A Simulation for Precision Airflow Control using Multi-Fan in a Plant Factory

A new airflow system with multi-fan for precise airflow control and its evaluating method were suggested. A computational fluid dynamics (CFD) simulation was employed to analyze airflow. A cultivation space (1.0×1.0×0.5 m3) was established in the CFD model, and 12 lettuce models with simplified shapes were set in the space. Six small fans were used for generating airflow in the model. In order to verify the accuracy of the CFD model against the actual situation, the same situation as the CFD model were prepared. Lettuce replicas were made of steel meshes with sealing tapes. The accuracy of the CFD model was enough to investigate performances of the airflow control patterns. We assumed that the net photosynthetic rate per plant can be calculated the summation of the net photosynthetic rate calculated with the air current speed and the leaf area in the cell (the minimum unit of the CFD model) on the surface of the lettuce models which were the adjacent cells to the lettuce models. The suggested airflow control pattern could provide more uniform airflow distribution than the conventional airflow pattern and also enhance the net photosynthetic rate more than that in the conventional airflow pattern with the same energy input.