Air distribution optimization of impingement freezer.

The impingement freezer is an emerging equipment to realize the quick freezing of foods. However, there are such problems as low outlet air velocity and high energy consumption in the existing impingement freezers. In this paper, the modifications are mainly focused on the slot outlet forms, fan types and arrangement. To find the outlet form with the highest outlet air velocity, some parameters of the existing slot outlets are optimized. Besides, axial flow fan and centrifugal fan are compared to acquire higher slot outlet air velocity, and the disturbance of fans is investigated by changing the fan rotation direction. As a result, the slot outlet velocity increased when the lower height of slot is reduced. Adding the fillet has little influence on the air velocity. Axial flow fan showed a great energy saving performance compared with the centrifugal fans. The flow field can be improved when two adjacent centrifugal fans rotate reversely rather than in the same direction.