Optimized design of hot air pipe in greenhouse based on CFD technique

The greenhouse environment with Forced-air heating system affected by diameter of hot air pipe (HAP), shape, arrangement, number of exhaust outlet in pipe were simulated by computational fluid dynamics (CFD) technique. The standard k-ε turbulence model, and the Non-gray DO model of radiation model were applied. The numerical solution was made by use of a finite volume discretisation code with the pressure implicit with splitting of operators (PISO) algorithm. Compared with CFD simulation results of 8 cases, the HAP parameters are chosen in the experimental greenhouse, which is a 300mm diameter, circle profile exhaust outlet and 12 exhaust outlets of interlaced arrangement. According to the air pressure distribution in the HAP, the structure is optimized by adjusting the distance of exhaust outlet, which value is used by 1.05. The simulation and experimental results of heating environment in greenhouse show that heating effect of optimized structure is better than the results of other cases.