeds are shown in Figure 9.  
Figure 9 shows the temperature distribution in the freezing hopper when the flow rate of the refrigerant is constant and the rotating speed is increasing. Observing the temperature program reveals that the temperature of the refrigerant carrier is kept at the pre-cooling temperature of \(-\)20 \({}^{\circ}\)C. The temperature of pork gradually increases from the outside to the inside, and the maximum temperature in the center reaches \(-\)18 \({}^{\circ}\)C. Observing the temperature program of \(x\)-\(y\) section shows that the temperature gradient of pork is divided into four layers. From outside to inside, the temperature gradually increases. The overall area freezing effect is approximately circular, and the temperature gradient is small. Observing the temperature program and \(x\)-\(y\) cross-section program at five different rotational speeds, indicates that the program at different rotational speeds is approximately the same. However, compared with Figure 5, it can be clearly seen that when the rotating hopper rotates, the freezing effect of pork is significantly more uniform. According to Figures 10 and 11, when the refrigerant flow rate is fixed and the rotating speed is increased from r = 2 rad/s to r = 4 rad/s, the freezing time is reduced by 1290 s from 2310 s to 1020 s, and the freezing efficiency is increased by nearly 55.8%. When the rotating speed is increased from r = 4 rad/s to r = 6 rad/s, the freezing time is reduced from 1020 s to 680 s, which is a change of 340 s, and the freezing efficiency is increased by nearly 33.3%. When the rotating speed is increased from r = 6 rad/s to r = 8 rad/s, the freezing time is reduced from 680 s to 530 s, and the freezing efficiency is increased by nearly 22%. When the rotating speed is increased from r = 8 rad/s to r = 10 rad/s, the freezing time is reduced from 530 s to 480 s, and the freezing efficiency is increased by nearly 9.4%. Figure 8: Refrigeration efficiency change curve with the increase of refrigerant flow rate. Figure 9: _Cont._  
Figure 10: Change curve of pork center temperature and time with the increase of basket speed. Figure 9: Temperature field program and \(x\)-\(y\) section temperature program of the hopper at different speeds. Comparing the temperature programs in Figures 5 and 9, it can be seen that when the rotating hopper is rotating, the temperature distribution of frozen pork is significantly higher than that when the rotating hopper is stationary. However, looking at Figure 9, it can be found that the freezing effect of pork does not change significantly with the gradual acceleration of rotating speed. That is to say, the rotation of the rotating hopper can improve the freezing effect of pork, but the rotation speed does not affect the freezing effect of pork. With the increase of the rotating speed of the loading basket, the time for pork freezing will gradually decrease. It can be seen from Figure 12 that the improvement of refrigeration efficiency will also gradually decrease with the increase of basket speed. This means that it is impossible to shorten the freezing time by continuously increasing the rotating speed. At the same time, the time of the maximum ice crystal band will gradually decrease, and the frozen quality of pork will be improved to a certain extent.