Optimization of Air Flow Circulation with Branching Perforating Duct and Fan System

Airflow mixing has important role on the environmental control in greenhouse for averaging of temperature, humidity and CO2 concentration. Air mixing performance of branching ducting system was evaluated with computational fluid dynamics (CFD). The branching ducting system for the air heating with the heater, which installing fan, is generally used in small scale greenhouse in Japan. This system has merits on the less distribution and less number of installing fans but has to mind on the pressure loss in duct, which makes air flow distribution in ducts. Numerical model of greenhouse, which has size of 10x5x2 m, installing ducting system was evaluated with CFD simulation model. Simulation conditions were changed by size of holes on duct and fan number and locations. The size of holes limit air flow and the fan locations were influenced to the air flow direction in the greenhouse. System with double fan at opposite corners and large holes for discharge air shows the best performance on mass flow rate and uniformity of flow pattern.